Section 13.26.080 Water Conservation Stage 4. – Severe Water Shortage. (A) Water Conservation Stage 4 is also referred to as a “Severe Water Shortage” and applies during periods when the city will not be able to meet all of the water demands of its customers. Water Conservation Stage 4 may be caused by, but is not limited to, any or all of the following circumstances or events:
(1) a regional or statewide water supply shortage exists and a regional public outreach campaign is being implemented asking or requiring persons to reduce water use; (2) groundwater wells are inoperable or unusable (such as by power outages, mechanical failure, or contamination);
(3) alternative water supplies are limited or unavailable; (4) groundwater levels or groundwater quality is approaching levels which may require augmentation of the groundwater basin or other actions necessary to protect the groundwater basin as prescribed by the California Department of Water Resources, California Department of Public Health, the Regional Water Quality Control Board, Riverside County, or some other regulatory body; and
(5) a major failure of any supply or distribution facility, whether temporary or permanent, occurs in the water distribution system of the State, the Metropolitan Water District of Southern California, the Western Municipal Water District, or city water facilities.
(B) The objective of the measures undertaken in Water Conservation Stage 4 is to reduce water consumption within the city by twenty-one to forty percent as determined and recommended by the General Manager.
(C) Except as otherwise provided in this Section 13.26.080, all water conservation and drought response measures of Water Conservation Stages 1, 2, and 3 shall be in full force and effect during Water Conservation Stage 4. Upon declaration of a Water Conservation Stage 4 by the City Council, implementation by the city and publication of notice, the following water conservation and drought response measures shall apply:
(1) Water customers shall reduce their water consumption by twenty to forty percent from the base year consumption amount for the duration of the Water Conservation Stage 4. Provided, however, the base year consumption amount for subsequent 12 fiscal years shall be determined by the city as appropriate in the event that the city is required to continue the Water Conservation Stage 4 for more than twelve months. (2) Irrigation of landscaping shall be limited to supporting minimal survival of trees and shrubs. Landscaping may be irrigated, including construction meter irrigation, for a maximum of twenty minutes per day only during the following designated watering windows and designated day:
(a) properties with odd number street addresses, parks, and public right of ways may irrigate landscaping only on Saturdays between the hours of 8:00 p.m. and 10:00 a.m.;
(b) properties with even number street addresses may irrigate landscaping and pastures only on Sundays between the hours of 8:00 p.m. and 10:00 a.m.; and (c) irrigating landscaping is prohibited on Mondays, Tuesdays, Wednesdays, Thursdays, and Fridays and outside the designated watering windows set forth in Section 13.26.080(C)(2)(a) and (b).
(3) Notwithstanding the provisions of Section 13.26.080(C) hereof, the use of recycled water to irrigate fruit trees, lawns and ground covers, and ornamental trees and shrubs is permitted on any day and at any time. Recycled water shall not be permitted to run into city streets or the city storm water conveyance system. (4) All outdoor watering and irrigation of lawns and ground covers is prohibited with the exception of plant materials classified and determined by the City Manager to be rare, exceptionally valuable, or essential to the well being of the public at large or rare animals, and for which relief has been otherwise granted pursuant to Section 13.26.150. (5) The washing of automobiles, trucks, trailers, boats, airplanes and other types of mobile equipment is prohibited. Washing is permitted at any time on the immediate premises of a commercial car wash. Commercial car washes shall only use partially reclaimed or recycled water for washing automobiles, trucks, trailers, boats, airplanes and other types of mobile equipment. Further, such washings are exempt from these regulations where the health, safety and welfare of the public is contingent upon frequent vehicle cleanings, such as garbage trucks and vehicles used to transport food and perishables. (6) The filling, refilling, or adding of water to swimming pools, spas, ponds, streams, and artificial lakes is prohibited.
(7) The operation of any ornamental fountain, pond, or similar structure is prohibited except for short periods of time to prevent damage. (8) The use of water for cooling mists is prohibited.
13 (9) The use of water for commercial, manufacturing, or processing purposes shall be reduced in volume by an amount determined by the City Council and/or as recommended by the General Manager.
(10) No new construction meters will be issued. Construction water shall not be used for earth work, road construction purposes, dust control, compaction, or trenching jetting. Construction projects necessary to maintaining the health, safety, and welfare of the public, as determined by the city, are exempt from these regulations. (11) Provided the City Council has declared a water shortage emergency pursuant to California Water Code sections 350 et seq., except as to property for which a building permit has been heretofore issued, no new building permit(s) shall be provided, except in the following circumstances:
(a) for projects necessary to protect the public’s health, safety, and welfare, as determined by the city;
(b) when using recycled water;
(c) when the recipient of the building permit can demonstrate that no net increase in water use will occur; or
(d) where the recipient of the building permit provides a conservation offset. A conservation offset may be effected by paying a fee established by the city in an amount necessary to cover the cost of implementing conservation techniques or acquiring alternative water sources. The fee will be based on the conservation offset required for an equivalent dwelling unit. Such fee shall apply to residential as well as commercial and industrial buildings, and may be adjusted from time to time as determined by the city.
Section 13.26.090 Water Conservation Stage 5. – Critical Water Shortage. (A) Water Conservation Stage 5 is also referred to as a “Critical Water Shortage” and applies during periods when the city will not be able to meet all of the water demands of its customers. Water Conservation Stage 5 may be caused by, but is not limited to, any or all of the following circumstances or events:
(1) a regional or statewide water supply shortage exists and a regional public outreach campaign is being implemented asking or requiring all persons to reduce water use;
(2) groundwater wells are inoperable or unusable (such as by power outages, mechanical failure, or contamination);
14 (3) alternative water supplies are limited or unavailable; (4) groundwater levels or groundwater quality is approaching levels which may require augmentation of the groundwater basin or other actions necessary to protect the groundwater basin as prescribed by the California Department of Water Resources, California Department of Public Health, Regional Water Quality Control Board, Riverside County, or some other regulatory body; and
(5) a major failure of any supply or distribution facility, whether temporary or permanent, occurs in the water distribution system of the State, the Metropolitan Water District of Southern California, the Western Municipal Water District, or city water facilities and the city cannot meet all of the water demands of its customers. (B) The objective of the measures undertaken in Water Conservation Stage 5 is to reduce water consumption by forty percent or more as determined and recommended by the General Manager.
(C) Except as otherwise provided in this Section 13.26.090, all water conservation and drought response measures of Water Conservation Stages 1, 2, 3, and 4 shall be in full force and effect during Water Conservation Stage 5. Upon declaration of a Water Conservation Stage 5 by the City Council, implementation by the city and publication of notice, the following water conservation and drought response measures shall apply:
(1) Water customers shall reduce their water consumption by forty-one percent or more from the base year consumption amount for the duration of Water Conservation Stage 5. Provided, however, the base year consumption amount for subsequent fiscal years shall be determined by the city as appropriate in the event that the city is required to continue the Water Conservation Stage 5 for more than twelve months. (2) All outdoor watering and irrigation of lawns and ground cover, and landscaping is prohibited, with the exception of the use of recycled water to irrigate fruit trees, lawns and ground covers, and ornamental trees and shrubs, which is permitted on any day and at any time. Recycled water shall not be permitted to run into city streets or the city storm water conveyance system.
(3) Provided the City Council has declared a water shortage emergency pursuant to California Water Code sections 350 et seq., the city shall not allow any new connections to the water system during Water Conservation Stage 5.
Section 13.26.100 Mandatory Conservation Phase Implementation. (A) The General Manager, or his or her designee, shall monitor the projected supply and demand for water by its customers on a daily basis during periods of a water shortage or drought and shall recommend to the City Council the extent of the conservation required 15 through the implementation and/or termination of particular water conservation stages to prudently plan and supply water to its customers. Thereafter, the City Council may order the implementation or termination of the appropriate water conservation stage. (B) The declaration of any stage beyond Water Conservation Stage 1 shall be made by the recommendation of the General Manager and resolution of the City Council.
Within ten (10) days of the adoption of the resolution declaring the applicable Water Conservation Stage, the city shall make a public announcement of the applicable Water Conservation Stage, which shall be published a minimum of one (1) time for three (3) consecutive days in a daily newspaper of general circulation. Such declaration and notice shall provide the extent, terms, and conditions respecting the use and consumption of water in accordance with the applicable water conservation stage as provided in this chapter 13.26. Upon such declaration and publication of such notice, due and proper notice shall be deemed to have been given each and every person supplied water within the city. The water conservation stage designated shall become effective immediately upon announcement. (C) The declaration of a water shortage emergency during any water conservation stage shall be made in accordance with California Water Code sections 350 et seq.
Section 13.26.110 Violations and remedies.
(A) It shall be unlawful for any person to willfully violate the provisions of this chapter 13.26. A violation of any of these provisions shall be a misdemeanor subject to imprisonment in the county jail for not more than thirty days or by fine not to exceed $1,000, or by both, as provided in California Water Code section 377. (B) In addition to any remedies or enforcement measures provided by State law or in this chapter 13.26, any violation of this chapter 13.26 is subject to the provisions of chapters 1.08 and 1.09 of the Corona Municipal code.
(C) In addition to any other remedies provided in this Code or available under applicable law, the city can alternatively seek injunctive relief in the Superior Court or take enforcement action, including discontinuing or appropriately limiting water service to any customer, for violations of this chapter 13.26.
Section 13.26.120 Notices and additional enforcement measures. (A) In addition to or in conjunction with the notice of violation provided pursuant to the provisions of chapter 1.08, for a first violation of any provision of this chapter
13.26, within two weeks of the violation:
(1) the city may send an enforcement officer or provide written notice to the property owner, customer, occupant, or responsible person of the property where the violation occurred to advise such person of:
16 (a) the water conservation stage then in effect and the provisions of this chapter 13.26 relating thereto;
(b) water conservation and drought response measures that are required and may be implemented pursuant to this chapter 13.26; (c) possible consequences and actions which may be taken by the city for future violations of this chapter 13.26, including discontinuance of water service; (d) penalties that may be imposed for the specific violation and any future violations of this chapter 13.26; and
(2) if the General Manager or his or her designee deems it to be appropriate, the city may order the installation of a flow-restricting device on the service line for any person who violates any term or provision of this chapter 13.26. (B) In addition to or in conjunction with the notice of violation provided pursuant to the provisions of chapter 1.08, for a second or any subsequent violation of this chapter 13.26, within two weeks of the violation:
(1) the city may send an enforcement officer or provide written notice to the property where the violation occurred to notify the property owner, customer, occupant of the property, or responsible person where the violation occurred to advise such person of:
(a) the water conservation stage then in effect and the provisions of this chapter 13.26 relating thereto;
(b) the water conservation and drought response measures that are required and may be implemented by such person; and (c) possible consequences, which may occur in the event of any future violations of this chapter 13.26;
(2) if the General Manager or his or her designee deems it to be appropriate, the city may order the installation of a flow-restricting device on the service line for any person who violates any term or provision of this chapter 13.26; and (3) if the General Manager or his or her designee deems it to be appropriate, the city may discontinue water service at the location where the violation occurred. (C) The city may, after one written notice of violation, order that a special meter reading or readings be made in order to ascertain whether wasteful or unreasonable use of water is occurring.
17 (D) All moneys collected under this Section 13.26.140 shall be deposited in a special account of the city and shall be made available for enforcement of this chapter 13.26. (E) The city may, at its option, elect to petition the Superior Court to confirm any order establishing administrative penalties and enter judgment in conformity therewith in accordance with the provisions of Sections 1285 to 1287.6, inclusive, of the California Code of Civil Procedure.
Section 13.26.130 Civil actions.
(A) In addition to any other remedies provided in the Code, any violation of this chapter 13.26 may be enforced by civil action brought by the city. (B) In any such action, the city may seek, and the court may grant, as appropriate, any or all of the following remedies:
(1) a temporary and/or permanent injunction;
(2) assessment of the violator for the costs of any investigation, which led to the establishment of the violation, and for the reasonable costs of preparing and bringing legal action under this Section 13.26.130;
(3) any other costs incurred in enforcing the provisions of this chapter
13.26; and
(4) any other action the city deems appropriate to protect the general welfare and the City’s water supplies, and to reduce water consumption in accordance with this chapter 13.26 and the declared policies and laws of the State. (c) Assessments under this subsection shall be paid to the city to be used exclusively for costs associated with implementing or enforcing the water conservation and regulatory provisions of this chapter 13.26.
Section 13.26.140 Recovery of costs.
(A) The General Manager or his or her designee shall serve an invoice for costs upon the person or responsible person who is subject to a notice of violation, a cease and desist order, or an administrative compliance order. An invoice for costs shall be immediately due and payable to the City. If any person or responsible person fails to either pay the invoice for costs or appeal successfully the invoice for costs in accordance with this chapter 13.26, then the City may institute collection proceedings. The invoice for costs may include reasonable attorneys’ fees.
18 (B) The city shall impose any other penalties or regulatory fees, as fixed from time to time by resolution of the City Council, for a violation or enforcement of this chapter
13.26. (C) In addition to the costs which may be recovered pursuant to Section
1.08.022 of the Code, and in order to recover the costs of the water conservation regulatory program set forth in this chapter 13.26, the City Council may, from time to time, fix and impose by resolution fees and charges. The fees and charges may include, but are not limited to, fees and charges for:
(1) any visits of a water conservation specialist, enforcement officer, or other city staff for time incurred for meter reading, follow-up visits, or the installation or removal of a flow-restricting device;
(2) monitoring, inspection, and surveillance procedures pertaining to enforcement of this chapter 13.26;
(3) enforcing compliance with any term or provision of this chapter
13.26;
(4) reinitiating service at a property where service has been discontinued pursuant to this chapter 13.26;
(5) processing any fees necessary to carry out the provisions of this chapter 13.26; and
(6) any other necessary and appropriate fees and charges to recover the cost of providing the city’s water conservation regulatory program.
Section 13.26.150 Relief from compliance.
Consideration of written applications for relief from compliance (“relief”) regarding the regulations and restrictions on water use set forth in this chapter 13.26 may be made by the city.
(A) Written applications for relief shall be accepted, and may be granted or denied, by the approving authority at his or her sole discretion. The application shall be in a form prescribed by the city and shall be accompanied by a non-refundable processing fee in an amount as determined by resolution of the City Council for the purpose of defraying the costs incidental to the review proceedings related thereto.
(B) The grounds for granting or conditionally granting an application for relief are:
19 (1) a customer has reduced water usage to the minimum feasible level but cannot reduce usage by the amount required by then-current mandatory water conservation stage declared pursuant to this chapter due to the number of people in the household or medical necessity, where “reduced water usage to the minimum feasible level” shall mean that the customer has installed xeriscaping or other low-water landscaping (or has ceased watering other types of landscaping), high efficiency water-using appliances, water-efficient toilets, watersaving faucet devices, and low-flow shower heads, and is complying in all other respects with the requirements of this chapter; or
(2) due to unique circumstances other than those described in subsection (1) above, a specific requirement of this chapter 13.26 would result in undue hardship to a person using city water or to property upon which city water is used, that is disproportionate to the impacts to other city water users generally or to similar property or classes of water users; or
(3) failure to grant a relief would adversely affect the health, sanitation, fire protection, or safety of the applicant or the public. (C) The application for a relief shall be accompanied, as appropriate, with photographs, maps, drawings, and other information substantiating the applicant’s request, including a statement of the applicant. Provided, however, the city may request such other additional information as it deems appropriate in order to process and/or review the application for relief.
(D) An application for a relief shall be denied unless the approving authority finds, based on the information provided in the application, supporting documentation, or such other additional information as may be requested, and on water use information for the property as shown by the records of the city, all of the following:
(1) That the relief does not constitute a grant of special privilege inconsistent with the limitations upon other city customers. (2) That because of special circumstances applicable to the property or its use, comprising any of the circumstances set forth in subsection (B) of this section, the strict application of this chapter 13.26 would have a disproportionate impact on (a) the property or use that exceeds customers generally, or (b) the applicant’s health that exceeds customers generally. (3) That the authorization of such relief will not be of substantial detriment to adjacent properties, and will not materially affect the ability of the city to effectuate the purposes of this chapter 13.26 and will not be detrimental to the public interest. (4) That the condition or situation of (a) the subject property or the intended use of the property for which the relief is sought is not common, recurrent, or general in nature, or (b) the applicant’s health or safety is not common, recurrent, or general in nature. 20 (E) The denial or grant of a relief shall be acted upon within fifteen (15) business days of the submittal of the complete application, including any photographs, maps, drawings, and other information substantiating the applicant’s request and the statement of the applicant. The application may be approved, conditionally approved, or denied, subject to subsection (G) of this section. The decision of the approving authority shall be prepared in writing, include terms and conditions, if any, set forth findings in support of the decision, and be promptly sent to the applicant.
(F) The denial of a request for a relief may be appealed in writing to the City Manager. An appeal shall be made in accordance with the following procedures:
(1) The appellant shall complete and submit in writing a form provided by the city for such purpose and shall state in such form the grounds for his or her appeal. The form shall be accompanied by a non-refundable processing fee in an amount as determined by resolution of the City Council for the purpose of defraying the costs incidental to the proceedings. All appeals shall be submitted to the City Clerk within thirty (30) calendar days of the date of the notice of the denial of the request for a relief. (2) The City Manager, or his or her designee, shall review the appeal and any related information provided, and, if necessary, cause an investigation and report to be made concerning the request for a relief. The City Manager, or his or her designee, shall have fifteen (15) calendar days from the submission of the appeal to render a decision on whether to grant or deny the appeal and mail notice thereof to the appellant. The decision shall be prepared in writing, include terms and conditions, if any, and set forth findings in support of the decision. (3) The decision of the City Manager, or his or her designee, may be appealed by the appellant to the City Council. Such appeal must be submitted in writing on the appropriate city form and filed with the City Clerk within fifteen (15) calendar days of the date of decision of the City Manager, or his or her designee. The form shall be accompanied by a non-refundable processing fee in an amount as determined by resolution of the City Council for the purpose of defraying the costs incidental to the proceedings. The City Council shall conduct a hearing on such appeal at its next regularly scheduled City Council meeting; provided, however, the City Council shall have received the notice of appeal at least fifteen (15) calendar days prior to such meeting. If the appeal is not submitted within at least fifteen (15) calendar days prior to a regularly scheduled City Council meeting, then the hearing shall be held at the following regularly scheduled City Council meeting. A notice of the hearing shall be mailed to the appellant at least ten (10) calendar days before the date fixed for the hearing. The City Council shall review the appeal de novo. The determination of the City Council shall be conclusive. Notice of the determination by the City Council shall be mailed to the appellant within ten (10) calendar days of such determination, indicate whether the appeal has been granted in whole or in part, set forth the terms and conditions of the relief, if any, granted to the appellant, and set forth findings in support of the decision. If the appeal is denied in its entirety, the appellant shall comply with all terms and conditions of this chapter 13.26 and the applicable water conservation stage then in effect.
21 (4) Until the conclusion of the appeal process, all provisions and decisions under appeal shall remain in full force and effect until the conclusion of the appeal process.
(G) Any grant of a request for relief shall be conditioned upon the continued existence of the facts and circumstances which formed the grounds for granting relief, as provided in this section. The approving authority may revoke any grant of relief if such facts and circumstances are determined no longer to exist.
Section 13.26.160 Water Conservation Programs.
(A) Subject to available funds, the City Manager, or his or her designee, is authorized to develop, promote, and administer water conservation programs to encourage and assist persons in conserving water. The water conservation programs may include, but are not limited to, the following:
(1) installing, or providing rebate programs for the installation of, water saving devices and irrigation systems in the landscaped areas of residential, commercial, industrial, and public property and public rights-of-way; (2) replacing landscaping and turf with drought tolerant plant material and water efficient landscaping;
(3) developing educational programs to promote water conservation; and
(4) converting, where financially and technically feasible, potable water distribution systems to recycled water distribution systems for landscaped areas of residential, commercial, industrial, and public property and public rights-of way. (B) The City Manager shall prepare and implement policies and procedures governing any water conservation program established pursuant to this Section 13.26.160. (C) The City Manager is authorized to enter into agreements relating to such water conservation programs, provided such agreements are approved as to form by the City Attorney.
(D) The expenditure of funds for any water conservation program shall be subject to the provisions of Chapter 3.08, as applicable, and any other provisions of the Municipal Code restricting the expenditure of city funds.
Section 13.26.170 Conflicting Provisions.
If provisions of this chapter 13.26 are in conflict with each other, other provisions of the Code, any other resolution or ordinance of the city, or any State law or regulation, the more restrictive provisions shall apply.
Appendices
City of Corona
2025 Urban Water Management Plan
Appendix O – Water Shortage Contingency Plan
Appendices
City of Corona
2025 Urban Water Management Plan
Appendix P – Local Hazard Mitigation Plan
2023 ‐ 2027
Local Hazard Mitigation Plan
City of Corona, CA
Corona Fire Department
Emergency Services Division
CITY OF CORONA 1
LOCAL HAZARD MITIGATION PLAN
FEB 2023
Contact Information
City of Corona
Name: Lee Shin
Title: Emergency Services Manager
Address: 735 Public Safety Way
City, State and Zip: Corona, CA 92880
Direct Contact: 951-496-1299
Email: [email protected]
2 LOCAL HAZARD MITIGATION PLAN
2022 – 2027 CITY OF CORONA
PLAN ADOPTION AND RESOLUTION
The City of Corona will submit plans to the Riverside County Emergency Management Department (EMD) who will then forward the plans to the California Governor’s Office of Emergency Services (Cal OES) for review prior to being submitted to the Federal Emergency Management Agency (FEMA). In addition, we will wait to receive an “Approval Pending Adoption” letter from FEMA before taking the plan to our local governing bodies for adoption. Upon approval, the City of Corona will insert the signed resolution into this publication.
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EXECUTIVE SUMMARY
The purpose of this Local Hazard Mitigation Plan (LHMP) is to identify the City’s hazards, review and assess past disaster occurrences, estimate the probability of future occurrences, and set goals to mitigate potential risks to reduce or eliminate longterm risks to preserve and protect life, property, and the environment from both natural and man-made hazards.
The plan was prepared pursuant to the requirements of the Disaster Mitigation Act of 2000 to achieve eligibility and potentially secure mitigation funding through FEMA’s Flood Mitigation Assistance, Pre-Disaster Mitigation, and Hazard Mitigation Grant Programs.
Riverside County's continual efforts to maintain a disaster-mitigation strategy is ongoing. Our goal as the City of Corona is to develop and maintain an all-inclusive plan to include all jurisdictions, special districts, businesses, and community organizations to promote consistency, continuity and unification throughout the county and city.
The County’s planning process followed a methodology presented by FEMA and Cal OES which included conducting meetings with the Operational Area Planning Committee (OAPC) coordinated by Riverside County EMD comprised of participating Federal, State, Local, Tribal, and Territorial (SLTT)governmental bodies and local jurisdictions agencies, special districts, school districts, non-profit communities, universities, businesses, and public.
The plan identifies vulnerabilities, provides recommendations for prioritized mitigation actions, evaluates resources, identifies mitigation shortcomings, provides future mitigation planning, and maintenance of the existing plan.
The plan will be implemented upon FEMA approval.
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5 LOCAL HAZARD MITIGATION PLAN
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TABLE OF CONTENTS
Table of Content
Contact Information ....................................................................................................................... 1 PLAN ADOPTION AND RESOLUTION ........................................................................................ 2 EXECUTIVE SUMMARY .............................................................................................................. 3 TABLE OF CONTENTS ................................................................................................................ 5 CHAPTER 1- COMMUNITY PROFILE ......................................................................................... 6
1.1 CITY OF CORONA MAP ............................................................................................ 6
1.2 GEOGRAPHY AND CLIMATE DESCRIPTION .......................................................... 6
1.3 BRIEF HISTORY OF CORONA .................................................................................. 8
1.4 DESCRIPTION OF CORONA’S ECONOMY ............................................................ 10 Figure 1.4.1 – City of Corona Workforce ............................................................................. 13
1.5 POPULATION AND HOUSING ............................................................................... 14
1. 6 TRENDS AND LAND USE ....................................................................................... 18 CHAPTER 2 - PLANNING PROCESS ........................................................................................ 15
2.1 LOCAL PLANNING PROCESS ................................................................................ 15
2.2 PARTICIPATION IN REGIONAL PLANNING PROCESS ........................................ 15
2.3 DATES AVAILABLE FOR PUBLIC COMMENT ....................................................... 16
2.4 PLANS ADOPTED BY RESOLUTION ...................................................................... 16 CHAPTER 3 – MITIGATION ACTIONS AND UPDATES ........................................................... 17
3.1 UPDATES FROM 2017 PLAN .................................................................................. 17
3.2 LIST OF COUNTY AND CITY HAZARDS ................................................................ 17
3.3 NEW HAZARDS OR CHANGES FROM 2017 LHMP ............................................... 20
3.4 UNIQUE HAZARDS OF THE COUNTY AND CITY .................................................. 21
3.5 MITIGATION PROJECT UPDATES ......................................................................... 25 CHAPTER 4.0 – HAZARD IDENTIFICATION AND RISK ASSESSMENT ................................. 28
4.1 CRITICAL FACILITIES AND INFRASTRUCTURE ................................................... 28
4.2 ESTIMATING POTENTIAL LOSS ............................................................................ 30
4.3 TABLE OF REPLACEMENT VALUES ..................................................................... 30
4.4 IDENTIFICATION OF RISKS AND VULNERABILITIES ........................................... 30 SECTION 5.0 – COMMUNITY RATING SYSTEM ..................................................................... 49
5.1 REPETITIVE LOSS PROPERTIES .......................................................................... 49
5.2 NATIONAL FLOOD INSURANCE PROPERTIES .................................................... 49 SECTION 6.0 - CAPABILITIES ASSESSMENT ......................................................................... 51
6.1 REGULATORY MITIGATION CAPABILITIES .......................................................... 51
6.2 ADMINISTRATIVE ANDTECHNICAL MITIGATION CAPABILITIES ........................ 53
6.3 FISCAL MITIGATION CAPABILITIES ...................................................................... 54
6.4 MITIGATION OUTREACH AND PARTNERSHIPS .................................................. 54
6.5 FUNDING OPPORTUNITIES ................................................................................... 55 SECTION 7.0 - MITIGATION STRATEGIES .............................................................................. 56
7.1 GOALS AND OBJECTIVES ...................................................................................... 56
7.2 MITIGATION ACTIONS ............................................................................................ 57
7.3 ON-GOING MITIGATION STRATEGY PROGRAMS ............................................... 62
7.4 FUTURE MITIGATION STRATEGIES ...................................................................... 64 SECTION 8.0 – PLAN IMPLEMENTATION AND MAINTENANCE PROCESS ...................................... 65 SECTION 9.0 – INCORPORATION INTO EXISTING PLANNING MECHANISMS .................... 67 SECTION 10.0 - CONTINUED PUBLIC INVOLVEMENT ........................................................... 67 APPENDIX A – PUBLIC NOTICES AND MAPS ................................................................................. 69 .................................................................................................................................................... 82 6 LOCAL HAZARD MITIGATION PLAN
2022 – 2027 CITY OF CORONA
APPENDIX B – INVENTORY WORKSHEETS ........................................................................... 88 APPENDIX C – PLAN REVIEW TOOL/CROSSWALK ...................................................................... 109 CHAPTER 1- COMMUNITY PROFILE
1.1 CITY OF CORONA MAP
1.2 GEOGRAPHY AND CLIMATE DESCRIPTION
The City of Corona is located approximately 45 miles southeast of Los Angeles in western Riverside County. It is in a valley, framed by forests and mountains, and the Prado Basin. Original settlements in the area focused on development within and adjacent to Grand Boulevard. As the City grew, the geographic limitations imposed by the Cleveland National Forest to the south and the Prado Basin to the northeast created natural barriers that confined the City. Corona is bordered by the City of Norco to the north, the City of Riverside to the east, and other Riverside County cities to the west and south.
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2022 – 2027 CITY OF CORONA
The City limits encompass 39.2 square miles and the population is approximately 159,743 (according to the United States Census Bureau’s assessment in July 2021).
Corona, a city whose heritage spans more than a century, has emerged as an ethnically diverse community, where a significant percentage of the population is made up of young and well-educated families. The City’s community boasts many amenities that provide a first-rate quality of life for its residents. It also has more than 394 acres of parks that include sports fields, basketball courts, playgrounds, tennis courts, two skate parks, and an outdoor pool.
Two major freeways and one railroad transect Corona. The Riverside Freeway (SR91) runs east and west directly north of the City’s center, Interstate 15 (I-15) runs north and south near the eastern edge of the City, and the railroad parallels SR-91. These corridors act as major transportation routes to the economic center of Orange County from the Inland Empire.
Two geographical areas are within the boundaries of the City of Corona General Plan Planning Area: lands within the City’s corporate limits and lands within its Sphere of Influence (SOI). The City currently includes 39.2 square miles, plus 34.3 square miles in Riverside County designated as being within the SOI.
The SOI was defined by the City, the Southern California Association of Governments (SCAG), and the Riverside County Local Agency Formation Commission (LAFCO). It represents the areas likely to be served by and potentially annexed to the City. The SOI includes three geographically distinct areas including the West, East, and South Spheres. The West Sphere encompasses three geographic areas: the Prado Basin, Coronita, and the Foothill Area. The East Sphere includes the areas of Home Gardens, Eagle Valley East, and El Cerrito. Additionally, the Temescal Canyon makes up the South Sphere.
The City of Corona Planning Area is within the South Coast Air Basin of California (SCAB). The Air Basin is a 6,600-square mile area encompassing the non-desert portions of Riverside, Los Angeles, and San Bernardino Counties as well as all of Orange County. Bounded by the Pacific Ocean to the west and the San Gabriel, San Bernardino, and San Jacinto Mountains to the north and east, the South Coast Air Basin is an area of high air pollution potential.
The climate of the SCAB is dominated by the strength and position of the semipermanent high-pressure center over the Pacific Ocean near Hawaii. 8 LOCAL HAZARD MITIGATION PLAN
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It creates the climate conditions typical of Southern California, (i.e., relatively cool summers, mild winters, infrequent rainfall, cool daytime sea breezes, comfortable humidity, and ample sunshine). Periods of extremely hot weather, winter storms, or Santa Ana wind conditions interrupt this pattern. Unfortunately, the same atmospheric processes that create the desirable living climate can combine to restrict the ability of the atmosphere to disperse the air pollution generated by the region’s population.
The location of the Planning Area (east of the Chino Hills and Santa Ana Mountains) insulates it from the moderating effect of the ocean. Average summertime high temperatures range between about 85 to 92 degrees Fahrenheit from June through September, and average wintertime low temperatures are generally near 40 degrees in the months of December and January. Rainfall is highly variable and confined almost exclusively to the winter months. Rainfall in Corona averages about 12.6 inches annually. Temperatures and precipitation in Corona tend to vary more dramatically than other coastal areas of the basin.
Predominating winds travel from the ocean, across the urbanized coastal areas of Orange and Los Angeles Counties, to Corona through the Santa Ana River Canyon.
The canyon acts as a funnel for air masses moving across the basin. Daytime winds are typically channeled through the canyon to create steady, abnormally high (greater than 12 mph) wind velocities from the west. Typical nighttime conditions reverse, and light winds (less than 1 mph) drift back towards the ocean. Exceptions to this pattern occurs when a high-pressure center forms over the western United States and creates the strong, hot, dry, gusty Santa Ana winds, which move through Corona from the eastern deserts into the canyon.
1.3 BRIEF HISTORY OF CORONA
Corona’s historic resources are those physical elements, both structural and natural, which define the City’s past. They help give the City its unique identity, charm, and orientation. These resources, when well preserved and maintained, provide the community with a sense of permanence, which fosters civic pride and stewardship among its residents and businesses. Information describing the historic and cultural resources were derived from the 2000 Riverside County Integrated Project (RCIP).
Corona’s history has evolved on behalf of Native American inhabitation, missionary influence, agricultural development, and eventual rapid urbanization. The City’s growth and development is typical of many other areas in Southern California. 9 LOCAL HAZARD MITIGATION PLAN
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In the early 1700s, prior to the arrival of the Spanish, the Gabrieleno and Luiseno Native American Tribes occupied the Corona area. These indigenous peoples used the hot waters in the Temescal Canyon for bathing and religious ceremonies.
Current residents and visitors still enjoy the rejuvenating mud baths and hot springs at the Glen Ivy Springs Resort. Luiseno religious ceremonies were strictly followed and remnants of some of their artistic pictographs and petroglyphs can still be found on rocks in undeveloped areas.
In the early 1800s, the agricultural and cattle ranching base developed, and portions of Corona became part of the Mexican land grant program (i.e., Rancho La Sierra Yorba, Rancho Jurupa, Rancho El Rincon, and Rancho El Sobrante de San Jacinto).
With the Treaty of Guadalupe Hidalgo signed in 1846, Mexico ceded the Corona area as part of California to the United States. The Yorba, Serrano, Sepulveda, Cot, and Botiller families’ ranched sheep and cattle on the original ranchos in the area.
Remnants of the Serrano tanning vats are still found on Old Temescal Canyon Road.
In 1849, the California gold rush brought prospectors, settlers, and new developments to Southern California.
In 1886, developer Robert Taylor persuaded his partners: Rimpau, Joy, Garretson, and Merrill to form the South Riverside Land and Water Company. Together they raised approximately $110,000 to purchase approximately 12,000 acres of agricultural land. Taylor realized the importance of water for the soon to be developed community and additional funds were used to ensure that sufficient water rights were obtained.
Taylor hired Anaheim engineer H. C. Kellogg to design a circular Grand Boulevard three miles round. Early residents used to parade their fancy buggies on this circular street which enclosed the main functions of the community: schools, churches, residences, and stores. To the north along the railroad tracks were the manufacturing plants and packing houses. The southern end of town featured the citrus industry, and the mining companies were established just outside the City’s southeastern and eastern city limits.
The developers initially named their development South Riverside after the successful citrus community of Riverside located nearby. Almost all the new settlers planted orange and lemon trees in hopes of gaining future profits. New groves continued to spring up and by 1912 there were 5,000 acres of established orange and lemon groves. By 1913, Corona shipped more fruit than any other town in Southern California. In 1961, citrus was still considered the backbone of Corona’s economy and the largest source of revenue. In that year, citrus covered 7,500 acres. The labor force fluctuated between 400 and 1,800 workers at the peak of the harvest. An additional 500 people worked at the Exchange Lemon Products Plant. By 1982, Corona’s 10 LOCAL HAZARD MITIGATION PLAN
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agricultural industry faced a bleak future as production costs made the economics of farming financially unsuccessful. Plans then began to change to replace the groves with approximately 12,500 dwelling units.
On July 13, 1896, residents voted to incorporate and change the name of the community to Corona, which is Spanish for crown, in honor of the City’s circular Grand Boulevard.
By 1900, the population had reached 1,434 people.
On September 9th, 1913, in observance of California’s Admission’s Day, Corona residents celebrated with an international automobile race on the Boulevard. The event attracted auto racing greats such as Ralph DePalma, Barney Oldfield, Terrible Teddy Tetzlaff, and Earl Cooper. More than 100,000 people came to the town to watch Cooper win the race and a prize of $8,250. It was so successful that races were held again in 1914 and 1916. The demise of the Corona Road races was due not only to tragic deaths, which occurred in 1916, but also because of the cost and local effort needed to continually stage such an extravagant event.
1.4 DESCRIPTION OF CORONA’S ECONOMY
Corona continues to maintain its position as the premier location for businesses looking to relocate and expand. Corona’s geographic position attracts a highly educated labor force. Vacancy rates in industrial, commercial, and office properties all declined in 2022, with many companies returning to in-person work. Industrial vacancy rates dropped even lower to 1.0%, retail vacancies dropped to 5.2%, and office vacancy rates steadily declined to 7.5%.
Taxable sales in Corona totaled just over $900 million in the fourth quarter of 2020, down 6.3% from the previous year. This is a more modest decline relative to Los Angeles County (-8.9%) and Orange County (-7.4%), but it contrasts with the growth in Riverside County (3.9%) and San Bernardino County (6.2%). From the first quarter of 2020 to first quarter of 2021, the pandemic led to a surge in spending in some categories. E-commerce surged during the pandemic, with spending up 43.4%.
Demographically, Corona benefits from a young median age, higher education levels, higher median incomes, and higher home values compared to Riverside County and other areas in California. As a thriving inland community, Corona is home to young families comprised of 48,905 households averaging 3.25 persons each, with a median age of 38.3. Annual median household income is $92,606 and 76% of the population age 25 and up possess a high school diploma or higher according to U.S. Census.
Median home prices continue to improve with median values in excess of $620,600. 11 LOCAL HAZARD MITIGATION PLAN
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New industrial development, business expansions, and relocations to Corona have helped to stabilize Corona’s job market, despite economic impacts related to the global pandemic. Job growth in Corona reported a 10% increase with employment numbers increasing to 86,700 in the first quarter of 2022. Major contributors to local economic growth are the construction, health care, and finance industries, in addition to the fast-growing professional, management, and technology sectors in previous years. Job growth will be continuing to be fueled by the 1.8 million square feet of industrial development recently completed or under construction, and the recent completion of 147,000 square feet of Class A offices. The strong local job market keeps the unemployment rate in Corona at 3%, which is approximately 1% below the Riverside County average as of Fiscal Year 2021.
Fiscal Year 2022 continued to see an expanding housing market with increased median home prices and average rents for multi-family communities. New singlefamily housing developments include Sierra Bella, a new family community consisting of 237 single family homes and Bedford South Corona, which will add more than 1,500 single family units once complete along with Corona’s newest retail development, Bedford Marketplace. Both developments are under construction, with some homes complete and occupied by new homeowners. Several proposed condominium developments are in various stages of plan check or construction including 109 attached units on the east side of Temescal Canyon Road and Dos Lagos Drive.
With limited opportunities for large-scale new development, Corona continues looking for opportunities to redevelop and expand currently underutilized properties.
Through its ongoing commitment to stimulate the local economy and expand its labor force, the City of Corona will continue to be the premier inland Southern California city to live, work, and play.
Nationwide, the economy has continued to show strong recovery from early COVID19 pandemic shutdowns. The national unemployment rate was 3.6% at the end of Fiscal Year 2022 and increased to 3.7% in the first quarter of Fiscal Year 2022.
However, national economic performance does not directly translate to improved or hindered financial condition for local governments, nor opportunities to fund more services. As an example, a rise in home prices does not directly correlate to the City collecting more in property taxes. With Proposition 13, property tax is capped at 1%, and the property’s taxable value cannot increase more than 2% per year. At the same time, the increase in fixed cost for operating City government has outpaced its revenue growth.
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Figure 1.4.1 – City of Corona Workforce
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1.5 POPULATION AND HOUSING
In a little over a century, the City has evolved from a small town of 1,434 people with deep agricultural roots to a dynamic, diverse community of more than 167,759 people.
At the turn of the millennium, Corona’s growth had been among the highest in the United States. It’s vast agricultural areas at the base of the Santa Ana Mountains, La Sierra Hills, and Chino Hills that is centered on a single place of business and civic identity, has evolved to a suburban community of multiple neighborhoods and centers of commerce and employment. Based on estimates from the California Department of Finance, the City’s housing units has increased to 50,287 in 2023 from 48,064 in 2014 from, an increase of approximately 2,223 units.
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Figure 1.5.1 – City of Corona Demographics
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1. 6 TRENDS AND LAND USE
Corona’s residential market continues to boom. Included in future planned construction are three new housing developments that will be adjacent to high fire hazard severity zones. It is mandated that new development in or adjacent to these zones follow the 2016 California Building Code Chapter 7A and Chapter 49 of the 2016 California Fire Code. It is also mandated by the Corona Fire Department that a separate fuel modification plan be submitted for review and approval.
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Figure 1.6.1: Responsibilities within City of Corona
JURISDICTION: CITY OF CORONA DOES YOUR AGENCY HAVE RESPONSIBILITY FOR LAND USE AND/OR DEVELOPMENT ISSUES WITHIN YOUR JURISDICTIONAL BOUNDARIES?
2012 DATA 2017 DATA 2023
Current Population in Jurisdiction or Served 153,649 167,759 Projected Population in Jurisdiction or Served - in 2022 175,000
Current Sq. Miles in Jurisdiction or Served 39.2 39.2 Projected Sq. Miles in Jurisdiction or Served - in 2022 39.2 Does Your Jurisdiction have any ordinances or regulations dealing with disaster mitigation, disaster preparation, or disaster response? Yes Yes
If yes, please list ordinance or regulation number. Ordinance No. 2429, 1973, 2077 Corona Municipal Code Chapters 2.52, 3.36, 4.04.80, 7a, 15.12.270 Section 705 What is the number one land issue your agency will face in the next five years Economy and Infill/compact development
Approximate Number of Homes/Apts/etc. 47,182 48,930 Projected Number of Homes/Apts/etc.- in 2022 50,500
Approximate Total Residential Value $16.3 billion $17.0 billion Projected Residential Total Value - in 2022 $19.0 billion Approximate Number of Commercial Businesses 5,205 9,000 Projected Number of Commercial Businesses - in 2022 9,500 Approximate Percentage of Homes/Apts/etc. in flood hazard zones
0.7% 0.7% Approximate Percentage of Homes/Apts/etc. in flood hazard zones - in 2022
0.7%
Approximate Percentage of Homes/Apts/etc. in earthquake hazard zones
3.5% 3.5% Approximate Percentage of Homes/Apts/etc. in
earthquake hazard zones - in 2022
3.5%
Approximate Percentage of Homes/Apts/etc. in wildland fire hazard zones
6.55% 6.55% Approximate Percentage of Homes/Apts/etc. in wildland fire hazard zones - in 2022
6.55%
Approximate Percentage of Commercial Businesses in flood hazard zones
0.003% 0.7% Approximate Percentage of Commercial Businesses in flood hazard zones - in 2022
0.7%
Approximate Percentage of Commercial Businesses in earthquake hazard zones
1.9% 0.3% Approximate Percentage of Commercial Businesses in earthquake hazard zones - in 2022
0.3%
Approximate Percentage of Commercial Businesses in wildland fire hazard zones
4.5% 0 Approximate Percentage of Commercial Businesses in wildland fire hazard zones - in 2022
0 Number of Critical Facilities in your Jurisdiction that are in flood hazard zones 0 0 Projected Number of Critical Facilities in your Jurisdiction that are in flood hazard zones - in 2022
0 Number of Critical Facilities in your Jurisdiction that are in earthquake hazard zones 2 2 Number of Critical Facilities in your Jurisdiction that are in earthquake hazard zones - in 2022
2 Number of Critical Facilities in your Jurisdiction that are in wildland fire hazard zones. 7 7 Number of Critical Facilities in your Jurisdiction that are in wildland fire hazard zones - in 2022
7 Does your jurisdiction plan on participating in the County's on-going plan maintenance program every two years as described in Part I of the plan? Yes Yes If not, how will your jurisdiction do plan maintenance? N/A Will a copy of this plan be available for the various planning groups within your jurisdiction for use in future planning and budgeting purposes? Yes
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CHAPTER 2 - PLANNING PROCESS
2.1 LOCAL PLANNING PROCESS
Multiple city departments contributed to the update of the 2023 Local Hazard Mitigation Plan. Personnel involved included senior management and staff from the Fire Department, Police Department, Community Development, Public Works, Administrative Services, Department of Water and Power, Management Services, Maintenance Services, Library and Recreation, Information Technology, City Clerk, Legal, and Risk Management. The group also includes civil engineers, planners, building officials, city clerks, public information officers (PIO), Geographic Information System (GIS) administrator, accountants, managers, emergency managers, analysts, and fire and police officials. Outreach to key stakeholders was done through email, phone calls and in person meetings.
The group assisted in the development of mitigation strategies and projects based on the risk and hazard ranking assessment conducted by members of Fire, Police, Public Works Departments as well as the Department of Water and Power. They identified completion of past projects and provided updated City data and statistics. For meetings and correspondence records, please reference local planning efforts within Appendix A.
2.2 PARTICIPATION IN REGIONAL PLANNING PROCESS
The City of Corona committed to participating in the update of the 2022 Riverside County Multi-Jurisdictional Hazard Mitigation Plan (MJHMP). An agency multijurisdiction participation form was completed and submitted to Riverside County Emergency Management Department as official notice of participation.
Emergency Management staff attended multiple OA Planning Committee meetings over the course of the planning year where LHMP updates, requirements, and coordinating efforts were conducted.
Neighboring communities were also invited to participate in the update of the LHMP during these quarterly OAPC meetings. Several of Corona’s neighboring communities were in the process of updating their respective LHMPs which allowed the city to cross reference mitigation hazards and risks while also identifying potential mitigation projects that may lead to future collaborate efforts.
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Corona Emergency Management staff attended multiple LHMP workshops hosted by EMD that provided additional information, review, guidance, and assistance throughout the plan’s updating process. These workshops consisted of representatives from various disciplines such as law, fire, hospitals, and schools lending to a well-rounded planning process. These entities were invited by EMD to participate in these workshops via OA emailing distribution lists and calendar invites. In addition to these group settings, the Corona Emergency Services Manager had multiple one on one meetings and email correspondence with EMD planning staff. For meetings and correspondence records, please reference OA planning efforts within Appendix A.
2.3 DATES AVAILABLE FOR PUBLIC COMMENT
In an effort to involve the residents of Corona in the update process, and to better understand their concerns and opinions regarding hazards threatening their community and the City as a whole, a survey was developed and the 2023 plan was provided for review. To reach many community members, the plan and survey were posted on the City’s website as well as on social media. The post on the Corona Fire Department Facebook page, which contained the survey and plan, reached over 3,527 individuals.
In addition to these efforts, LHMP information and input was given and received at multiple community meetings.
No new hazards outside of the current contents of the 2023 LHMP were identified. For public notice documentation, please see Appendix A.
2.4 PLANS ADOPTED BY RESOLUTION
Upon approval by FEMA, the LHMP will be presented to the City Council in a public meeting for adoption via an Official Resolution.
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CHAPTER 3 – MITIGATION ACTIONS AND UPDATES
3.1 UPDATES FROM 2017 PLAN
The 2023 LHMP update was a complete review and rewrite of many of the sections to align with the four-step planning process and incorporate updated information across the plan. Many of the 2017 LHMP sections were renamed or adjusted in their order within the 2023 update.
Although no new hazards have been identified, the occurrence or severity of some of these hazards has increased, making them a greater mitigation priority than in previous years. Please see section 3.3 for further information on updates since the publication of the 2017 LHMP.
3.2 LIST OF COUNTY AND CITY HAZARDS
The City of Corona is committed to providing protection to residents and businesses from natural and man-made hazards. The City is also committed to coping with and rebuilding from disasters and emergencies in a manner that is efficient, safe, and provides for a quick return to the quality of daily life in Corona. To accomplish this, it is imperative that the City is aware of the hazards it is susceptible to in order to prepare, respond, recover, and mitigate the applicable hazards.
The County of Riverside identified, evaluated, and ranked 23 natural and man-made public safety risks that could have an impact on the health, safety, and social well-being of communities located within it. The rankings were based on severity of damage and probability of occurrence for each risk. The City of Corona then ranked the same 23 hazards and included the top 10 risks in the City’s annex to the Riverside County MJHMP. Identifying the risks posed by these hazards and developing strategies to reduce the impact of these hazards can assist in protecting and preserving life, property, and the environment.
All 23 hazards are not individually addressed in the City of Corona’s annex. For those hazards not expanded upon, the City feels that the County Plan provides adequate information to address the hazard as it relates to the City. Below are two tables, one identifies the 23 identified hazards with their probability and severity rates and the second lists the County and City final ranking of the hazards.
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Figure 3.2.1 – County and City Hazard Rankings
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Figure 3.2.2 – Hazard Probability and Severity Rates
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3.3 NEW HAZARDS OR CHANGES FROM 2017 LHMP
Although no new hazards have been identified from the approval of the 2017 LHMP the occurrence or severity of some of these hazards has increased, making them a greater mitigation priority than in previous years. Examples of these heightened risks include drought, climate change, occurrences of pandemic outbreaks and their associated threats, and the threat and occurrences of both domestic and international terrorist acts.
1. Drought – Drought is a period of unusually constant dry weather that persists long enough to cause deficiencies in the water supply (surface or underground).
Droughts are slow-onset hazards, but over time, they can severely affect crops, municipal water supplies, recreation resources, and wildlife. If drought conditions extend over several years, the direct and indirect economic impacts can be significant. High temperatures, high winds, and low humidity can worsen drought conditions and make areas more susceptible to wildfires. In addition, human actions and demands for water resources can accelerate drought-related impacts.
2. Climate change – Climate change may well be the preeminent challenge of our time and it is already having a significant and measurable impact on California’s environment. These impacts include decreasing spring snowmelt runoff, rising sea levels, shrinking glaciers, increasing wildfires, warming lakes and oceans, and the gradual migration of many plants and animals in higher elevations.
Weather patterns are becoming more variable, causing more severe winter and spring flooding and longer drier droughts. Climate change has already impacted California’s water resources. In the future, warmer temperatures, different patterns of precipitation and runoff, and rising sea levels will profoundly affect the ability to manage water supplies and other natural resources.
3. Pandemic – An influenza pandemic is a global outbreak of a new Influenza A virus. A Novel Influenza A virus is one that has caused human infection but is different from current seasonal human influenza A viruses spreading among people. Novel Influenza A viruses can be viruses that originate in animals that gain the ability to infect humans or human viruses that change significantly to be different from current human seasonal Influenza A viruses. Some Novel Influenza A viruses are believed to pose a greater pandemic threat than others and are more concerning to public health officials because they have caused serious human illness, death, and have been able to spread in a limited manner from person-to-person.
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4. Novel Influenza A viruses are of extra concern because of the potential impact they could have on public health if they gained the ability to spread from personto-person easily, which could potentially trigger a pandemic. There are various subtypes of Avian Influenza A viruses to include H5, H7, H9, H1N1v, H3N2v, and H1N2v, which are currently most concerning to public health officials.
5. The COVID-19 pandemic, also known as the coronavirus pandemic, is an ongoing global pandemic of coronavirus disease 2019 caused by severe acute respiratory syndrome. As of January 2023, the COVID-19 pandemic had caused more than 668 million deaths and 6.73 million confirmed deaths, making it one of the deadliest in history.
6. Terrorism – As defined by the FBI, terrorism is "the unlawful use or threatened use of violence committed against persons or property to intimidate or coerce a government, the civilian population, or any segment thereof, in furtherance of political or social objectives.” The tactics of terrorism are diverse. The fear of such attacks within the target population is just as important as the actual attacks, making the threat of violence as effective as actual violence. Terrorist tactics tend to favor attacks that avoid effective countermeasures and exploit vulnerabilities.
As such, terrorists have the potential to utilize many different types of tactics both conventional and unconventional. Some of these tactics include shootings, kidnappings, bombings, suicide attacks, bioterrorism, nuclear terrorism, and cyberterrorism. From 2010 to 2023 there have been roughly 40 confirmed domestic terrorist incidents.
3.4 UNIQUE HAZARDS OF THE COUNTY AND CITY
The City of Corona faces a diverse array of potential natural and human caused hazards. As with most cities in the Inland Empire, one of the primary concerns is the impact of a large earthquake in the region. Flood risks are also a real concern with several creeks, washes, channels, and flood zones contained in the planning area of Corona. In addition, the City is nearly surrounded by hills and mountains with the potential and the history of large wildland fires. The shared boundary between the City and the Cleveland National Forest is about 12 miles in length.
The City’s extensive transportation network which includes state highways, public transit, rail lines, and a municipal airport provide additional associated incident risks that may cause severe injuries and/or deaths. They could also cause burns and/or illness due to exposure to fires and/or potential hazardous materials on board. Two major freeways and one railroad transect Corona.
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The Riverside Freeway (SR-91) runs east/west directly north of the City’s center, Interstate 15 (I-15) runs north/south near the eastern edge of the City, and the railroad parallels the SR-91. These corridors are major transportation routes to the economic center of Orange County from the Inland Empire. The Corona Municipal Airport is home to 300-350 general aviation aircraft and is strictly a recreational airport with no commercial flights.
Although small, the airport is extremely active, with approximately 35,000 annual operations. The City's transportation network of roads, freeways, rail lines and airport has been a priority in the City’s planning and mitigation efforts.
Since the original 2005 version of the LHMP was submitted, the City of Corona has experienced 7 federally declared disasters for wildland fires and floods, and a state disaster declaration for high winds. Additionally, 5 major wildland fires occurred in or around the City of Corona that threatened the community. A list of historical disasters for City is included in table 3.4.1.
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Figure 3.4.1 - Historical List of Disasters for City of Corona 24 LOCAL HAZARD MITIGATION PLAN
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Figure 3.4.1 - Historical List of Disasters for City of Corona (Continued) 25 LOCAL HAZARD MITIGATION PLAN
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3.5 MITIGATION PROJECT UPDATES
Since the adoption of the 2017 LHMP, the City of Corona has undertaken several measures and completed several projects to lessen the impact of disasters and prevent the loss of life and property. Some of these mitigation actions are identified in table
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Figure 3.5.1 – Mitigation Projects Completed
Hazard Type Project Description Status
All Incorporated 2012 Approved Local Hazard Mitigation Plan with City of Corona General Plan Complete
Fire, Water Supply
Disruption
Updated Booster Station buildings to current fire standards (Kraft Ranch, Montana Ranch,SDO, Maybe Canyon,Eagle Glen, Harlin Hills)
Complete
Fire Purchased 6 portable booster stations for emergency fire response
Complete
Earthquake
All above ground steel storage reservoirs were evaluated to ensure proper venting in the event of an earthquake.
Modifications were made where needed.
Complete
Earthquake, Electrical
Failure
Installation of emergency generators for 3 groundwater well sites. Complete
Electrical Failure,
Emergent Disease
Contamination
Emergency generators installed at all lift stations, plus a portable sewage lift station for emergency bypass Complete Flood Annual maintenance service on storm drains Complete Flood Construction of Main St storm drain. Alleviate flooding from 11th to 8th St. Complete
Flood Construction of Harris storm drain. Alleviate flooding on 6th St and apartments of 5th St.. Complete
Water Supply/
Contamination
Converted out of service well to a triple-nested monitoring well. Will increase local ground water supply. Complete Water Supply Disruption/
Contamination
Replaced 4,700 feet of 6 and 8 inch waterlines with 12 inch Ductile Iron Waterline pipe Complete
Flood Cota Channel restoration Complete
Terrorism
Became members of the BioWatch Program - BioWatch
provides early detection of biological agents in the air used for a bioterrorism attack
Complete
Terrorism
Corona PD & Fire established a Tactical Response to Violent Incidents Team and adopted the RCFCA Standard Operating Guidelines
Complete
Pandemic Flu
Partnered with Riverside County Public Health with the
development and implementation of the City of Corona
Pandemic Influenza Plan
Complete
HazMat, Transportation
Failure, Fire
2013 complete update to Hazardous Material Area Plan - to assist in the prevention or mitigation of damage from the release or threatened release of hazardous materials.
Complete
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Hazard Type Project Description Status
Water Supply Disruption/
Drought
2015 complete update to the Urban Water Management Plan - conservation and efficient water use Complete
Water Supply Disruption/
Drought
Instituted multiple residential water conservation programs, resulting in a nearly 20% reduction over the declared drought period
Complete
Flood/Water Supply
Contamination
2017 complete update to Sewer System Management Plan -
preventative maintenance, schedule, response plan Complete Transportation Failure 2012 development of Neighborhood Traffic Management Program Complete
Transportation Failure 2014 development of Corona Municipal Airport Emergency Plan Complete
Climate Change/Drought,
Emergent Disease
2012 developed the City of Corona Climate Action Plan - reduce GHG emissions Complete
Fire 2015 implementation of a Suppression Inspection Action Plan - facilitates the completion of hazard reduction inspections Complete HazMat, Fire
Contracted with G & G Environmental to ensure all on-site hazardous material inspections were completed within
required timeframe.
Complete
Communications
Failure/Fire
2015 complete update to the SOLAR - Multi-County Mutual Threat Zone Guide Complete
Communications
Failure/Fire
2015 update to the Corona Fire Radio Guide - Internal and external agency communications Complete
All
Fire Department Annual Master Training Plan - improves the safety and performance of Department's members in order for them to prevent or minimize loss of life, damage to the environment and loss of property.
Complete
All
2015 update to the Corona Fire Department Emergency
Medical Services Quality Improvement Program - delivery of consistent, high quality, compassionate pre-hospital patient care.
Complete
All
Police Department Annual Master Training Plan - improves the safety and performance of Department's members in order for them to prevent or minimize loss of life, damage to the environment and loss of property.
Complete
All 2017 implementation of the new Emergency Medical Dispatch Program - delivery of pre arrival medical direction Complete Figure 3.5.1 – Mitigation Projects Completed (Continued)
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CHAPTER 4.0 – HAZARD IDENTIFICATION AND RISK ASSESSMENT
4.1 CRITICAL FACILITIES AND INFRASTRUCTURE
A critical facility can be defined as one that is essential in providing utility or direction either during the response to an emergency or during the recovery operation. An inventory of critical facilities in the City of Corona is included in figures 4.1.1 and 4.1.2.
Figure 4.1.1 – Critical Facilities for City of Corona 2023 Critical Facilities Type Number
Public Safety Dispatch 1
Emergency Operations Center 1
City Services 2
Fire Stations 7
Water Reservoirs 15
Water Treatment Plants 3
Wastewater Treatment Plants 3
Hospitals 2
Police Facility 1
Maintenance Yards 1
Senior Care 26
Schools 44
Radio Repeaters 7
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Figure 4.1.2 Critical Facilities Map for City of Corona
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4.2 ESTIMATING POTENTIAL LOSS
The most vulnerable structures in the City are downtown, the Fire Station, City Hall, Cabot’s Pueblo Museum, and other unreinforced structures. These facilities are the weakest in the city. A major earthquake the proximity to the San Andreas Fault would also cause damage to any of these facilities due to their proximity to the San Andreas Fault.
4.3 TABLE OF REPLACEMENT VALUES
Figure 4.3.1 – Assets Table/Replacement Value for City of Corona
4.4 IDENTIFICATION OF RISKS AND VULNERABILITIES
The County of Riverside identified, evaluated, and ranked 23 natural and humaninduced public safety risks that could have an impact on the health, safety, and social well-being of the community. The ranking was based on severity of damage and probability of occurrence for each risk. The City of Corona then ranked the same 23 hazards and included the top 10 risks in the City’s annex to the Riverside County MJHMP. Below are the top 10 hazards in order of ranking. For a complete list of hazards, their probability and severity see Figure 3.2.1.
Name of Asset Replacement
Value ($)
Occupancy/
Capacity #
Hazard Specific
Info.
City Hall $45,094,961 N/A Unsecured
Perimeter
Fire Stations (7) $25,200,000 N/A Unsecured
Perimeters
Police Department $15,154,127 N/A Proximity to railroad Proximity to large
diameter gas line
Proximity to the
desalinization plant
Flight Path of
Corona Airport
Flood Zone
Emergency Operations Center $15,976,093 N/A Proximity to railroad 31 LOCAL HAZARD MITIGATION PLAN
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1. Earthquake
The City of Corona is seismically active, as is most of Southern California. Several known active or potentially active faults are in and around Corona.
The Elsinore Fault Zone is the closest major fault system to the City and one of the largest in Southern California. Historically, the Elsinore Fault Zone has also been one of the least active systems. At its northern end, near the City, the Elsinore Fault Zone splays into two segments, the Chino-Central Avenue Fault and the Whittier Fault. Along the southwestern portion of the City, the Elsinore Fault Zone is referred to as the Glen Ivy Fault. For more information on the faults zone around the city, please reference Figure 4.4.1.
Ground surface rupture due to active faulting is considered possible in the western portion of the City where known active or potentially active faults are mapped.
Geological evidence indicates that the Glen Ivy Fault and portions of the Whittier Fault are active and that the Chino-Central Avenue Fault is potentially active.
Historically, the Corona region has generally not been affected by a major, destructive earthquake. However, based on a search of earthquake databases of the United States Geological Survey (USGS) National Earthquake Information Center, several major earthquakes (magnitude 6.0 or more) have been recorded within approximately 100 kilometers of the City since 1769.
The City’s General Plan Public Health and Safety Element has identified various implementation programs with respect to fault rupture and other geologic disturbances. These programs specify various requirements including that detailed geologic investigations are to be conducted in conformance with guidelines of the California Division of Mines and Geology (CDMG) for all construction of transportation infrastructure in an Alquist-Priolo Special Study Zone and for construction of essential facilities within 200 feet of an active fault or potentially active fault. They also state that field information is to be developed as part of any California Environment Quality Act (CEQA) investigations and geologic reports by the City and/or County geologists should be kept current and accessible for use in report preparation, geologic reviews, and policy development.
Additionally, the City’s General Plan Public Health and Safety Element has identified various implementation programs to be carried out by the City and/or County affecting seismic safety of critical facilities.
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These programs include detailed site studies for faults are to be conducted as background to the design process for critical facilities under City and county discretionary approval as well as existing critical facilities are to be reviewed for any significant siting, design, or construction problems that would make them vulnerable in the event of an earthquake. The findings shall be incorporated into Emergency Operations Plans (EOPs) as well as addressed in longer-term programs of facilities upgrading or relocation unless satisfactorily demonstrated that a building setback from an active or potentially active fault will not adversely impact public health, safety, and welfare. New facilities deemed essential shall not be located within 200 feet of an active fault or potentially active fault. (See Riverside County OA MJHMP Section 4.0)
2. Wildland/Urban Fire
The combination of population density, weather, and growing residential and commercial development presents a potential year-round threat of conflagration.
However, late spring through early fall months is commonly referred to as the “fire season.”
The City of Corona is nearly surrounded by hills and mountains with the potential and the history of large wildland fires. To the south, the City sits at the base of the Santa Ana mountain range, and borders against the Cleveland National Forest. The shared boundary between the City and the Forest is about 12 miles in length. The fuels are heavy brush with oaks, sycamore and pines on the slopes and drainages.
Residential structures are immediately adjacent to this forest area throughout the entire boundary. Some are newer constructions with good clearances, and some are much older with less clearance.
The western portion of the City sits at the base of Prado Dam which is the headwater for the Santa Ana River Canyon. The Santa Ana Canyon’s steep topography and East-West alignment serve as a wind funnel. The geography increases the wind’s speed and magnifies the effects of fire on the available fuel bed, contributing to the rapid rate of fire spread. The northern side of this canyon comprises primarily light flashy fuels due to frequent burning and fuel typeconversion, and the southern side comprises primarily of heavy brush. There is a significant fire history in this canyon area. The 91 Freeway parallels the Santa Ana River throughout the canyon. There are areas of development where structures sit adjacent to wildland areas throughout the western areas of the City. 33 LOCAL HAZARD MITIGATION PLAN
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The northwest area of the City sits in the Prado Basin behind the Prado Dam and there are several developments that adjoin some heavy fuels.
The northeast area sits in the Corona Hills, and developments are built up to and on top of the hills. These hills comprise primarily of light flashy fuels due to frequent burning and type-conversion.
The eastern edge of the City is bordered by hills and Eagle Valley. This area has not been developed and is comprised of light flashy fuels due to frequent burning and type-conversion. Fires occur frequently, but there is very little structural threat.
In addition to interface areas within the City Limits, many of these areas also have significant residential development in unincorporated areas that are immediately adjacent to the City.
Over the years, there have been several significant fires, many of sizeable acreage, within the City or areas just outside its borders. Many of these fires have resulted in destroyed and damaged structures. There have been six state declarations for wildfire in Riverside County since the last LHMP update in 2017, and 34 federal declarations for Riverside County for wildfires, since 1990.
Weather
Weather patterns combined with certain geographic locations can create a favorable climate for wildfire activity. Areas where annual precipitation is less than 30 inches per year are extremely fire susceptible. High risk areas in Southern California share a hot, dry season in late summer and early fall when high temperatures and low humidity favor fire activity. The frequent occurrence of 40-50 mile per hour Santa Ana or foehn winds, coupled with temperatures more than 90 degrees, relative humidity of 20 percent or less and dense and extremely dry ground cover in inaccessible mountain or canyon areas causes the kinds of wildland fires Southern California experiences every year.
Topography
Topography has considerable effect on wildland fire behavior and on the ability of firefighters and their equipment to take action to suppress those fires.
Simply because of topography, a fire starting in the bottom of a canyon may expand quickly to the ridge top before initial attack forces can arrive. Rough topography greatly limits road construction, road standards, and accessibility by ground equipment.
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Steep topography also channels airflow, creating extremely erratic winds on leeward slopes and in canyons. Water supply for fire protection to structures at higher elevations is frequently dependent on pumping units. The source of power for such units is usually from overhead distribution lines, which are subject to destruction by wildland fires.
Vegetation
A key to effective fire control and the successful accommodation of fire in wildland management is the understanding of fire and its environment. Fire environment is the complex of fuel, topographic, and air mass factors that influence the inception, growth, and behavior of a fire. The topography and weather components are, for all practical purposes, beyond man’s control, but it is a different story with fuels, which can be controlled before the outbreak of fires. In terms of future urban expansion, finding new ways to control and understand these fuels can lead to possible fire reduction.
Of these different vegetation types, coastal sage scrub, chaparral, and grasslands reach some degree of flammability during the dry summer months and, under certain conditions, during the winter months.
For example, as chaparral gets older, twigs and branches within the plants die and are held in place. A stand of brush 10- to 20- years of age usually has enough dead material to produce rates of spread about the same as in grass fires when the fuels have dried out. In severe drought years, additional plant material may die, contributing to the fuel load.
Wildfire Characteristics
There are three categories of interface fire: The classic wildland/urban interface exists where well-defined urban and suburban development presses up against open expanses of wildland areas; the mixed wildland/urban interface is characterized by isolated homes, subdivisions and small communities situated predominantly in wildland settings; and the occluded wildland/urban interface exists where islands of wildland vegetation occur inside a largely urbanized area. Certain conditions must be present for significant interface fires to occur. The most common conditions include hot, dry and windy weather; the inability of fire protection forces to contain or suppress the fire; the occurrence of multiple fires that overwhelm committed resources; and a large fuel load (dense vegetation). Once a fire has started, several conditions influence its behavior, including fuel, topography, weather, drought and development. Southern California has two distinct areas of risk for wildland fire: the foothills and lower mountain areas which are most often 35 LOCAL HAZARD MITIGATION PLAN
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covered with scrub brush or chaparral and the higher elevations of mountains with heavily forested terrain.
Wildfire Hazard Areas
The State of California Department of Forestry and Fire Protection (CAL FIRE) is required by law to periodically map areas of significant fire hazards based on history, fuels, terrain, weather, and other relevant factors that influence fire potential and behavior. The fire hazard areas are delineated into zones known as Fire Hazard Severity Zones (FHSZ) that influence the construction of buildings and property protection to reduce the risks associated with wildland fires. In addition to areas of state responsibility, the map also displays areas where local governments have financial responsibility for wildland fire protection depicting moderate, high and very high delineations.
The Corona Fire Department collaborated with CAL FIRE in the development of our local Fire Hazard Severity Zone map. The Fire Chief approved the map on May 1, 2010, and it was adopted by the Corona City Council on May 19, 2010. See Figure 4.2.2 – Fire Hazard Zones.
The Fire Hazard Severity Zone Map will be used for:
Implementing wildland-urban interface building standards for new construction using the 2007 California Building Code, Section 7A (Wildland-Urban Interface).
Natural hazard real estate disclosure at the time of sale. One-hundred-foot defensible space clearance requirements around buildings.
Property development standards such as road widths, water supply and signage.
Reference for City and County General Plans.
3. Electrical Failure
Corona's electric utility was established on April 4, 2001, by City Council Resolution No. 2001-25 in response to state-wide rolling blackouts and electric price instability. The electric utility provides fully bundled electric service to City owned and operated facilities and eight areas within the City. It also provides energy delivery services to municipal and commercial customers within the City.
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Corona's electric utility was established on April 4, 2001, by City Council Resolution No. 2001-25 in response to state-wide rolling blackouts and electric price instability. The electric utility provides fully bundled electric service to City owned and operated facilities and eight areas within the City. It also provides energy delivery services to municipal and commercial customers within the City.
The current lack of back-up electricity at the City’s well sites leaves the City and its residents vulnerable to water service interruptions in the event of an electrical power failure. The Corona Department of Water and Power is responsible for the provision of water to more than 40,000 service connections. Currently, approximately half of the City's water is imported (via the Metropolitan Water District) and the other half is produced via local groundwater wells. Most (add %) of the City's groundwater wells do not have back-up generator power. This critical water source has great potential to be compromised by a power failure. A lack of pumping capability could interrupt water supply and delivery to thousands of residents. A power failure could deeply affect water supplies to residents, hospitals, and other essential facilities.
The loss of potable water is one of the most devastating effects from a natural disaster and can have long-term and lethal impacts. The lack of drinking water quickly leads to water-borne illness and dehydration and these conditions disproportionately affect the elderly, young and infirm.
The City’s above ground power lines are susceptible to the high winds that pass through the City. The potential for arcing lines causing sparks to drop onto buildings or brush is a hazard that the utility department continues to address, however there have been few major fires caused by this type of event. In addition to the overhead lines, there is a potential for events relating to underground vaults and power lines. These vaults and lines are susceptible to flooding during heavy rains as well as being broken by contractors digging in the streets and on property where underground utilities are used. (See Riverside County OA MJHMP Section 4.0)
4. Terrorist Event
Terrorism, as defined by the FBI, is "the unlawful use of force against persons or property to intimidate or coerce a government, the civilian population or any segment thereof, in the furtherance of political or social objectives. 37 LOCAL HAZARD MITIGATION PLAN
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The tactics of terrorism are diverse. As important as the actual attacks is the cultivation in the target population of the fear of such attacks, so that the threat of violence becomes as effective as actual violence. Terrorist tactics tend to favor attacks that avoid effective countermeasures and exploit vulnerabilities.
As such, terrorists have the potential to utilize many different types of tactics both conventional and unconventional. Some of these tactics include shootings, kidnappings, bombings, suicide attacks, bioterrorism, agroterrorism, nuclear terrorism, and cyberterrorism. From 2010 to 2022 there have been roughly 40 confirmed domestic terrorist incidents (See Riverside County OA MJHMP Section 4.0)
5. Water Supply Disruption/Contamination
The Corona Department of Water and Power is responsible for the provision of water, serving approximately 150,000 customers. Currently, approximately half of the City's water is imported (via the Metropolitan Water District) and the other half is produced via local groundwater wells. Most of the City's groundwater wells do not have back-up generator power. This critical water source has great potential to be compromised by a power failure. A lack of pumping capability could interrupt water supply and delivery to thousands of residents. A power failure could deeply affect water supplies to residents, hospitals, and other essential facilities. The loss of potable water is one of the most devastating effects from a natural disaster and can have long-term and lethal impacts.
The lack of drinking water quickly leads to water-borne illness and dehydration and these conditions disproportionately affect the elderly, young and infirm.
In addition, water reservoir failure could critically impair the City's fire fighting capabilities. The Corona Fire Department currently uses potable water for fighting fires.
Plans are in place for the recycled water to be utilized as new infrastructure is constructed and more water is treated for recycled use. However, city-wide availability of recycled water for firefighting is several years away.
On June 4, 2008, the Governor of the State of California proclaimed a condition of statewide drought and strongly encouraged local agencies to take aggressive, immediate action to reduce water consumption and prepare for potentially worsening conditions. Once again, conditions worsened and on January 17, 2014, California State Governor, Jerry Brown, declared a drought state of emergency. On April 17, 2017, Brown issued Executive Order B-40-17, officially ending the drought state of emergency in all California counties except Fresno, Kings, Tulare, and Tuolumne. 38 LOCAL HAZARD MITIGATION PLAN
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During these times the City of Corona adopted, implemented, and enforced water conservation programs to reduce the quantity of water used by consumers within the City to ensure that there was sufficient water for human consumption, sanitation, and fire protection. The City was diligent in conserving water, resulting in a nearly 20% reduction in Corona over the declared drought period.
The City is authorized to declare a water shortage emergency to prevail within its jurisdiction when it finds and determines that the City will not be able to or cannot satisfy the ordinary demands and requirements of water consumers without depleting the water supply of the City to the extent that there would be insufficient water for human consumption, sanitation, and fire protection.
6. Flood
Several creeks, washes, channels, and flood zones are contained in the Planning area of Corona. Areas of the City adjacent to the Santa Ana River, Temescal Creek and Mabey Canyon Wash are designated as Flood Zone A, which indicates the area is inundated by one percent annual chance flooding. Portions of the Planning Area surrounding the Temescal Wash, Main Street Wash, and the Arlington Channel have been designated as Flood Zone X500, which is inundated by 0.2 percent annual chance flooding. Other portions of the Planning Area are either designated as Flood Zone D, which is an area with undetermined possible flood hazards, or Flood Zone X, which lies outside the one percent and 0.2 percent annual chance flood plains. See Figure 4.7.2 – Flood Zones.
Several creeks, washes, channels, and flood zones are contained in the Planning area of Corona. Areas of the City adjacent to the Santa Ana River, Temescal Creek and Mabey Canyon Wash are designated as Flood Zone A, which indicates the area is inundated by one percent annual chance flooding.
Portions of the Planning Area surrounding the Temescal Wash, Main Street Wash, and the Arlington Channel have been designated as Flood Zone X500, which is inundated by 0.2 percent annual chance flooding. Other portions of the Planning Area are either designated as Flood Zone D, which is an area with undetermined possible flood hazards, or Flood Zone X, which lies outside the one percent and 0.2 percent annual chance flood plains. See Figure 4.7.2 – Flood Zones.
Temescal Wash has the highest flooding potential in the Corona Planning Area. Due to the size of the Temescal Watershed and the amount of rainfall received, several peak discharges have been recorded.
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Based on the stream gauge analysis data obtained from Flood Insurance Study dated September 30, 1992, the peak discharges for the 500-year, 100-year, and 10-year are 110,000 cfs (cubic feet per second), 25,000 cfs, 11,000 cfs, and 2,000cfs, respectively, for the 164-square mile watershed. These discharges are obtained from the Flood Insurance Study Report for Stream Gauge No. 11-720 near Corona above the 3M plant location.
The peak discharges are determined from the stream gauge data analysis, which is based on clear flow and existing conditions.
The Planning Area has experienced major flooding during periods of heavy runoff. The 1969 flooding in Temescal Wash caused extensive damage, which was determined to be higher than 100-year storm levels. Major flooding in the Planning Area could occur along the Temescal Wash and in west Corona, and storm sheet flows would produce a variety of damage depending upon the location. This sheet flow would be the result of overflows from the Oak Street Channel, Lincoln Avenue drain, Main Street Channel, Buena Vista drain, and Taylor Avenue drain. Other significant flooding areas are found along the open channel facilities near the City Yard. These facilities are determined to be inadequate for the 2-year storm event.
Several flood control projects including the Main Street Channel and Arlington Channel have been built in the Planning Area to help lessen the severity of heavy flooding.
The City of Corona participates in the National Flood Insurance Program (NFIP), as administered through the Federal Emergency Management Agency (FEMA).
Consequently, property owners can purchase Federal Flood Insurance.
In turn, the City of Corona has identified flood hazard areas and protective controls, including land use planning measures to reduce the potential risk of flood damage to property and loss of human life. (See Riverside County OA MJHMP Section 4.0)
7. Emergent Disease/Contamination
Infectious diseases have for centuries ranked wars and famine as major challenges to human progress and survival. They remain among the leading causes of death and disability worldwide. Against a constant background of established infections, epidemics of new and old infectious diseases periodically emerge, greatly magnifying the global burden of infections. Studies of these emerging infections reveal the evolutionary properties of pathogenic microorganisms and the dynamic relationships between microorganisms, their hosts and the environment.
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Climate change may well be the pre-eminent challenge of our time and it is already having a significant and measurable impact on California’s environment.
Climatic factors influence the emergence and reemergence of infectious diseases, in addition to multiple human, biological, and ecological determinants.
Climatologists have identified upward trends in global temperatures and now estimate an unprecedented rise of 2.0°C by the year 2100. Of major concern is that these changes can affect the introduction and dissemination of many serious infectious diseases.
The incidence of mosquito-borne diseases, including malaria, dengue, and viral encephalitis, are among those diseases most sensitive to climate. Climate change would directly affect disease transmission by shifting the vector's geographic range and increasing reproductive and biting rates and by shortening the pathogen incubation period. Climate-related increases in sea surface temperature and sea level can lead to higher incidence of water-borne infectious and toxin-related illnesses, such as cholera and shellfish poisoning. Human migration and damage to health infrastructures from the projected increase in climate variability could indirectly contribute to disease transmission. Human susceptibility to infections might be further compounded by malnutrition due to climate stress on agriculture and potential alterations in the human immune system caused by increased flux of ultraviolet radiation.
8. Transportation Failure
The City of Corona’s extensive transportation network which includes state highways, public transit, rail lines, and municipal airport provide additional associated incident risks that may cause severe injuries and/or deaths. Two major freeways and one railroad transect Corona. The Riverside Freeway (SR-91) runs east/west directly north of the City’s center, Interstate 15 (I-15) runs north/south near the eastern edge of the City.
Along with the potential for death and injuries from large-scale motor vehicle accidents, there is the potential for hazardous material spills or fires as numerous commercial transportation vehicles travel the highways and freeways with various types and quantities of hazardous materials.
The BNSF Railroad parallels SR-91, it is a strictly commercial freight transportation system. Large quantities and numerous types of hazardous materials are transported through Corona by rail daily.
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These corridors are major transportation routes to the economic center of Orange County from the Inland Empire. The primary hazard with rail service has not been any train vs. train or track derailments. There continues to be a large number of train v. vehicle or train v. pedestrian accidents in the City.
These accidents have caused both traffic and rail service delays. The danger with these types of accidents is that they can create train derailments or accidents when the train impacts with a vehicle or when the train engineer attempts to stop the train quickly.
The Corona Municipal Airport is home to 350-400 general aviation aircraft and is strictly a recreational airport with no commercial flights. Although small, the airport is extremely active, with approximately 50,000 annual operations. The City's transportation network of roads, freeways, rail lines and airport has been a priority in the city’s planning and mitigation efforts.
A Traffic Safety Plan has been implemented for the management of traffic events that occur in the City. Public Works, Police, and Fire have identified routes through the city to mitigate traffic issues that might occur. Command Posts, staging areas and other aspects of Incident Command have been addressed in the Traffic Safety Plan.
9. Communication Failure
One of the most immediate and significant impacts of disasters is the sudden and widescale breakdown or interruption of communications infrastructure.
When public communication networks fail, the impact can be widely felt and can wipe out access to standard mobile or landline telecommunications, in addition to Internet, fiber-optic cables, and even satellite-based emergency communication devices.
Whether these systems are completely or just partially knocked offline, communications systems during a disaster can be the difference between life and death for those affected. Locating those who may be trapped or injured becomes nearly impossible for emergency responders, and rescue efforts are further complicated by the inability to coordinate via standard methods of communication.
In addition to disruptions caused by physical damage you will more than likely encounter network congestion. When disaster strikes, the “pipes” that make up our communications networks often become congested with exceptionally high levels of data traffic, as those impacted seek to contact family and friends, emergency personnel work to coordinate relief efforts, and hundreds more upload pictures and videos of the damage.
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Aggregation hubs are often the failure point for congested networks. This occurs when data from several smaller sources flows into a central processing point and creates bottlenecks. When this happens, communication can be severely limited or cut off completely.
Consequences from these communication infrastructure failures can greatly affect emergency response and lead to the spread of false information and confusion.
10. Pandemic Flu
An influenza pandemic is a global outbreak of a new influenza A virus. A novel influenza A virus is one that has caused human infection but is different from current seasonal human influenza A viruses spreading among people. Novel influenza A viruses can be viruses that originate in animals that gain the ability to infect humans or human viruses that change significantly to be different from current human seasonal influenza A viruses. Some novel flu A viruses are believed to pose a greater pandemic threat than others and are more concerning to public health officials because they have caused serious human illness and death and have been able to spread in a limited manner from person-to-person. Novel influenza A viruses are of extra concern because of the potential impact they could have on public health if they gained the ability to spread from person-to-person easily, triggering a pandemic.
Three subtypes of avian influenza A viruses H5, H7 and H9, along with variant viruses H1N1v, H3N2v and H1N2v are currently most concerning to public health officials. In September 2009, the H1N1 influenza received worldwide attention as a threat to public health. Cases of death related to the H1N1 flu surfaced first in Riverside County, as the illness spread throughout the State as well as the Nation. The City was not exempt and had cases emerge at local schools. Conference calls with the County Health Officer, local government and school officials, and emergency managers helped the City to prepare for the threat of a pandemic emergency. Subsequently, the City of Corona took measures to mitigate and adopted a Plan for Pandemic emergencies. (See Riverside County OA MJHMP Section 4.0)
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Figure 4.4.1 – Earthquake Fault Zones for City of Corona 44 LOCAL HAZARD MITIGATION PLAN 2022 – 2027 CITY OF CORONA .
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Figure 4.4.2 – Flood Zones for City of Corona
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Figure 4.4.3 – Fire Hazard Zones for City of Corona
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SECTION 5.0 – COMMUNITY RATING SYSTEM
5.1 REPETITIVE LOSS PROPERTIES
The National Flood Insurance Program's (NFIP) Community Rating System (CRS) is a voluntary incentive program that recognizes and encourages community floodplain management activities that exceed the minimum NFIP requirements.
As a result, flood insurance premium rates are discounted to reflect the reduced flood risk resulting from the community actions meeting the three goals of the CRS:
1. Reduce flood losses.
2. Facilitate accurate insurance rating; and
3. Promote the awareness of flood insurance.
5.2 NATIONAL FLOOD INSURANCE PROPERTIES
The City of Corona has participated in the National Flood Insurance Program since 1978.
a. Describe participation in NFIP, including any changes since previously approved plan. Corona’s recent activity related to NFIP includes updated Riverside County Flood Insurance Study and digitized Flood Insurance Rate Maps (FIRM) on August 28, 2008. City of Corona Floodplain Management Ordinance updated on December 3, 2008.
b. Date first joined NFIP - May 15, 1978
c. Identify actions related to continued compliance with NFIP – Corona Floodplain Management Ordinance was updated in 2008 to meet the minimum NFIP requirements pursuant to Title 44 Code of Federal Regulations Sections 59,
60.3-60.6, and 65.3 and the California Department of Water Resources (DWR) Model Ordinance. The Public Works Department reviews development permit applications and plans to ensure they are following our Ordinances and requires map revisions as necessary and maintains records such as elevation certificates, Letters of Map Changes, and Flood Insurance Rate Maps (FIRMs) for public availability. The Community Services and Public Works Department investigate violations and issue enforcement orders to bring developments in compliance with City Ordinances.
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d. CRS member – No
e. CRS class – n/a
f. Describe any data used to regulate flood hazard area other than FEMA mapsRiverside County Flood Insurance Study issued August 28, 2008; Drainage studies used to support CLOMR and LOMR issuance.
g. Have there been issues with community participation in the program? No h. What are the general hurdles for effective implementation of the NFIP? Funding for updating outdated drainage studies and for performing new studies in previously unstudied flood hazard areas.
i. Summarize actions related to continued compliance with NFIP –See item Above.
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SECTION 6.0 - CAPABILITIES ASSESSMENT
The City’s ability to reduce hazards by improving upon existing mitigation strategies or implementing newly identified mitigation strategies, include it’s legal and regulatory authorities, administrative, technical, and fiscal capabilities, and imperative to the success of all these strategies, are its continuous outreach, education, and partnership building capabilities.
6.1 REGULATORY MITIGATION CAPABILITIES
The City formally adopts, reviews, and updates regulatory policies and plans, along with implementing regulations such as zoning and subdivision ordinances. The City partners and coordinates with Riverside County Operational Area to ensure we are apprised of all regional efforts, and adhere to State and Federal mandates.
The hazard mitigation plan update process provides the City with an opportunity to review, evaluate, and expand on existing policies, plans, and city programs. Figure 6.1.1. is an example of regulatory capabilities that assist the City in mitigation strategies.
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Figure 6.1.1 Regulatory Mitigation Capabilities for City of Corona 53 LOCAL HAZARD MITIGATION PLAN
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6.2 ADMINISTRATIVE AND TECHNICAL MITIGATION CAPABILITIES The figure below shows City personnel responsible for activities related to hazard mitigation. Expertise is used in hazard mitigation identification, planning and strategies, and where information is shared across various City plans.
Figure 6.2.1 Administrative and Technical Mitigation Capabilities for Corona
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6.3 FISCAL MITIGATION CAPABILITIES
The figure below identifies financial tools and resources the City could potentially use to help fund mitigation activities. City continually identifies potential Federal and State grant opportunities to supplement mitigation financial capabilities. See Section 6.5 Funding Opportunities.
Figure 6.3.1 - Fiscal Mitigation Capabilities for City of Corona Financial Resources
Accessible/Eligible
to Use (Yes/No) Comments
Community Development Block
Grants
Yes Depending on budget &
grantor approval
Capital improvements project
funding
Yes Depending on available
budget
Authority to levy taxes for
specific purposes
Yes With voter/city council
approval
Fees for water, sewer, gas, or
electric services
Yes With voter/city council
approval
Impact fees for new
development
Yes With city council
approval
Incur debt through general
obligation bonds
Yes With voter/city council
approval
Incur debt through special tax
bonds
Yes With voter/city council
approval
Incur debt through private
activities
No With voter/city council
approval
Withhold spending in hazard
prone areas
n/a With voter/city council
approval
6.4 MITIGATION OUTREACH AND PARTNERSHIPS
The City of Corona has an active emergency preparedness, education, and outreach program. Mitigation strategies are taught throughout the year at various community events, fairs, schools, businesses, and other functions. The greatest outreach efforts are being conducted through our CERT Program.
We coordinate with local profit, non-profit, volunteer, and special district entities, such as the school district, the hospital, and the American Red Cross in addition to our Operational Area partners and their volunteer organizations, to plan for and participant in all hazards joint training and exercises. The vast array of knowledge and resources these entities bring to the table greatly improves our emergency management capabilities.
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An example of these coordinated planning and training efforts is our city’s participation in the regional mass care and shelter planning as we incorporate planning for access and functional needs individuals. In addition, the city has designated cooling and warming centers to utilize during severe weather emergencies, when the establishment of a shelter is not necessary.
One of the most successful systems used to improve upon and augment our City’s capabilities and resources is our participation and partnership in the various mutual aid systems. Our Police and Fire Departments participate in mutual aid agreements in the event the City’s forces are stretched beyond their capabilities. California Emergency Management Agency coordinates the Emergency Management Assistance Act for the response of emergency management resources to assist in the management of emergencies and disasters. Our Corona Department of Water and Power participates in Cal WARN and the local ERNIE water resource mutual aid organizations. The City manages emergencies under the National Incident Management System (NIMS) which utilizes the Master Mutual Aid concept.
6.5 FUNDING OPPORTUNITIES
In addition to the fiscal capabilities identified in figure 6.3.1 – Fiscal Mitigation Capabilities for City of Corona, some of the greatest funding opportunities come in the form of State and Federal grants, such as the Hazard Mitigation Grant Program.
The Hazard Mitigation Grant Program (HMGP) is authorized by Section 404 of the Robert T. Stafford Disaster Relief and Emergency Assistance Act, as amended (the Stafford Act), Title 42, United States Code (U.S.C.) 5170c. The key purpose of HMGP is to ensure that the opportunities to take critical mitigation measures to reduce the risk of loss of life and property from future disasters are not lost during the reconstruction process following a disaster. HMGP is available, when authorized under a Presidential major disaster declaration, in the areas of the State requested by the Governor. The amount of HMGP funding available to the Applicant is based upon the total Federal assistance to be provided by FEMA for disaster recovery under the Presidential major disaster declaration.
The City of Corona applies for various grants to augment our mitigation financial capabilities. Examples of successful grants awarded to the City to assist in our mitigation efforts are as follows.
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1. The city applied for and received a grant award from the California Department of Water Resources (DWR) Flood Emergency Response Projects – Statewide Grant Round Two. The grant provided funding for the city to prepare the Flood Emergency Response Plan, develop, and conduct a tabletop and functional training exercise to test the plan and prepare the city and other participating agencies for flood response (a flood in the city can be caused by both a storm event and dam failure). The plan development is underway and will be completed in December 2018.
2. The city applied for and was awarded Hazard Mitigation Grant Program #4653-307-01R funding for a hydro-seeding project in the burn scar of the 2017 Canyon Fire. The approved activity is to hydro-seed 200,000 square feet of fire damaged area behind a residential area bordering 48 homes and infrastructure using an endemic mixture of California Native Species. The reestablishment of ground cover will assist in the prevention of or lessening the effects of erosion, flash flooding and debris flow. This project was completed by October 2018
SECTION 7.0 - MITIGATION STRATEGIES
7.1 GOALS AND OBJECTIVES
The City of Corona coordinated through the Riverside County Emergency Management Department and other multiple cities and agencies throughout Riverside County in the creation/update of the LHMP. The cooperation and discussions both in regional meetings, community outreach, and internal meetings allowed a global perspective and local jurisdictional perspective to identify additional exposures and hazards within Corona.
Goal 1: Reduce loss of life and injuries.
Objective 1.1: Provide timely notification and direction to the public in preparation for and response to imminent and potential hazards.
Objective 1.2: Protect public health and safety through mitigation, preparing for, responding to, and recovering from the effects of natural, technological, or man-made disasters.
Objective 1.3: Reduce hazard impacts and protect life, property, and the environment from damage.
Goal 2: Reduce Hazard Related Property Losses
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Objective 2.1: Encourage new development to occur in locations that avoid or minimize exposure to hazards.
Objective 2.2: Reduce hazard related property losses by enforcing strong building, fire, and municipal codes.
Objective 2.3: Reduce repetitive losses for fire, flood, and earthquakes by encouraging protective measures and by anticipating future events.
Objective 2.4: Reduce hazard impacts to critical facilities, utilities, and services through the implementation of mitigation strategies.
Objective 2.5: Continue to strengthen land use regulations in high hazard areas.
Goal 3: Protect the environment
Objective 3.1: Mitigate the impact of recurring drought conditions that impact both ground water supply and the agricultural industry.
Objective 3.2: Protect the environment from hazardous material releases or exposures.
Objective 3.3: Protect the environment from sewage, wastewater, and storm water pollution or contamination.
Goal 4: Improve coordination and collaboration with City Departments and partnering agencies throughout all phases of emergency management.
Objective 4.1: Coordinate with County EMD, Cal OES, and FEMA to ensure SEMS/NIMS compliancy and to ensure any updates or changes are instituted.
Objective 4.2: Improve City’s ability for continuity of operations for all hazard incidents.
Objective 4.3: Incorporate mitigation related activities into other disaster planning mechanisms, such as the General Plan and Capital Improvement Plan.
Objective 4.4: Participate in Operational Area meetings, committees, and exercises.
Goal 5: Improve Community and Agency Awareness
Objective 5.1: Improve mitigation and hazard related outreach to the public, businesses, and other stakeholders to increase their
understanding of the various types, locations and effects of hazards and vulnerabilities, and actions they can take to reduce those hazard impacts.
Objective 5.2: Improve, standardize, and expand the emergency preparedness education and outreach program.
7.2 MITIGATION ACTIONS
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The City of Corona identified the following mitigation actions to be taken based on the Goals and Objectives established, pertinent to the hazard ranking assessment.
These actions are in addition to the on-going mitigation strategies identified in Section
7.3 and the projects to be completed in the comprehensive Five-Year Capital Improvement Program (CIP), which provides for the maintenance and improvement of the City’s infrastructure.
The following mitigation projects have been identified by the responsible city department, scheduled and a funding mechanism has been allocated. 1) Goal 4: Improve coordination and collaboration with City Departments and partnering agencies throughout all phases of emergency management.
Objective 4.2: Improve City’s ability for continuity of operations for all hazard incidents.
Action: Enhance communication interoperability by purchasing Harris Unity Radios; these radios will operate on the Public Safety Enterprise Communications
10. Responsible Dept: Police Department
Mitigated Hazard: Communications Failure
Status: In progress
Funding: FY 17 State Homeland Security Program
2) Goal 1: Reduce loss of life and injury.
Objective 1.1: A Provide timely notification and direction to the public in preparation for and response to imminent and potential hazards.
Action: Replace/upgrade current Computer Aided Dispatch system which has been in place for over 30 years.
Responsible Dept: Police Department
Mitigated Hazard: All
Status: In progress will be completed in January 2023.
Funding: City General Fund
3) Goal 3: Protect the environment.
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Objective 3.2: Protect the environment from hazardous material releases or exposures.
Action: The 2021 Hazardous Materials Area Plan was updated in coordination with Riverside County Environmental Health to assist in the prevention or mitigation of damage from the release or threatened release of hazardous materials.
Responsible Dept: Fire Department
Mitigated Hazard: HazMat, Fire
Status: Updates to the plan have been completed and it is with the State for review. The approved plan will be taken to the Council for formal adoption in October 2018.
Funding: City General Fund
4) Goal 1: Reduce loss of life and injuries.
Objective 1.3: Reduce hazard impacts and protect life, property, and the environment from damage.
Action: Conduct Active Shooter exercises Citywide. Enter scene under force protection to provide care to victims that otherwise would have died from preventable death injuries.
Responsible Dept: Police and Fire Department
Mitigated Hazard: Terrorism
Status: Quarterly exercises beginning May 2023 into 2024/2025 Funding: City General Fund
5) Goal 2: Reduce Hazard Related Property Losses
Objective 2.3: Reduce repetitive losses for fire, flood, and earthquakes by encouraging protective measures and by anticipating future events.
Action: Department of Water and Power in conjunction with Emergency Management Division will facilitate the creation of a flood plan for the City of Corona
Responsible Dept: Department of Water and Power and Fire Department Mitigated Hazard: Flood
Status: Plan completed in December 2018
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Funding: California Dept. of Water Resources – Flood Emergency Response Projects – Statewide Grant
6) Goal 2: Reduce Hazard Related Property Losses
Objective 2.3: Reduce repetitive losses for fire, flood, and earthquakes by encouraging protective measures and by anticipating future events.
Action: Design and construction of Corona MDP Line 52 to alleviate flooding on Grand Avenue and Joy Street
Responsible Dept: Department of Water and Power
Mitigated Hazard: Flood
Status: Completed in November 2018
Funding: City General Fund – Capital Improvement Project 7) Goal 3: Reduce Hazard Related Property Losses
Objective 2.2: Reduce hazard related property losses by enforcing strong building, fire, and municipal codes.
Action: Ensure new development in the fire hazard severity zones follows Chapter 49 of the Fire Code and all other applicable codes. A separate fuel modification plan to be submitted for review and approval by the Fire Department Responsible Dept: Fire Department/Prevention
Mitigated Hazard: Fire
Status: Ongoing and continuous
Funding: Permit and inspection fees
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8) Goal 4: Improve Community and Agency Awareness
Objective 5.1: Improve mitigation and hazard related outreach to the public, faithbased organizations, businesses, and other stakeholders to increase their understanding of the various types, locations and effects of hazards and vulnerabilities, and actions they can take to reduce those hazard impacts.
Action: Provide Community Emergency Response Team training to the community. Offer this training twice a year to the community.
Responsible Dept: Fire Department/Emergency Management Division Mitigated Hazard: All
Status: Two classes a year. One in English, and one in Spanish.
Funding: State Homeland Security Program grant funding. 9) Goal 5: Improve coordination and collaboration with City Departments and partnering agencies throughout all phases of emergency management.
Objective 4.3: Incorporate mitigation related activities into other disaster planning mechanisms, such as the General Plan and Capital Improvement Plan.
Action: Coordination with Caltrans, Riverside County Transportation Commission with the Corona Freeway Improvement Projects. These projects hope to reduce traffic, increase capacity and mobility.
- Interstate 15 corridor improvement project
- State Route 91 corridor improvement project
- State Route 91/SR-71 interchange improvement project
Responsible Dept: Public Works
Mitigated Hazard: Transportation Failure
Status: All projects completed by 2020
Funding: Caltrans District 8
10) Goal 6: Improve coordination and collaboration with City Departments and partnering agencies throughout all phases of emergency management.
Objective 4.2: Improve City’s ability for continuity of operations for all hazard incidents.
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Action: Develop a multi-year EOC training and exercise plan, enhancing the city's ability to respond and recover from all hazard incidents, lessening the negative impacts to our residents.
Responsible Dept: Fire Department/Emergency Management Department Mitigated Hazard: All
Status: EOC Training began in March of 2023, with regular exercises.
Funding: City General Fund
7.3 ON-GOING MITIGATION STRATEGY PROGRAMS
The City of Corona has implemented and or updated several policies, procedures, programs and plans to lessen the impact of disasters and prevent the loss of life and property. Some of these on-going mitigation efforts are identified in the table below. 63 LOCAL HAZARD MITIGATION PLAN
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Figure 7.3.1 On-Going Mitigation Strategy Programs
Hazard Type Mitigation Action Mitigation Strategy
All 2017 LHMP Update and
annual review
Update 2012 Local Hazard Mitigation Plan to identify projects to lesson the impact of disasters and prevent the loss of life and property. Review to ensure priorities are not changed.
Contamination, Pollution,
Flood
Storm Water and Urban
Runoff Pollution
Prevention Program
Prevents pollution of local waterways, regulates what can be discharged into storm drains.
Terrorism BioWatch Program
Participant
BioWatch provides early detection of biological agents in the air used for a bioterrorism attack.
Transportation Failure,
Terrorism
Traffic Management
Center
Single location to monitor throughout the City over 70 traffic signals, 15 monitoring cameras and a video and data link between CalTrans District 8 TMC in San Bernardino.
Transportation Failure Advanced Traffic
Management System
Ability to make adjustments to timing of traffic signal systems on local streets and bottom of freeway ramps to assist in moderating congestion.
Terrorism
Train and Exercise PD &
Fire Tactical Response
Team
Enter scene under force protection to provide care to victims that otherwise would have died from preventable death
injuries.
HazMat, Transportation
Failure, Fire
Hazardous Material Area
Plan
Hazardous Material Area Plan, assists in the prevention or mitigation of damage from the release or threatened release of hazardous materials.
Pandemic Flu Pandemic Influenza Plan
City of Corona Pandemic Influenza Plan facilitates
coordination with County Public Health for an organized and quick response to a pandemic effecting the City, lessening the Fire, Transportation
Failure, Terrorism Emergency Airport Plan
Corona Municipal Airport Emergency Plan, provides agency coordination, communication procedures and lines of
authority.
Flood/Water Supply
Contamination
Sewer System
Management Plan
Sewer System Management Plan, outlines preventative
maintenance, schedule of maintenance and response plan.
Water Supply Disruption/
Drought
Urban Water Management
Plan
Urban Water Management Plan - conservation and efficient water use
Climate Change/Drought,
Emergent Disease
Climate Action Plan Climate Action Plan - identifies and implements actions to reduce GHG emissions.
Fire Suppression Inspection
Action Plan
Suppression Inspection Action Plan - facilitates the
completion of hazard reduction inspections.
HazMat, Fire
G&G Environmental
Contract
Conduct on-site inspections for businesses housing hazardous materials to ensure compliance of State, County and local policies and procedures.
Communications
Failure/Fire
SOLAR/Multi - County
Mutual Threat Zone Guide
Continued participation with the SOLAR group in contingency planning for communications, resources and response to
mutual threat areas.
All Fire & PD Annual Master
Training Plan
Improves the safety and performance of Department's
members in order for them to prevent or minimize loss of life, damage to the environment and loss of property.
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7.4 FUTURE MITIGATION STRATEGIES
Below are identified mitigation strategies. A funding source has either not yet been identified for these projects or the project is only partially funded. The City of Corona is continuously looking for funding opportunities to augment its financial mitigation capabilities.
For example, the city has submitted Notice of Intents in the hopes of being successful recipients of Hazard Mitigation Grant funds, because of FEMA-4305-DR. If we are not successful in our efforts, we will continue to pursue available funding opportunities and will utilize, when available, financial resources identified in 6.3 Fiscal Mitigation Capabilities. If funding can be secured, we will move forward with the following projects.
The City will continue to foster and develop Review Cooperative Agreements with the Cities of Norco, Riverside, and Eastvale in connection with hazard mitigation projects, outreach, and preparedness.
1) Goal 2: Reduce Hazard Related Property Losses
Objective 2.4: Reduce hazard impacts to critical facilities, utilities, and services through the implementation of mitigation strategies.
Action: Purchase and install back-up generators at City’s groundwater wells and blend station
Responsible Dept: Department of Water and Power
Mitigated Hazard: Electrical Failure, Water Supply Disruption, Earthquake Status: Not started
Funding: Submitted Notice of Intent for Hazard Mitigation Grant Funds 2) Goal 2: Reduce Hazard Related Property Losses
Objective 2.4: Reduce hazard impacts to critical facilities, utilities, and services through the implementation of mitigation strategies.
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Action: Ensure the city’s oldest fire stations with ages ranging from 30 to 50 years of service can withstand a significant seismic event. Station 2 will be replaced by the end of 2025 by the American Rescue Plan federal grant.
A comprehensive fire facility assessment will be completed by the fall of 2024 for overall capital improvement for the other 6 stations. Seven fire stations currently exist.
Responsible Dept: Fire Department
Mitigated Hazard: Earthquake
Status: In Progress
Funding: Federal Grant Funds
3) Goal 2: Reduce Hazard Related Property Losses
Objective 2.4: Reduce hazard impacts to critical facilities, utilities, and services through the implementation of mitigation strategies.
Action: Conduct maintenance identified in the Caltrans bridge inspection reports.
The passing of SB 1 will provide the City funding for repairs to roads and bridges.
Allocation of funds and priorities of projects have not yet been determined.
Responsible Dept: Public Works
Mitigated Hazard: Transportation Failure, Earthquake
Status: TBD
Funding: Senate Bill 1 funds not yet allocated
4) Goal 2: Reduce Hazard Related Property Losses
Objective 2.4: Reduce hazard impacts to critical facilities, utilities and services through the implementation of mitigation strategies.
Action: Conduct inspections of older water treatment facilities to ensure the ability to handle a seismic event and address any deficiencies.
SECTION 8.0 – PLAN IMPLEMENTATION AND MAINTENANCE PROCESS Implementation and maintenance of this 2023 LHMP is critical to the overall success of hazard mitigation planning. This is the 4th step in the planning process. This chapter provides an overview of the overall strategy for plan implementation and maintenance, 66 LOCAL HAZARD MITIGATION PLAN
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and outlines the method and schedule for monitoring, updating, and evaluating the LHMP.
We will review the LHMP and assess:
The goals and objectives and address current and expected conditions. If the nature, magnitude, and/or type of risks have changed. Current resources for implementing the plan and exploring new resources. Implementation problems, such as technical, political, legal, or coordination issues with other agencies.
The outcomes to ensure they are in line with the expected outcome, if not we will modify plan.
Changes in Federal, State, or local ordinances, laws and regulations Involve the public by posting notices on websites and announcements during public meetings intent to review and update LHMP allowing for public comment and input.
If we discover changes that have occurred during the evaluation, we will update the LHMP Revision Page, and notify Riverside County EMD to update our Annex.
The Fire Department Emergency Services Division will coordinate the monitoring, evaluation, and update of the LHMP.
The City has incorporated the LHMP by adoption into the Safety Element of the City’s General Plan.
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SECTION 9.0 – INCORPORATION INTO EXISTING PLANNING
MECHANISMS
The City has incorporated the Local Hazard Mitigation Plan by adoption into the Safety Element of the City’s General Plan. The Safety Element includes discussion of fire, earthquake, flooding, and landslide hazards. Based on the ranking of hazards identified in the LHMP priority of mitigation projects to address these hazards will be determined and used in the development of the City’s Capital Improvement Plan.
In addition, the City has often developed plans, policies and adopted ordinance to assist in the mitigation of hazards identified in the LHMP. These mitigation efforts can be seen in the following figures:
See Figure 3.5.1 Mitigation Project Updates
See Figure 6.1.1 Regulatory Mitigation Capabilities
See Figure 7.3.1 On-Going Mitigation Strategy Programs
SECTION 10.0 - CONTINUED PUBLIC INVOLVEMENT
Continued public involvement is imperative to the overall success of the LHMP implementation. The update process provides an opportunity to solicit participation from new and existing stakeholders and to publicize success stories from the plan implementation and seek additional public comment. The LHMP maintenance and update process will include continued public and stakeholder involvement and input through attendance at City Council Meetings, Community Based Organization meetings, other meetings or events that may be scheduled, web postings, social media, and public hearings.
If any changes are made in the Scheduled Plan Maintenance Process, the public will be notified through actions taken at City Council meetings by posting of the agenda, cable TV viewing of these meetings, posting on the City’s website and outreach at community meetings.
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APPENDIX A – PUBLIC NOTICES AND MAPS
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Multi-Jurisdictional Local Hazard Mitigation Plan (MJLHMP) Update Steering Committee Meeting Minutes
Date: October 5, 2022
Time: 10:00 a.m. to 11:30 a.m.
Email Designated for LHMP: [email protected]
Brian MacGavin called the meeting to order and reviewed housekeeping items and meeting minutes from August 3, 2022.
Meeting Purpose: To provide a forum for MJLHMP participants to be able to share information and provide feedback into the oversight of the MJLHMP update process.
Review of Update / Requirements and timeline.
o Jennifer Smith reviewed the immediate update requirements and the MJLHMP timeline. o August-October: identify goals, objectives, and actions to take and have data compiled. o Inventory Worksheets and Risk Assessments should be completed by October 25 and mitigation actions should be finalized In November.
o A Teams meeting will be held with all county department representatives on October 25 to discuss completing Inventory and Risk Assessments that are due by October 25th.
Data Collection and HAZUS
o Breakdown of every risk category.
https://hazards.fema.gov/nri/map
o Risk Assessment Survey has been sent out.
Tracking and Scoring Mitigation Projects
o Brian MacGavin presented information on the tracking and scoring of mitigation projects. o A new spreadsheet will be formulated for 2023 mitigation projects and actions. o Separate spreadsheets will be reviewed as we go forward with the update.
Jurisdictional and County Department Assessments
o William Luna provided information on completing jurisdictional and county department assessments.
Additional Discussion and Feedback
o Something to do after plan is approved, going back and reviewing the definitions.
Next steps and Action Items
o Complete Inventory Worksheets and Risk Assessments.
o Contact Brian MacGavin, Jennifer Smith, or William Luna for assistance or questions.
Adjournment / Next Meeting
o Brian MacGavin adjourned the meeting and announced that the next meeting will be on January 4, 2023.
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Multi-Jurisdictional Local Hazard Mitigation Plan (MJLHMP) Update OA Steering Committee Agenda
Date: January 4, 2023
Time: 10:00 AM to 11:30 AM
Subject Time Presented by Purpose Attachments
Introductions / Housekeeping 10 mins Brian
MacGavin
Inform Sign-in Sheet
Review of Minutes from October 5, 2022 5 mins.
Brian
MacGavin
Inform October 5, 2022 Steering
Committee Minutes
Review of update requirements and timeline 10 mins.
Jennifer Smith Inform Local Mitigation Plan
Review Guide & Timeline
GIS / Data Collection 10 mins
Moses
Martinez
Information
2023-2028 Tracking and Scoring Mitigation
Projects / Actions 15 mins
Brian
MacGavin
Inform Mitigation Projects
Spreadsheet
Jurisdictional LHMP Status Reports 15 mins.
William Luna Information
Additional Discussion and Feedback from
Steering Committee Members 15 mins.
All Discuss N/A
Next Steps /Action Items 5 mins.
Brian
MacGavin
Discuss N/A
Adjourn / Next Meeting 2 mins.
Brian
MacGavin
Inform
N/A
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APPENDIX B – INVENTORY WORKSHEETS
RIVERSIDE COUNTY MULTI-JURISDICTIONAL
LOCAL HAZARD MITIGATION AGENCY
2023 INVENTORY WORKSHEETS
City of Corona
JUNE 2023
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TABLE OF CONTENTS
Introduction: These documents are meant to be discussed, used, and reviewed by a multi-disciplinary team. Participation by a wide range of stakeholders who play a role in identifying and implementing mitigation actions is required.
SPECIAL CONCERNS:
1. The completed Letter of Commitment has been returned to EMD.
2. The completed Letter of Participation has been returned to EMD.
1. Local Jurisdiction Contact Information Page 3
2. Hazard Identification Questionnaire Pages 4-6
3. Specific Hazards Summary Page 7
4. Jurisdiction Vulnerability Worksheet Pages 8-9
5. Jurisdiction Mitigation Strategies and Goals Pages 10-14
6. Local Jurisdiction Proposed Mitigation Action
and Strategy Proposal Pages 14-16
7. Local Jurisdiction Development Trends Pages 17-18
8. Appendix A-Plan Review Tool Pages A1-10
Appendix A the Plan Review Tool for your reference. This is the document Cal EMA and FEMA will utilize to verify that all the required information is in the submitted documents.
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1. LOCAL JURISDICTION CONTACT INFORMATION
The information on this page identifies:
Jurisdiction and the contact person
Jurisdiction's service area size and population
EOP Plan and a Safety Element of their General Plan
PLEASE PROVIDE THE FOLLOWING INFORMATION:
Agency/Jurisdiction: City of Corona
Type Agency/Jurisdiction: Local Government
Contact Person: Title: Emergency Services Manager
First Name: Lee Last Name: Shin
Agency Address: Street: 735 Public Safety Way
City: Corona
State: CA
Zip: 92880
Contact Phone 951-496-1299 FAX 951-736-2497
E-mail [email protected]
Population Served 167,759 Square Miles Served 39.2
Does your organization have a general plan? Yes
Does your organization have a safety component to the general plan? Yes What year was your plan last updated? 2018
Does your organization have a disaster/emergency operations plan? Yes What year was your plan last updated? 2023
Do you have a recovery annex or section in your plan? Yes Do you have a terrorism/WMD annex or section in your plan? Yes
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2. Hazard Identification Questionnaire
The purpose of the questionnaire is to help identify the hazards within your service area. The list was developed from the first round of meetings with the various working groups in the 2023 plan creation, and from the hazards listed in the County's General Plan. Each hazard is discussed in detail in Part I of the 2023 LHMP. The information will be used as the basis for each jurisdiction to evaluate its capabilities, determine its needs, and to assist in developing goals and strategies. The information identifies:
a) What hazards can be identified within or adjacent to the service area of the jurisdiction.
b) Which of those hazards have had reoccurring events.
c) What specific hazards and risks are considered by the jurisdiction to be a threat specifically to the jurisdiction? ( These locations should be identified by name and location for inclusion in the Specific Hazard Summary Table). a. Specific types of facilities owned and operated by the jurisdiction. b. Locations damaged from prior disasters or hazard causing events. d) Information about the jurisdiction's EOC
With your Multi-Disciplinary Planning Team:
a. Instructions for Updating Jurisdictions, with your planning team: Review your old Questionnaire for accuracy and relevance, mark changes. b. Instructions for New Jurisdictions and Special Districts, with your planning team, meet and go over the questionnaire. Fill in YES, NO or NA on the Questionnaire.
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HAZARD IDENTIFICATION QUESTIONNAIRE
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DOES YOUR ORGANIZATION HAVE:
AIRPORT IN JURISDICTION Yes
AIRPORT NEXT TO JURISDICTION No
DAIRY INDUSTRY No
POULTRY INDUSTRY No
CROPS/ORCHARDS No
DAMS IN JURISDICTION Yes
DAMS NEXT TO JURISDICTION Yes
LAKE/RESERVOIR IN JURISDICTION Yes
LAKE/RESERVOIR NEAR JURISDICTION Yes
JURISDICTION IN FLOOD PLAIN Yes
CONTROLLED FLOOD CONTROL CHANNEL Yes
UNCONTROLLED FLOOD CONTROL CHANNEL Yes
EARTHQUAKE FAULTS IN JURISDICTION Yes
EARTHQUAKE FAULTS NEXT TO JURISDICTION Yes
MOBILE HOME PARKS Yes
NON-REINFORCED FREEWAY BRIDGES No
NON-REINFORCED BRIDGES No
BRIDGES IN FLOOD PLAIN No
BRIDGES OVER OR ACROSS RIVER/STREAM Yes
ROADWAY CROSSING RIVER/STREAM No
NON-REINFORCED BUILDINGS No
FREEWAY/MAJOR HIGHWAY IN JURISDICTION Yes
FREEWAY/MAJOR HIGHWAY NEXT TO JURISDICTION Yes
FOREST AREA IN JURISDICTION No
FOREST AREA NEXT TO JURISDICTION Yes
WITHIN THE 50 MILES SAN ONOFRE EVACUATION ZONE Yes
MAJOR GAS/OIL PIPELINES IN JURISDICTION Yes
MAJOR GAS/OIL PIPELINES NEXT TO JURISDICTION Yes
RAILROAD TRACKS IN JURISDICTION Yes
RAILROAD TRACKS NEXT TO JURISDICTION Yes
HAZARDOUS WASTE FACILITIES IN JURISDICTION Yes
HAZARDOUS WASTE FACILITIES NEXT TO JURISDICTION Yes
HAZARDOUS STORAGE FACILITIES IN JURISDICTION Yes
HAZARDOUS STORAGE FACILITIES NEXT TO JURISDICTION Yes
DOES YOUR ORGANIZATION OWN OR OPERATE A FACILITY
IN A FLOOD PLAIN Yes
NEAR FLOOD PLAIN Yes
NEAR RAILROAD TRACKS Yes
NEAR A DAM Yes
UPSTREAM FROM A DAM Yes
DOWNSTREAM FROM A DAM Yes
DOWNSTREAM OF A LAKE Yes
DOWNSTREAM FROM A RESERVOIR Yes
NEAR A CONTROLLED FLOOD CONTROL CHANNEL Yes
NEAR UNCONTROLLED FLOOD CONTROL CHANNEL Yes
ON AN EARTHQUAKE FAULT Yes
NEAR AN EARTHQUAKE FAULT Yes
WITHIN THE 50 MILE SAN ONOFRE EVACUATION ZONE Yes
IN A FOREST AREA No
NEAR A FOREST AREA Yes
NEAR A MAJOR HIGHWAY Yes
A HAZARDOUS WASTE FACILITY Yes
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NEAR A HAZARDOUS WASTE FACILITY Yes
A HAZARDOUS STORAGE FACILITY Yes
NEAR A HAZARDOUS STORAGE FACILITY Yes
NON-REINFORCED BUILDINGS No
A MAJOR GAS/OIL PIPELINE No
NEAR A MAJOR GAS/OIL PIPELINE Yes
DOES YOUR ORGANIZATION HAVE ANY LOCATIONS THAT:
HAVE BEEN DAMAGED BY EARTHQUAKE AND NOT REPAIRED No
HAVE BEEN DAMAGED BY FLOOD Yes
HAVE BEEN DAMAGED BY FLOOD MORE THAN ONCE Yes
HAVE BEEN DAMAGED BY FOREST FIRE No
HAVE BEEN DAMAGED BY FOREST FIRE MORE THAN ONCE No
HAVE BEEN IMPACTED BY A TRANSPORTATION ACCIDENT Yes
HAVE BEEN IMPACTED BY A PIPELINE EVENT No
EMERGENCY OPERATIONS INFORMATION
DOES YOUR ORGANIZATION HAVE AN EOC Yes
IS YOUR EOC LOCATED IN A FLOOD PLAIN Yes
NEAR FLOOD PLAIN Yes
NEAR RAILROAD TRACKS Yes
NEAR A DAM Yes
UPSTREAM FROM A DAM Yes
DOWNSTREAM FROM A DAM Yes
DOWNSTREAM OF A LAKE Yes
DOWNSTREAM FROM A RESERVOIR Yes
NEAR A CONTROLLED FLOOD CONTROL CHANNEL Yes
NEAR UNCONTROLLED FLOOD CONTROL CHANNEL Yes
ON AN EARTHQUAKE FAULT No
NEAR AN EARTHQUAKE FAULT Yes
WITHIN THE 50 MILE SAN ONOFRE EVACUATION ZONE Yes
IN A FOREST AREA No
NEAR A FOREST AREA Yes
NEAR A MAJOR HIGHWAY Yes
A HAZARDOUS WASTE FACILITY Yes
NEAR A HAZARDOUS WASTE FACILITY Yes
A HAZARDOUS STORAGE FACILITY Yes
NEAR A HAZARDOUS STORAGE FACILITY Yes
NON-REINFORCED BUILDINGS No
A MAJOR GAS/OIL PIPELINE Yes
NEAR A MAJOR GAS/OIL PIPELINE Yes
OTHER FACILITY INFORMATION
ARE THERE LOCATIONS WITHIN YOUR JURISDICTION THAT:
COULD BE CONSIDERED A TERRORIST TARGET Yes
COULD BE CONSIDERED A BIO-HAZARD RISK Yes
With your planning team, list the “Yes” answers and discuss. Use the information as a group to summarize your jurisdiction’s hazards and vulnerabilities.
CITY OF CORONA 95
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3. SPECIFIC HAZARDS SUMMARY
This table helps to identify the information (name, owner, location, etc.) about the specific hazards identified in the Hazard Questionnaire.
In the Summary Table, list the basic information of the hazards identified by the jurisdiction in the Hazard Identification Questionnaire as a potential threat. These specific hazards were used in the development of response plans, maps, and other analysis data. a. Instructions for Updating Jurisdictions and Special Districts: With your planning team, review the “Yes” answers and see if there were any changes, if so, summarize why there is a difference from 2017 LHMP.
b. Instructions for New Jurisdictions and Special Districts: With your planning team, review the “Yes” answers and discuss. Use the information as a group to summarize your jurisdiction’s hazards and vulnerabilities.
SPECIFIC HAZARDS SUMMARY
Jurisdiction Hazard Type Hazard Name In
Jurisdiction?
Adjacent to
Jurisdiction?
Corona Dam Lake Mathews No Yes
Dam Prado No Yes
Fault Elsinore Yes Yes
Flood Channel Mabey Canyon Yes No
Flood Channel Temescal Creek Yes Yes
Hazmat Manufacturing Facility Downs Energy Yes No
Hazmat Manufacturing Facility Dart Containers Yes No
Hazmat Manufacturing Facility G & S Associates Yes No
Hazmat Manufacturing Facility Golden Cheese Yes No
Hazmat Manufacturing Facility GTM, Inc. Yes No
Hazmat Manufacturing Facility Hi-Country Yes No
Hazmat Manufacturing Facility Us Battery Yes No
Hazmat Manufacturing Facility Watson Pharmaceuticals Yes No Hazmat Storage Location Advanced Fuel Filtration Yes No Hazmat Storage Location All American Asphalt Yes No
Hazmat Storage Location Liston Aluminum Yes No
Hazmat Storage Location United Agri Products Yes No
Lake Lake Mathews No Yes
Pipeline Four Corners Oil Pipeline Yes No
Pipeline Natural Gas Yes No
Railroad Track BNSF Yes No
Reservoir Lake Mathews No Yes
River Santa Ana River No Yes
CITY OF CORONA 96
LOCAL HAZARD MITIGATION PLAN FEB 2023 4. JURISDICTION VULNERABILITY WORKSHEET This table is a listing of the primary hazards identified by the 2022 LHMP working groups. Each jurisdiction was asked to evaluate the potential for an event to occur in their jurisdiction by hazard. They were also asked to evaluate the potential impact of that event by hazard on their jurisdiction. The impact potential was determined based on:
1. Economic loss and recovery 2. Physical loss to structures (residential, commercial, and critical facilities) 3. The loss or damage to the jurisdiction’s infrastructure 4. Their ability to continue with normal daily governmental activities 5. Their ability to quickly recover from the event and return to normal daily activities 6. The loss of life and potential injuries from the event.
The jurisdictions were asked to rate the potential and severity using a scale of between 0 and 4 (4 being the most severe). Thejurisdictions were also asked to rank the listed hazards as they relate to their jurisdiction from 1 to 19 (1 being the highest overall threat to their jurisdiction). With the assistance of the RCIP Plan and County Departments, Riverside County EMD conducted an extensive evaluation of the severity and probability potential for the county. The hazards were also ranked for the County. Those numbers and rankings wereprovided to the jurisdictions as a comparison guide. A separate table was created to address the hazards relating to agriculture and was assessed by the agriculture working group. a. Instructions for Updating Jurisdictions and Special Districts: Please review the table, determine if you’re ranking from the 2017 LHMP remains the same, and note that Pandemic has been added to the list. Please discuss and document new or unchanged severity and rankings. b. Instructions for New Jurisdictions and Special Districts: Please evaluate the potential for an event to occur in your jurisdiction by hazard. Then, evaluate the potential impact of that event by hazard on your jurisdiction according to #1-6 from the potential impact list above.
NOTE: Under Medical, Pandemic was added. This was a result of the H1N1 and other incidents.
CITY OF CORONA 97
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NAME: City of Corona AGENCY: DATE: 2/20/2023
COUNTY CITY OF CORONA
HAZARD
SEVERITY
0 - 4
PROBABILITY
0 - 4
SEVERITY
0 - 4
PROBABILITY
0 - 4
RANKING
1 - 19
EARTHQUAKE 4 2 4 3 1 WILDLAND FIRE 3 4 3 3 2 FLOOD 3 3 3 3 6 OTHER NATURAL HAZARDS DROUGHT 3 3 3 3 12 LANDSLIDES 3 3 2 1 20 INSECT INFESTATION 2 3 1 1 18 EXTREME SUMMER/WINTER WEATHER 3 2 2 2 13 SEVERE WIND EVENT NAAGRICULTURAL DISEASE/CONTAMINATION 3 3 3 3 7 TERRORISM 3 1 4 2 4
OTHER MAN-MADE
PIPELINE 3 2 3 2 19
AQUEDUCT 3 2 2 2 22
TRANSPORTATION 3 2 3 2 8 POWER OUTAGE 4 4 4 4 3 HAZMAT ACCIDENTS 3 4 3 2 14 NUCLEAR ACCIDENT 4 1 4 1 17 TERRORISM 3 1 4 2 4 CIVIL UNREST 3 2 2 2 16 JAIL/PRISON EVENT 2 1 1 2 21 MEDICAL PANDEMIC 4 2 4 2 10
CITY OF CORONA 98
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CITY OF CORONA 99
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5. JURISDICTION MITIGATION STRATEGIES AND GOALS
This comprehensive table is a listing of the various mitigation strategies, goals, and objectives developed by the 2022 LHMP working groups.
The jurisdictions were also given the opportunity to list additional strategies, goals, and objectives CITY OF CORONA 100
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specific to their jurisdiction.
LOCAL JURISDICTION MITIGATION STRATEGIES AND GOALS
With your Planning Team
a. Instructions for Updating Jurisdictions and Special Districts: please review the table; determine if you’re ranking from the 2023 LHMP remains the same.
b. Instructions for New Jurisdictions and Special Districts: please follow below:
Please evaluate the priority level for each listed mitigation goal identified below as it relates to your jurisdiction or facility. If you have any additional mitigation goals or recommendations, please list them at the end of this document.
Place an H (High), M (Medium), L (Low), or N/A (Not Applicable) for your priority level for each mitigation goal in the box next to the activity.
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EARTHQUAKE
M Aggressive public education campaign in light of predictions M Generate new literature for dissemination to:
M ◊ Government employees
M ◊ Businesses
L ◊ Hotel/motel literature
M ◊ Local radio stations for education
M ◊ Public education via utilities
M ◊ Identify/create television documentary content
M Improve the Emergency Alert System (EAS)
M ◊ Consider integration with radio notification systems H ◊ Upgrade alerting and warning systems for hearing impaired H ◊ Training and maintenance
L Procure earthquake-warning devices for critical facilities H Reinforce emergency response facilities
N/A Provide training to hospital staffs
L Require earthquake gas shutoffs on remodels/new construction M Evaluate re-enforcing reservoir concrete bases
L Evaluate EOCs for seismic stability
H Install earthquake cutoffs at reservoirs
M Install earthquake-warning devices at critical facilities L Develop a dam inundation plan for new Diamond Valley Reservoir M Earthquake retrofitting
N/A ◊ Bridges/dams/pipelines
L ◊ Government buildings/schools
N/A ◊ Mobile home parks
L Develop educational materials on structural reinforcement and home inspections (ALREADY DEVELOPED) M Ensure Uniform Building Code compliance
M ◊ Update to current compliance when retrofitting
L Insurance coverage on public facilities
L Funding for non-structural abatement (Earthquake kits, etc.) L Pre - identify empty commercial space for seismic re-location L Electrical co-generation facilities need retrofitting/reinforcement (Palm Springs, others?) L Mapping of liquefaction zones
M Incorporate County geologist data into planning
N/A Backup water supplies for hospitals
M Evaluate pipeline seismic resiliency
M Pre-positioning of temporary response structures
M Fire sprinkler ordinance for all structures
L Evaluate adequacy of reservoir capacity for sprinkler systems L Training/standardization for contractors performing retrofitting L Website with mitigation/contractor/retrofitting information L ◊ Links to jurisdictions
M ◊ Alerting information
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L ◊ Volunteer information
M Evaluate depths of aquifers/wells for adequacy during quakes L Evaluate hazmat storage regulations near faults
COMMUNICATIONS IN DISASTER ISSUES
M Communications Interoperability
M Harden repeater sites
H Continue existing interoperability project
M Strengthen/harden
M Relocate
H Redundancy
M Mobile repeaters
FLOODS
L Update development policies for flood plains
L Public education on locations of flood plains
L Develop multi-jurisdictional working group on floodplain management L Develop greenbelt requirements in new developments
L Update weather pattern/flood plain maps
L Conduct countywide study of flood barriers/channels/gates/water dispersal systems M Required water flow/runoff plans for new development
M Perform GIS mapping of flood channels, etc.
L Install vehicular crossing gates/physical barriers for road closure H Maintenance of storm sewers/flood channels
M Create map of flood channels/diversions/water systems etc.
L Require digital floor plans on new non-residential construction M Upgrade dirt embankments to concrete
M Conduct countywide needs study on drainage capabilities H Increase number of pumping stations
L Increase sandbag distribution capacities
M Develop pre-planned response plan for floods
M ◊ Evacuation documentation
M ◊ Re-examine historical flooding data for potential street re-design L Training for city/county PIOs about flood issues
L Warning systems - ensure accurate information provided L ◊ Publicize flood plain information (website?)
L ◊ Install warning/water level signage
L ◊ Enhanced public information
L ◊ Road closure compliance
L ◊ Shelter locations
L ◊ Pre-event communications
L Look at County requirements for neighborhood access
L ◊ Secondary means of ingress/egress
M Vegetation restoration programs
M Ensure critical facilities are hardened/backed up
L Hardening water towers
L Terrorism Surveillance - cameras at reservoirs/dams
CITY OF CORONA 103
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M Riverbed maintenance
M Evaluate existing lift stations for adequacy
L Acquisition of property for on-site retention
M Evaluate regulations on roof drainage mechanism
M Erosion-resistant plants
L Traffic light protection
M Upkeep of diversionary devices
M Install more turn-off valves on pipelines
H Backup generation facilities
H Identify swift water rescue capabilities across County
WILDFIRES
M Aggressive weed abatement program
M ◊ Networking of agencies for weed abatement
N/A Develop strategic plan for forest management
H Public education on wildfire defense
M Encourage citizen surveillance and reporting
L Identify hydrants with equipment ownership information M Enhanced firefighting equipment
L Fire spotter program/red flag program
L ◊ Expand to other utilities
N/A Research on insect/pest mitigation technologies
L Volunteer home inspection program
L Public education program
L ◊ Weather reporting/alerting
M ◊ Building protection
L ◊ Respiration
M Pre-identify shelters/recovery centers/other resources M Roofing materials/defensive spacing regulations
M Community task forces for planning and education
M Fuel/dead tree removal
L Strategic pre-placement of firefighting equipment
L Establish FEMA coordination processes based on ICS
M Brush clearings around repeaters
L Research new technologies for identifying/tracking fires M Procure/deploy backup communications equipment
N/A "Red Tag" homes in advance of event
N/A Provide fire-resistant gel to homeowners
L Involve insurance agencies in mitigation programs
N/A Clear out abandoned vehicles from oases
H Code enforcement
H Codes prohibiting fireworks
H Fuel modification/removal
L Evaluate building codes
H Maintaining catch basins
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OTHER HAZARDS
N/A Improve pipeline maintenance
N/A Wetlands mosquito mitigation (West Nile Virus)
M Insect control study
N/A Increase County Vector Control capacities
H General public drought awareness
H ◊ Lawn watering rotation
N/A Develop County drought plan
H Mitigation of landslide-prone areas
N/A Develop winter storm sheltering plan
N/A Ease permitting process for building transmission lines L Evaluate restrictions on dust/dirt/generating activities during wind seasons N/A Rotational crop planning/soil stabilization
N/A Enhance agricultural checkpoint enforcement
N/A Agriculture - funding of detection programs
M Communications of pipeline maps (based on need to know) M Improved notification plan on runaway trains
M Improve/maintain blackout notification plan.
M Support business continuity planning for utility outages H Terrorism training/equipment for first responders
H ◊ Terrorism planning/coordination
M ◊ Staffing for terrorism mitigation
M Create a SONGS regional planning group
L ◊ Include dirty bomb planning
M Cooling stations - MOUs in place
N/A Fire Ant eradication program
N/A White Fly infestation abatement/eradication program M Develop plan for supplemental water sources
H Public education on low water landscaping
N/A Salton Sea desalinization
N/A Establish agriculture security standards (focus on water supply) M ID mutual aid agreements
M Vulnerability assessment on fiber-optic cable
N/A Upgrade valves on California aqueduct
L Public education
L ◊ Bi-lingual signs
L ◊ Power Outage information
M Notification system for rail traffic - container contents H Control and release of terrorism intelligence
N/A Develop prison evacuation plan (shelter in place?)
CITY OF CORONA 105
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Use the list and rankings to narrow down or identify “your” strategies.
The mitigation strategy serves as the long-term blueprint for reducing the potential losses identified in the risk assessment. The mitigation strategy includes the development of goals, objectives, and prioritized mitigation actions.
Goals are general guidelines that explain what you want to achieve. They are broad policy statements and are usually long-term and represent global visions, such as “Protect Existing Property.”
Objectives define strategies or implementation steps to attain the identified goals. Unlike goals, objectives are specific, measurable, and may have a defined completion date. Objectives are more specific, such as “Increase the number of buildings protected from flooding.” The development of effective goals and objectives enables the planning team to evaluate the merits of alternative mitigation actions and the local conditions in which these activities would be pursued. A potential mitigation action that would support the goal and objective goal example above is “Acquire repetitive flood loss properties in the Acadia Woods Subdivision.” In the 2017 LHMP, each jurisdiction was required to develop a Mitigation Strategy Proposal based on one of the following:
1. The strategy, goal, or objective rating “High Priority” on the Local Jurisdiction Mitigation Strategies and Goals (WORKSHEET ABOVE)
2. A specifically identified strategy, goal, or objective that was developed as part of one of the working groups planning sessions such as the hospitals or agriculture.
3. A specifically identified strategy, goal, or objective that was developed as part of one of the jurisdiction’s internal working group planning sessions
6. LOCAL JURISDICTION PROPOSED MITIGATION ACTION AND STRATEGY
PROPOSAL
a. Instructions for Updating Jurisdictions and Special Districts: With your planning team, please review the table from # 5, and determine if you’re ranking from the 2023 LHMP remains the same.
Review the chosen Mitigation Strategy that your jurisdiction submitted. The updated plan must identify the completed, deleted, or deferred actions or activities from the previously approved plan as a benchmark for progress.
If the mitigation actions or activities remain unchanged from the previously approved plan, the updated plan must indicate why changes are not necessary. Further, the updated plan shall include in its prioritization any new mitigation actions identified since the previous plan was approved or through the plan update process.
b. Instructions for New Jurisdictions and Special Districts: With your planning team, Use the “High Priority” rated strategy, goal or objective as a starting point to determine your Mitigation Strategy Proposal.
CITY OF CORONA 106
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LOCAL JURISDICTION PROPOSED MITIGATION ACTION AND STRATEGY PROPOSAL Jurisdiction: City of Corona
Contact: Lee Shin
Phone: 951-496-1299
MITIGATION STRATEGY INFORMATION
Proposal Name:
DWP Emergency Generators
Proposal Location:
Citywide – Ground Water Wells and Blending station
Proposal Type
Place an "X" by the type of mitigation strategy (one or more may apply) Flood and mud flow mitigation
Fire mitigation
Elevation or acquisition of repetitively damaged structures or structures in high hazard areas Mitigation Planning (i.e., update building codes, planning develop guidelines, etc.) Development and implementation of mitigation education programs Development or improvement of warning systems
Additional Hazard identification and analysis in support of the local hazard mitigation plan Drinking and/or irrigation water mitigation
X Earthquake mitigation
Agriculture - crop related mitigation
Agriculture - animal related mitigation
Flood inundation/Dam failure
Weather/Temperature event mitigation
DESCRIPTION OF THE PROPOSED MITIGATION STRATEGY
Proposal/Event
History
List any previous disaster related events (dates, costs, etc.) The proposed project is to purchase emergency generators for each ground water well and blending station as an earthquake mitigation strategy. The Mexico, Easter earthquake of 2010 caused significant damage to the water systems in Imperial County and the action is a result of lessons learned. There have been earthquakes in the region that have made it apparent that emergency generators will be necessary at ground water wells and blending stations to lessen the possibility of water disruption.
Description of
Mitigation Goal
Narrative:
Give a detailed description of the need for the proposal, any history related to the proposal. List the activities necessary for its completion in the narrative section below, including estimated timeline. (How long will it take)
Because the City of Corona is in an area of seismic faults, back-up power for pumping water at ground water wells to the community is a good mitigation measure. There have been earthquakes in the region that have made it apparent that emergency generators will be necessary at ground water wells and the blending station to lessen the possibility of water disruption.
CITY OF CORONA 107
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Does your jurisdiction have primary responsibility for the proposal? If not, what agency does? Yes X No Responsible Agency: Dept. of Water and Power
FUNDING INFORMATION
Place an "X" by the proposed source of funding for this proposal Unfunded proposal - funds are not available for the proposal currently Local jurisdiction General Fund
Local jurisdiction Special Fund (road tax, assessment fees, etc.) Non-FEMA Hazard Mitigation Funds
X Local Hazard Mitigation Grant Funds - Future Request
X Hazard Mitigation Funds
X Other no general fund source.
Has your jurisdiction evaluated this mitigation strategy to determine its cost benefits? yes
(i.e., has the cost of the mitigation proposal been determined to be beneficial in relationship to the potential damage or loss using the attached Cost/Benefit Analysis Sheet or another internal method)
As part of this process, each Submitting Jurisdiction is required to perform a cost-benefit analysis. They were required to answer the question at the bottom of the Proposal page that asks if they had conducted a CostBenefit Analysis of some type. This analysis was conducted either by completing a Cost Benefit form or by some other approved method. Many of the jurisdictions used the cost-effective analysis approach outlined in the FEMA publication, Cost and Benefits of Natural Hazards Mitigation. This cost-benefit analysis was not restricted to natural hazards.
In some cases, the jurisdiction or working group identified a proposal that highlighted a life- safety issue over a standard hazard proposal. This was done when there was either historical data or other sources of information indicating that the life-safety issue needed to be emphasized or brought to the public’s attention.
CITY OF CORONA 108
LOCAL HAZARD MITIGATION PLAN FEB 2023 LOCAL JURISDICTION DEVELOPMENT TRENDS QUESTIONNAIRE JURISDICTION: CITY OF CORONA DOES YOUR AGENCY HAVE RESPONSIBILITY FOR LAND USE AND/OR DEVELOPMENT ISSUES WITHIN YOUR JURISDICTIONAL BOUNDARIES? YES NO
2012 DATA 2017 DATA 2023
Current Population in Jurisdiction or Served 153,649 167,759 Projected Population in Jurisdiction or Served - in 2022 175,000
Current Sq. Miles in Jurisdiction or Served 39.2 39.2 Projected Sq. Miles in Jurisdiction or Served - in 2022 39.2 Does Your Jurisdiction have any ordinances or regulations dealing with disaster mitigation, disaster preparation, or disaster response? Yes Yes
If yes, please list ordinance or regulation number. Ordinance No. 2429, 1973, 2077 Corona Municipal Code Chapters 2.52, 3.36, 4.04.80, 7a, 15.12.270 Section 705 What is the number one land issue your agency will face in the next five years Economy and Infill/compact development
Approximate Number of Homes/Apts/etc. 47,182 48,930 Projected Number of Homes/Apts/etc.- in 2022 50,500
Approximate Total Residential Value $16.3 billion $17.0 billion Projected Residential Total Value - in 2022 $19.0 billion Approximate Number of Commercial Businesses 5,205 9,000 Projected Number of Commercial Businesses - in 2022 9,500 Approximate Percentage of Homes/Apts/etc. in flood hazard zones
0.7% 0.7% Approximate Percentage of Homes/Apts/etc. in flood hazard zones - in 2017
0.7%
Approximate Percentage of Homes/Apts/etc. in earthquake hazard zones
3.5% 3.5% Approximate Percentage of Homes/Apts/etc. in
earthquake hazard zones - in 2022
3.5%
Approximate Percentage of Homes/Apts/etc. in wildland fire hazard zones
6.55% 6.55% Approximate Percentage of Homes/Apts/etc. in wildland fire hazard zones - in 2022
6.55%
Approximate Percentage of Commercial Businesses in flood hazard zones
0.003% 0.7% Approximate Percentage of Commercial Businesses in flood hazard zones - in 2022
0.7%
Approximate Percentage of Commercial Businesses in earthquake hazard zones
1.9% 0.3% Approximate Percentage of Commercial Businesses in earthquake hazard zones - in 2022
0.3%
Approximate Percentage of Commercial Businesses in wildland fire hazard zones
4.5% 0 Approximate Percentage of Commercial Businesses in wildland fire hazard zones - in 2022
0 Number of Critical Facilities in your Jurisdiction that are in flood hazard zones 0 0 Projected Number of Critical Facilities in your Jurisdiction that are in flood hazard zones - in 2022
0 Number of Critical Facilities in your Jurisdiction that are in earthquake hazard zones 2 2 Number of Critical Facilities in your Jurisdiction that are in earthquake hazard zones - in 2022
2 Number of Critical Facilities in your Jurisdiction that are in wildland fire hazard zones. 7 7 Number of Critical Facilities in your Jurisdiction that are in wildland fire hazard zones - in 2022
7 Does your jurisdiction plan on participating in the County's on-going plan maintenance program every two years as described in Part I of the plan? Yes Yes If not, how will your jurisdiction do plan maintenance? N/A Will a copy of this plan be available for the various planning groups within your jurisdiction for use in future planning and budgeting purposes? Yes
CITY OF CORONA 109
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APPENDIX C – PLAN REVIEW TOOL/CROSSWALK
LOCAL MITIGATION PLAN REVIEW TOOL
The Local Mitigation Plan Review Tool demonstrates how the Local Mitigation Plan meets the regulation in 44 CFR §201.6 and offers States and FEMA Mitigation Planners an opportunity to provide feedback to the community.
• The Regulation Checklist provides a summary of FEMA’s evaluation of whether the Plan has addressed all requirements.
• The Plan Assessment identifies the plan’s strengths as well as documents areas for future improvement.
• The Multi-jurisdiction Summary Sheet is an optional worksheet that can be used to document how each jurisdiction met the requirements of each Element of the Plan (Planning Process; Hazard Identification and Risk Assessment; Mitigation Strategy; Plan Review, Evaluation, and Implementation; and Plan Adoption).
The FEMA Mitigation Planner must reference this Local Mitigation Plan Review Guide when completing the Local Mitigation Plan Review Tool.
Jurisdiction:
City of Corona
Title of Plan:
Local Hazard Mitigation Plan
Date of Plan:
2/1/2023
Local Point of Contact:
Lee Shin
Address:
735 Public Safety Way
Title: Corona, CA 92880
Emergency Services Manager
Agency:
Fire Department
Phone Number:
951-496-1299
E-Mail:
[email protected]
State Reviewer: Title: Date:
FEMA Reviewer: Title: Date:
Date Received in FEMA Region (insert
#)
Plan Not Approved
Plan Approvable Pending Adoption
Plan Approved
CITY OF CORONA 110
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SECTION 1:
REGULATION CHECKLIST
INSTRUCTIONS: The Regulation Checklist must be completed by FEMA. The purpose of the Checklist is to identify the location of relevant or applicable content in the Plan by Element/sub-element and to determine if each requirement has been ‘Met’ or ‘Not Met.’ The ‘Required Revisions’ summary at the bottom of each Element must be completed by FEMA to provide a clear explanation of the revisions that are required for plan approval. Required revisions must be explained for each plan sub-element that is ‘Not Met.’ Sub-elements should be referenced in each summary by using the appropriate numbers (A1, B3, etc.), where applicable. Requirements for each Element and sub-element are described in detail in this Plan Review Guide in Section 4, Regulation Checklist.
1. REGULATION CHECKLIST Location in
Plan
(Section and/or
page number) Met
Not
Regulation (44 CFR 201.6 Local Mitigation Plans) Met
ELEMENT A. PLANNING PROCESS
A1. Does the Plan document the planning process, including how it was prepared and who was involved in the process for each jurisdiction? (Requirement §201.6(c)(1))
Section 2.1
X
A2. Does the Plan document an opportunity for neighboring communities, local and regional agencies involved in hazard mitigation activities, agencies that have the authority to regulate development as well as other interests to be involved in the planning process? (Requirement §201.6(b)(2))
Section 2.2
X
A3. Does the Plan document how the public was involved in the planning process during the drafting stage? (Requirement §201.6(b)(1))
Section 2.3
X
A4. Does the Plan describe the review and incorporation of existing plans, studies, reports, and technical information? (Requirement §201.6(b)(3))
Section 9.0
X
A5. Is there discussion of how the community will continue public participation in the plan maintenance process? (Requirement §201.6(c)(4)(iii))
Section 10.0
Section 8.0 X
CITY OF CORONA 111
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1. REGULATION CHECKLIST Location in
Plan
(Section and/or
page number) Met
Not
Regulation (44 CFR 201.6 Local Mitigation Plans) Met
A6. Is there a description of the method and schedule for keeping the plan current (monitoring, evaluating, and updating the mitigation plan within a 5-year cycle)? (Requirement §201.6(c)(4)(I))
Section 8.0
X
ELEMENT A: REQUIRED REVISIONS
ELEMENT B. HAZARD IDENTIFICATION AND RISK ASSESSMENT
B1. Does the Plan include a description of the type, location, and extent of all natural hazards that can affect each jurisdiction(s)? (Requirement §201.6(c)(2)(I))
Section 3.4
B2. Does the Plan include information on previous occurrences of hazard events and on the probability of future hazard events for each jurisdiction? (Requirement §201.6(c)(2)(I))
Section 3.4
B3. Is there a description of each identified hazard’s impact on the community as well as an overall summary of the community’s vulnerability for each jurisdiction? (Requirement §201.6(c)(2)(ii)) Section 4.4
Section 3.2
B4. Does the Plan address NFIP insured structures within the jurisdiction that have been repetitively damaged by floods? (Requirement §201.6(c)(2)(ii))
Section 5.1
Figure 4.4.2 pg.42
ELEMENT B: REQUIRED REVISIONS
ELEMENT C. MITIGATION STRATEGY
C1. Does the plan document each jurisdiction’s existing authorities, policies, programs and resources and its ability to expand on and improve these existing policies and programs? (Requirement §201.6(c)(3))
Section 6.1
C2. Does the Plan address each jurisdiction’s participation in the NFIP and continued compliance with NFIP requirements, as appropriate? (Requirement §201.6(c)(3)(ii))
Section 5.2
C3. Does the Plan include goals to reduce/avoid long-term vulnerabilities to the identified hazards? (Requirement §201.6(c)(3)(i))
Section 7.1
C4. Does the Plan identify and analyze a comprehensive range of specific mitigation actions and projects for each jurisdiction being considered to reduce the effects of hazards, with emphasis on new and existing buildings and infrastructure? (Requirement §201.6(c)(3)(ii))
Section 7.2
Section 7.3
CITY OF CORONA 112
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1. REGULATION CHECKLIST Location in
Plan
(Section and/or
page number) Met
Not
Regulation (44 CFR 201.6 Local Mitigation Plans) Met
C5. Does the Plan contain an action plan that describes how the actions identified will be prioritized (including cost benefit review), implemented, and administered by each jurisdiction? (Requirement §201.6(c)(3)(iv)); (Requirement §201.6(c)(3)(iii))
Section 7.2
Section 7.4
C6. Does the Plan describe a process by which local
governments will integrate the requirements of the mitigation plan into other planning mechanisms, such as comprehensive or capital improvement plans, when appropriate?
(Requirement §201.6(c)(4)(ii))
Section 9.0
Section 7.3
ELEMENT C: REQUIRED REVISIONS
ELEMENT D. PLAN REVIEW, EVALUATION, AND IMPLEMENTATION (applicable to plan updates only)
D1. Was the plan revised to reflect changes in development? (Requirement §201.6(d)(3))
Section 1.4
Section 1.5
Section 1.6
D2. Was the plan revised to reflect progress in local mitigation efforts? (Requirement §201.6(d)(3))
Section 3.5
D3. Was the plan revised to reflect changes in priorities? (Requirement §201.6(d)(3))
Section 3.1
Section 3.2
Section 3.3
ELEMENT D: REQUIRED REVISIONS
ELEMENT E. PLAN ADOPTION
E1. Does the Plan include documentation that the plan has been formally adopted by the governing body of the jurisdiction requesting approval? (Requirement §201.6(c)(5))
Plan Adoption/
Resolution
E2. For multi-jurisdictional plans, has each jurisdiction requesting approval of the plan documented formal plan adoption?
(Requirement §201.6(c)(5))
Plan Adoption/
Resolution
ELEMENT E: REQUIRED REVISIONS
ELEMENT F. ADDITIONAL STATE REQUIREMENTS (OPTIONAL FOR STATE REVIEWERS ONLY; NOT TO BE COMPLETED BY FEMA)
F1.
F2.
ELEMENT F: REQUIRED REVISIONS
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SECTION 2:
PLAN ASSESSMENT
INSTRUCTIONS: The purpose of the Plan Assessment is to offer the local community more comprehensive feedback to the community on the quality and utility of the plan in a narrative format. The audience for the Plan Assessment is not only the plan developer/local community planner, but also elected officials, local departments and agencies, and others involved in implementing the Local Mitigation Plan. The Plan Assessment must be completed by FEMA. The Assessment is an opportunity for FEMA to provide feedback and information to the community on 1) suggested improvements to the Plan; 2) specific sections in the Plan where the community has gone above and beyond minimum requirements; 3) recommendations for plan implementation; and 4) ongoing partnership(s) and information on other FEMA programs, specifically Risk MAP and Hazard Mitigation Assistance programs.
The Plan Assessment is divided into two sections:
1. Plan Strengths and Opportunities for Improvement
2. Resources for Implementing Your Approved Plan
Plan Strengths and Opportunities for Improvement is organized according to the plan Elements listed in the Regulation Checklist. Each Element includes a series of italicized bulleted items that are suggested topics for consideration while evaluating plans, but it is not intended to be a comprehensive list. FEMA Mitigation Planners are not required to answer each bullet item and should use them as a guide to paraphrase their own written assessment (2-3 sentences) of each Element.
The Plan Assessment must not reiterate the required revisions from the Regulation Checklist or be regulatory in nature and should be open-ended and provide the community with suggestions for improvements or recommended revisions. The recommended revisions are suggestions for improvement and are not required to be made for the Plan to meet Federal regulatory requirements. The italicized text should be deleted once FEMA has added comments regarding strengths of the plan and potential improvements for future revisions. It is recommended that the Plan Assessment be a short synopsis of the overall strengths and weaknesses of the Plan (no longer than two pages), rather than a complete recap section by section.
Resources for Implementing Your Approved Plan provides a place for FEMA to offer information, data sources and general suggestions on the plan implementation and maintenance process. Information on other possible sources of assistance including, but not limited to, existing publications, grant funding or training opportunities, can be provided.
States may add state and local resources, if available.
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A. Plan Strengths and Opportunities for Improvement
This section provides a discussion of the strengths of the plan document and identifies areas where these could be improved beyond minimum requirements.
Element A: Planning Process
How does the Plan go above and beyond minimum requirements to document the planning process with respect to:
Involvement of stakeholders (elected officials/decision makers, plan implementers, business owners, academic institutions, utility companies, water/sanitation districts, etc.); Involvement of Planning, Emergency Management, Public Works Departments or other planning agencies (i.e., regional planning councils);
Diverse methods of participation (meetings, surveys, online, etc.); and Reflective of an open and inclusive public involvement process.
Element B: Hazard Identification and Risk Assessment
In addition to the requirements listed in the Regulation Checklist, 44 CFR 201.6 Local Mitigation Plans identifies additional elements that should be included as part of a plan’s risk assessment. The plan should describe vulnerability in terms of:
1) A general description of land uses and future development trends within the community so that mitigation options can be considered in future land use decisions. 2) The types and numbers of existing and future buildings, infrastructure, and critical facilities located in the identified hazard areas; and
3) A description of potential dollar losses to vulnerable structures, and a description of the methodology used to prepare the estimate.
How does the Plan go above and beyond minimum requirements to document the Hazard Identification and Risk Assessment with respect to:
Use of best available data (flood maps, HAZUS, flood studies) to describe significant hazards.
Communication of risk on people, property, and infrastructure to the public (through tables, charts, maps, photos, etc.).
Incorporation of techniques and methodologies to estimate dollar losses to vulnerable structures.
Incorporation of Risk MAP products (i.e., depth grids, Flood Risk Report, Changes Since Last FIRM, Areas of Mitigation Interest, etc.); and
Identification of any data gaps that can be filled as new data became available.
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Element C: Mitigation Strategy
How does the Plan go above and beyond minimum requirements to document the Mitigation Strategy with respect to:
Key problems identified in, and linkages to, the vulnerability assessment. Serving as a blueprint for reducing potential losses identified in the Hazard Identification and Risk Assessment.
Plan content flow from the risk assessment (problem identification) to goal setting to mitigation action development.
An understanding of mitigation principles (diversity of actions that include structural projects, preventative measures, outreach activities, property protection measures, postdisaster actions, etc.). Specific mitigation actions for each participating jurisdictions that reflects their unique risks and capabilities.
Integration of mitigation actions with existing local authorities, policies, programs, and resources; and
Discussion of existing programs (including the NFIP), plans, and policies that could be used to implement mitigation, as well as document past projects.
Element D: Plan Update, Evaluation, and Implementation (Plan Updates Only) How does the Plan go above and beyond minimum requirements to document the 5-year Evaluation and Implementation measures with respect to:
Status of previously recommended mitigation actions.
Identification of barriers or obstacles to successful implementation or completion of mitigation actions, along with possible solutions for overcoming risk. Documentation of annual reviews and committee involvement. Identification of a lead person to take ownership of, and champion the Plan. Reducing risks from natural hazards and serving as a guide for decisions makers as they commit resources to reducing the effects of natural hazards. An approach to evaluating future conditions (i.e., socio-economic, environmental, demographic, change in built environment etc.).
Discussion of how changing conditions and opportunities could impact community resilience in the long term; and
Discussion of how the mitigation goals and actions support the long-term community vision for increased resilience.
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B. Resources for Implementing Your Approved Plan
Ideas may be offered on moving the mitigation plan forward and continuing the relationship with key mitigation stakeholders such as the following:
What FEMA assistance (funding) programs are available (for example, Hazard Mitigation Assistance (HMA)) to the jurisdiction(s) to assist with implementing the mitigation actions?
What other Federal programs (National Flood Insurance Program (NFIP), Community Rating System (CRS), Risk MAP, etc.) may aid with mitigation activities? What publications, technical guidance or other resources are available to the jurisdiction(s) relevant to the identified mitigation actions? Are there upcoming trainings/workshops (Benefit-Cost Analysis (BCA), HMA, etc.) to assist the jurisdictions(s)?
What mitigation actions can be funded by other Federal agencies (for example, U.S.
Forest Service, National Oceanic and Atmospheric Administration (NOAA), Environmental Protection Agency (EPA) Smart Growth, Housing and Urban Development (HUD) Sustainable Communities, etc.) and/or state and local agencies? CITY OF CORONA 117
LOCAL HAZARD MITIGATION PLAN JUNE 2017 SECTION 3: MULTI-JURISDICTION SUMMARY SHEET (OPTIONAL) CITY OF CORONA 118
LOCAL HAZARD MITIGATION PLAN FEB 2023 INSTRUCTIONS: For multi-jurisdictional plans, a Multi-jurisdiction Summary Spreadsheet may be completed by listing each participating jurisdiction, which required Elements for each jurisdiction were ‘Met’ or ‘Not Met,’ and when the adoption resolutions were received. This Summary Sheet does not imply that a mini plan be developed for each jurisdiction; it should be used as an optional CITY OF CORONA 119
LOCAL HAZARD MITIGATION PLAN FEB 2023 worksheet to ensure that each jurisdiction participating in the Plan has been documented and has met the requirements for thoseElements (A through E).
CITY OF CORONA 120
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MULTI-JURISDICTION SUMMARY SHEET
# Jurisdiction Name
Jurisdiction
Type
(city/borough
/
township/
village, etc.)
Plan
POC
Mailing
Address Email Phone
Requirements Met (Y/N)
A.
Planning
Process
B.
Hazard
Identification
& Risk
Assessment
C.
Mitigatio
n
Strategy
D.
Plan Review,
Evaluation &
Implementatio
n
E.
Plan
Adoptio
n
F.
State
Require
-ments
1 2 3 4 5 6 7 8 9
10 11 12 13 14 15
CITY OF CORONA 121
LOCAL HAZARD MITIGATION PLAN FEB 2023
MULTI-JURISDICTION SUMMARY SHEET
# Jurisdiction Name
Jurisdiction
Type
(city/borough
/
township/
village, etc.)
Plan
POC
Mailing
Address Email Phone
Requirements Met (Y/N)
A.
Planning
Process
B.
Hazard
Identification
& Risk
Assessment
C.
Mitigatio
n
Strategy
D.
Plan Review,
Evaluation &
Implementatio
n
E.
Plan
Adoptio
n
F.
State
Require
-ments
16 17 18 19 20
Appendices
City of Corona
2025 Urban Water Management Plan
Appendix Q – Bed-Coldwater Groundwater Sustainability Plan
GROUNDWATER SUSTAINABILITY PLAN
BEDFORD-COLDWATER BASIN
| NOVEMBER 2021 |
GROUNDWATER
SUSTAINABILITY PLAN
BEDFORD-COLDWATER BASIN
November 2021
Bedford-Coldwater GSP i
TODD GROUNDWATER,
H&H Water Resources,
and Stantec
Table of Contents
Executive Summary.............................................................................................................. ES-1
1. Introduction................................................................................................................... 1-1
1.1. Purpose of the Groundwater Sustainability Plan ................................................... 1-1
1.2. Sustainability Goal ................................................................................................. 1-3
1.3. Agency Information ............................................................................................... 1-4
1.3.1. Organization and Management Structure..................................................... 1-4
1.3.2. Legal Authority............................................................................................... 1-5
1.3.3. GSP Implementation Cost Estimate and Schedule ........................................ 1-5
1.4. GSP Organization ................................................................................................... 1-6
2. Plan Area........................................................................................................................ 2-1
2.1. Description of the Plan Area .................................................................................. 2-1
2.1.1. Geographic Area ............................................................................................ 2-1
2.1.2. Jurisdictional Agencies................................................................................... 2-1
2.1.3. Disadvantaged Communities......................................................................... 2-2
2.1.4. Water Supply Sources.................................................................................... 2-3
2.1.5. Water Use Sectors.......................................................................................... 2-4
2.1.6. Water Resources Monitoring and Management Programs........................... 2-5
2.1.7. General Plans, Land Use Planning, and Well Permitting ............................. 2-10
2.1.8. Notice and Communication ......................................................................... 2-12
3. Hydrogeologic Conceptual Model ................................................................................. 3-1
3.1. Physical Setting and Topography........................................................................... 3-1
3.2. Surface Water Features......................................................................................... 3-1
3.3. Soils........................................................................................................................ 3-2
3.4. Geologic Setting ..................................................................................................... 3-2
3.5. Faults...................................................................................................................... 3-3
3.6. Principal Aquifer..................................................................................................... 3-4
3.6.1. Description of Principal Aquifer..................................................................... 3-4
3.6.2. Description of Lateral Boundaries ................................................................. 3-4
3.7. Definable Basin Bottom ......................................................................................... 3-4
3.8. Cross Sections........................................................................................................ 3-5 Bedford-Coldwater GSP ii
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3.9. Structures Affecting Groundwater......................................................................... 3-5
3.10. Recharge and Discharge Areas........................................................................... 3-5
3.11. Primary Groundwater Uses................................................................................ 3-6
3.11.1. Bedford Area.................................................................................................. 3-6
3.11.2. Coldwater Area .............................................................................................. 3-7
3.12. Data Gaps in the Hydrogeologic Conceptual Model.......................................... 3-7
4. Current and Historical Groundwater Conditions........................................................... 4-1
4.1. Groundwater Elevations........................................................................................ 4-1
4.1.1. Available Data ................................................................................................ 4-1
4.1.2. Groundwater Occurrence .............................................................................. 4-1
4.1.3. Groundwater Elevations and Trends............................................................. 4-1
4.1.4. Groundwater Flow ......................................................................................... 4-2
4.1.5. Vertical Groundwater Gradients.................................................................... 4-3
4.2. Changes In Groundwater Storage.......................................................................... 4-3
4.3. Land Subsidence and Potential for Subsidence..................................................... 4-3
4.3.1. Interferometric Synthetic Aperture Radar (InSAR)........................................ 4-5
4.4. Groundwater Quality ............................................................................................. 4-5
4.4.1. Monitoring Networks..................................................................................... 4-6
4.5. Other Studies......................................................................................................... 4-7
4.5.1. Salt and Nutrient Management Plan 2017 .................................................... 4-7
4.6. Threats to Water Quality ....................................................................................... 4-7
4.6.1. Regulated Facilities........................................................................................ 4-7
4.6.2. Septic Systems ............................................................................................... 4-7
4.6.3. Non-point Sources ......................................................................................... 4-8
4.7. Key Constituents of Concern.................................................................................. 4-8
4.7.1. Key Constituents in Groundwater.................................................................. 4-8
4.7.2. Total Dissolved Solids (TDS)........................................................................... 4-8
4.7.3. Nitrate as Nitrogen (NO3 as N)....................................................................... 4-9
4.7.4. Other Constituents......................................................................................... 4-9
4.7.5. Vertical Variations in Water Quality ............................................................ 4-10
4.8. Seawater Intrusion Conditions............................................................................. 4-10
4.9. Interconnection of Surface Water and Groundwater.......................................... 4-10
4.9.1. Stream Flow Measurements........................................................................ 4-10 Bedford-Coldwater GSP iii
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4.9.2. Depth to Groundwater................................................................................. 4-11
4.9.3. Riparian Vegetation ..................................................................................... 4-13
4.9.4. Wetlands...................................................................................................... 4-15
5. Water Budget................................................................................................................. 5-1
5.1. Water Budget Methodology .................................................................................. 5-1
5.2. Dry and Wet Periods.............................................................................................. 5-1
5.3. Water Balance Analysis Periods............................................................................. 5-2
5.4. Management Areas................................................................................................ 5-3
5.4.1. Bedford Management Area ........................................................................... 5-3
5.4.2. Coldwater Management Area........................................................................ 5-3
5.5. Methods of Analysis............................................................................................... 5-3
5.5.1. Rainfall-Runoff-Recharge Model.................................................................... 5-4
5.5.2. Groundwater Model ...................................................................................... 5-4
5.5.3. Simulation of Future Conditions.................................................................... 5-6
5.6. Surface Water Balance......................................................................................... 5-10
5.6.1. Inflows to Surface Water ............................................................................. 5-12
5.6.2. Outflows of Surface Water .......................................................................... 5-12
5.7. Groundwater Balance .......................................................................................... 5-13
5.7.1. Inflows to Groundwater............................................................................... 5-16
5.7.2. Outflows from Groundwater ....................................................................... 5-18
5.8. Change in Groundwater Storage ......................................................................... 5-19
5.9. Estimate of Sustainable Yield............................................................................... 5-20
6. Sustainable Management Criteria................................................................................. 6-1
6.1. Sustainability Goal ................................................................................................. 6-2
6.1.1. Description of Sustainability Goal.................................................................. 6-2
6.1.2. Approach to Sustainability Indicators............................................................ 6-2
6.1.3. Summary of Sustainable Management Criteria............................................. 6-3
6.2. Chronic Lowering of Groundwater Levels.............................................................. 6-4
6.2.1. Description of Undesirable Results................................................................ 6-5
6.2.2. Potential Causes of Undesirable Results........................................................ 6-6
6.2.3. Definition of Undesirable Results .................................................................. 6-6
6.2.4. Potential Effects on Beneficial Uses and Users.............................................. 6-7
6.2.5. Sustainable Management Criteria for Groundwater Levels.......................... 6-7 Bedford-Coldwater GSP iv
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6.2.6. Minimum Thresholds..................................................................................... 6-9
6.2.7. Measurable Objectives ................................................................................ 6-12
6.3. Reduction of Groundwater Storage..................................................................... 6-13
6.3.1. Description of Undesirable Results.............................................................. 6-13
6.3.2. Potential Causes of Undesirable Results...................................................... 6-14
6.3.3. Definition of Undesirable Results ................................................................ 6-14
6.3.4. Potential Effects on Beneficial Uses and Users............................................ 6-14
6.3.5. Sustainable Management Criteria for Groundwater Storage...................... 6-14
6.3.6. Minimum Threshold..................................................................................... 6-16
6.3.7. Measurable Objectives ................................................................................ 6-18
6.4. Seawater Intrusion............................................................................................... 6-19
6.5. Land Subsidence .................................................................................................. 6-19
6.5.1. Description of Undesirable Results.............................................................. 6-19
6.5.2. Potential Causes of Undesirable Results...................................................... 6-20
6.5.3. Potential Effects on Beneficial Uses and Users............................................ 6-21
6.5.4. Minimum Threshold..................................................................................... 6-21
6.5.5. Measurable Objectives ................................................................................ 6-23
6.6. Degradation of Water Quality.............................................................................. 6-23
6.6.1. Potential Causes of Undesirable Results...................................................... 6-24
6.6.2. Description of Undesirable Results.............................................................. 6-25
6.6.3. Potential Effects on Beneficial Uses and Users............................................ 6-25
6.6.4. Sustainable Management Criteria for Groundwater Quality ...................... 6-25
6.6.5. Minimum Thresholds................................................................................... 6-26
6.6.6. Measurable Objectives ................................................................................ 6-29
6.7. Depletions of Interconnected Surface Water...................................................... 6-29
6.7.1. Description of Undesirable Results.............................................................. 6-30
6.7.2. Potential Causes of Undesirable Results...................................................... 6-30
6.7.3. Definition of Undesirable Results ................................................................ 6-35
6.7.4. Potential Effects on Beneficial Uses and Users............................................ 6-35
6.7.5. Sustainable Management Criteria for Interconnected Surface Water........ 6-36
6.7.6. Minimum Threshold..................................................................................... 6-36
6.7.7. Measurable Objective.................................................................................. 6-39
6.7.8. Data Gaps..................................................................................................... 6-39 Bedford-Coldwater GSP v
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7. Monitoring Network ...................................................................................................... 7-1
7.1. Description of Monitoring Network....................................................................... 7-1
7.1.1. Chronic Lowering of Groundwater Levels...................................................... 7-3
7.1.2. Reduction of Groundwater in Storage........................................................... 7-4
7.1.3. Seawater Intrusion......................................................................................... 7-5
7.1.4. Subsidence ..................................................................................................... 7-5
7.1.5. Degraded Water Quality ................................................................................ 7-5
7.1.6. Depletion of Interconnected Surface Water.................................................. 7-6
7.2. Protocols for Data Collection and Monitoring....................................................... 7-7
7.2.1. Field Methods for Monitoring Well Data....................................................... 7-8
7.2.2. Field Methods for Groundwater Elevation Monitoring................................. 7-8
7.2.3. Field Methods for Groundwater Quality Monitoring .................................... 7-9
7.3. Representative Monitoring.................................................................................. 7-10
7.4. Data Management System (DMS) ........................................................................ 7-12
7.5. Assessment and Improvement of Monitoring Network...................................... 7-12
7.5.1. Identification and Description of Data Gaps................................................ 7-12
7.5.2. Description of Steps to Fill Data Gaps.......................................................... 7-13
8. Projects and Management Actions................................................................................ 8-1
8.1. Action 1 – Provide for Collection, Compilation, and Storage of Information Required for Annual Reports and Submit Annual Reports................................................................ 8-1
8.2. Action 2 – Routinely Record Groundwater Levels and Take Action if Necessary.. 8-3
8.3. Action 3 – Monitor Selected Groundwater Quality Constituents and Coordinate with the Regional Water Quality Control Board as Appropriate ............................................... 8-3
8.4. Action 4 – Track Trends in Groundwater Levels near Temescal Wash and Take Action as Necessary....................................................................................................................... 8-4
8.5. Action 5 – Review InSAR Data on the DWR Dataviewer Annually and Compile During 5-Year Updates .................................................................................................................. 8-4
8.6. Project 1 – Investigate Groundwater/Surface Water Interaction at Temescal Wash 8-4
8.7. Project 2 – Initiate a Survey of Active Private Wells.............................................. 8-5
8.8. Project 3 – Evaluation of the Effects of Aggregate Pits on Groundwater Flow and Quality8-6
9. Plan Implementation ..................................................................................................... 9-1
9.1. Plan Implementation Resources and Responsibilities........................................... 9-1
9.2. Plan Implementation Costs.................................................................................... 9-2 Bedford-Coldwater GSP vi
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9.2.1. Operating Expenses ....................................................................................... 9-2
9.2.2. GSP Implementation Costs ............................................................................ 9-3
9.2.3. Funding Methods for Operating Expenses and GSP Implementation Costs.. 9-3
9.3. Annual Reporting ................................................................................................... 9-4
9.4. New Information and Changes.............................................................................. 9-4
9.5. Periodic Evaluations............................................................................................... 9-4
9.6. Schedule For Implementation ............................................................................... 9-5
10. References................................................................................................................... 10-7 List of Tables
Table 1-1. GSP Preparation Checklist..................................................................................... 1-7 Table 5-1. Water Year Type Classification (Lake Elsinore station)......................................... 5-2 Table 5-2. Bedford-Coldwater Basin Land Use in 1990, 2018 and 2068 (acres).................... 5-9 Table 5-3. Average Annual Surface Water Budgets............................................................. 5-11 Table 5-4. Average Annual Groundwater Budgets.............................................................. 5-15 Table 5-5. Estimated Sustainable Yield................................................................................ 5-20 Table 6-1. Minimum Thresholds for Groundwater Levels..................................................... 6-8 Table 6-2. Bedford-Coldwater Water Quality Monitoring Wells......................................... 6-25 Table 6-3. Summary of Recent Average Total Dissolved Solids (TDS) and Nitrate Concentrations by Management Area................................................................................. 6-27 Table 7-1. Bedford Coldwater Monitoring Network Summary ............................................. 7-2 Table 7-2. Wells in the Bedford-Coldwater Groundwater Sustainability Agency Monitoring Network ............................................................................................................................... 7-11 Table 7-3. Identification and Description of Data Gaps....................................................... 7-13 Table 8-1. Action 1 – Provide for Collection, Compilation, and Storage of Information Required for Annual Reports and Submit Annual Reports.................................................... 8-8 Table 8-2. Action 2 – Routinely Record Groundwater Levels and Take Action if Necessary . 8-9 Table 8-3. Action 3 – Monitor Selected Groundwater Quality Constituents and Coordinate with the Regional Water Quality Control Board as Appropriate......................................... 8-10 Table 8-4. Action 4 – Track Trends in Groundwater Levels near Temescal Wash and Take Action as Necessary ............................................................................................................. 8-11 Table 8-5. Action 5 – Review InSAR Data on the SGMA Dataviewer During Updates......... 8-12 Table 8-6. Project 1 – Investigate Groundwater/Surface Water Interaction at Temescal Wash ..................................................................................................................................... 8-13 Bedford-Coldwater GSP vii
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Table 8-7. Project 2 – Initiate a Survey of Private Wells...................................................... 8-14 Table 8-8. Project 3 – Evaluation of the Effects of Aggregate Pits on Groundwater Flow and Quality.................................................................................................................................. 8-15 Table 9-1. Example GSP Implementation Responsibilities .................................................... 9-2 Table 9-2. GSP Implementation Cost Estimates .................................................................... 9-3 List of Figures
Figure ES-1. Bedford-Coldwater Basin................................................................................. ES-2 Figure ES-2. Bedford-Coldwater Basin Management Areas................................................ ES-3 Figure ES-3. Cumulative Storage Change: Bedford Management Area............................... ES-5 Figure ES-4. Cumulative Storage Change: Coldwater Management Area........................... ES-6 Figure 1-1. Bedford-Coldwater Groundwater Basin and GSA, and Adjacent Basins............. 1-2 Figure 1-2. SGMA Undesirable Results.................................................................................. 1-3 Figure 1-3. BCGSA Management Structure............................................................................ 1-5 Figure 2-1. Jurisdictional Boundaries, Bedford-Coldwater Basin ........................................ 2-14 Figure 2-2. Water Purveyor Boundaries, Bedford-Coldwater Basin.................................... 2-15 Figure 2-3. Estimated Density of All Wells........................................................................... 2-16 Figure 2-4. Estimated Density of Domestic Wells................................................................ 2-17 Figure 2-5. Estimated Density of Production Wells............................................................. 2-18 Figure 2-6. Estimated Density of Public Wells..................................................................... 2-19 Figure 2-7. Water Infrastructure.......................................................................................... 2-20 Figure 2-8. Land Use 2014 ................................................................................................... 2-21 Figure 2-9. General Plan Land Use Designations................................................................. 2-22 Figure 3-1. Basin Topography ................................................................................................ 3-8 Figure 3-2. Surface Water Bodies Tributary to Basin............................................................. 3-9 Figure 3-3. Subwatersheds Tributary to Basin..................................................................... 3-10 Figure 3-4. Basin Soil Hydrologic Properties........................................................................ 3-11 Figure 3-5. Surficial Geology ................................................................................................ 3-12 Figure 3-6. Depth to Bedrock............................................................................................... 3-13 Figure 3-7. Cross Section Line Orientations......................................................................... 3-14 Figure 3-8. Cross Section A to A’.......................................................................................... 3-15 Figure 3-9. Cross Section B to B’ .......................................................................................... 3-16 Figure 3-10. Groundwater Recharge and Discharge............................................................ 3-17 Bedford-Coldwater GSP viii
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Figure 4-1. Historically Monitored Wells............................................................................. 4-17 Figure 4-2. Representative Hydrographs Flagler Wells 2 and 2A ........................................ 4-18 Figure 4-3. Representative Hydrographs Non-Potable Well 1............................................. 4-19 Figure 4-4. Representative Hydrographs TVWD Well 4....................................................... 4-20 Figure 4-5. Representative Hydrographs New Sump........................................................... 4-21 Figure 4-6. Representative Hydrographs Corona Well 3 ..................................................... 4-22 Figure 4-7. Groundwater Elevation Contours, Fall 2015 ..................................................... 4-23 Figure 4-8. Groundwater Elevation Contours, Spring 2018................................................. 4-24 Figure 4-9. Concepts of Land Subsidence ............................................................................ 4-25 Figure 4-10. Basin-Wide Subsidence Estimates from Satellite Measurements................... 4-26 Figure 4-11. Wells with Water Quality Monitoring Data..................................................... 4-27 Figure 4-12. Total Dissolved Solids Concentrations in Wells 2011 through 2019 ............... 4-28 Figure 4-13. Nitrate as Nitrogen Concentrations in Wells................................................... 4-29 Figure 4-14. Local Watersheds and Gauging Stations ......................................................... 4-30 Figure 4-15. Local Streamflow 2013 through 2020 ............................................................. 4-31 Figure 4-16. Water Level Monitoring Wells and Riparian Vegetation................................. 4-32 Figure 4-17. Hydrographs for Wells with Shallow Depth to Water..................................... 4-33 Figure 4-18. Recent Riparian Vegetation Aerial Imagery..................................................... 4-34 Figure 4-19. TVWD Wastewater Treatment Plant Discharges, 2011 to 2018 ..................... 4-35 Figure 4-20. Aerial Photograph of Part of Temescal Wash in 1967..................................... 4-36 Figure 4-21. Wetlands in Basin ............................................................................................ 4-37 Figure 4-22. Coastal California Gnatcatcher Critical Habitat Area....................................... 4-38 Figure 5-1. Cumulative Departure of Annual Precipitation ................................................. 5-23 Figure 5-2. Management Areas ........................................................................................... 5-24 Figure 5-3. Effect of Climate Change on Precipitation and Evapotranspiration.................. 5-25 Figure 5-4. Land Use in 2068................................................................................................ 5-26 Figure 5-5. Surface Water Budgets 1990 through 2018 ...................................................... 5-27 Figure 5-6. Annual Groundwater Budgets, 1990 to 2018.................................................... 5-28 Figure 5-7. Annual Groundwater Budgets, Baseline............................................................ 5-29 Figure 5-8. Annual Groundwater Budgets, Growth Plus Climate Change ........................... 5-30 Figure 5-9. Average Annual Dispersed Recharge 1993 through 2007................................. 5-31 Figure 5-10. Cumulative Storage Changes 1990 to 2068..................................................... 5-32 Figure 6-1. Water Level Key Wells....................................................................................... 6-41 Bedford-Coldwater GSP ix
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Figure 6-2. Aerial Images of Riparian Vegetation 1994-2018.............................................. 6-42 Figure 6-3. Annual Groundwater Pumping Near Temescal Wash ....................................... 6-43 Figure 6-4. Water Levels in Wells Near Temescal Wash...................................................... 6-44 Figure 6-5. Wastewater Discharges to Temescal Wash 1989-2019 .................................... 6-45 Figure 7-1. Groundwater Level Wells, Dedicated and Other Monitoring Wells.................. 7-14 Figure 7-2. Water Quality Monitoring Wells........................................................................ 7-15 Figure 9-1. Schedule for GSP Implementation....................................................................... 9-6 Appendices (following text)
Appendix A – Joint Powers Agreement forming the Bedford-Coldwater Groundwater Sustainability Agency
Appendix B – Bedford-Coldwater GSA Notice of Decision to become a Groundwater Sustainability Agency
Appendix C – GSP Elements Guide
Appendix D – BCGSA Stakeholder Outreach Plan
Appendix E – Public Meeting Summaries
Appendix F – Draft GSP Comments and Responses
Appendix G – Bedford-Coldwater GSP Numerical Groundwater Model Documentation Report
Appendix H – Baseline Water Quality Sampling Results
Appendix I – Management Areas Designated in the Bedford Coldwater Subbasin to be Included in the Groundwater Sustainability Plan
Appendix J – Detailed Annual Surface and Groundwater Budgets Appendix K – Bedford-Coldwater GSP Data Management System Description Acronyms
Actions Management Actions
AF acre-feet
AFY acre-foot per year
Agreement Joint Powers Agreement forming the BCGSA
Basin Plan Water Quality Control Plan for the Santa Ana River Basin Basin Bedford-Coldwater Subbasin
BCGSA Bedford-Coldwater Groundwater Sustainability Agency bgs below ground surface
Board BCGSA Board of Directors
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CASGEM California Statewide Groundwater Elevation Monitoring CCED California Conservation Easement Database
CCR California Code of Regulations
CDFW California Department of Fish and Wildlife
cfs cubic feet per second
CIMIS California Irrigation Management Information System COC constituent of concern
Corona City of Corona
DDW Division of Drinking Water
DMS Data Management System
DPR Department of Pesticide Regulation
DWR California Department of Water Resources
DWSAP Drinking Water Source Water Assessment Program
EMWD Eastern Municipal Water District
ET evapotranspiration
ET0 reference evapotranspiration
EVMWD Elsinore Valley Municipal Water District
FMMP Farmland Mapping and Monitoring Program
ft feet
GAMA Groundwater Ambient Monitoring and Assessment
GDE groundwater dependent ecosystem
GIS geographic information system
GMZs groundwater management zones
GPS Global Positioning System
GSA Groundwater Sustainability Agency
GSP Groundwater Sustainability Plan
GWMP Groundwater Management Plan
in/yr inches per year
InSAR Interferometric Synthetic Aperture Radar
IRWMP Integrated Regional Water Management Plan
JPA Joint Powers Authority
km2 square kilometers
M&I municipal, commercial, and industrial
MA Management Area
MCL Maximum Contaminant Level
Metropolitan Metropolitan Water District of Southern California mg/L milligrams per liter
mi2 square miles
MO Measurable Objective
MODFLOW United States Geological Survey modular finite-difference flow model MSHCP Western Riverside County Multiple Species Habitat Conservation Plan msl mean sea level
MT Minimum Threshold
NAD83 North American Datum of 1983
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NAVD88 North American Vertical Datum of 1988
NCCAG Natural Communities Commonly Associated with Groundwater NCED National Conservation Easement Database
NDMI normalized difference moisture index
NDVI normalized difference vegetation index
NED National Elevation Dataset
ng/L nanograms per liter
NO3 nitrate
NOAA National Oceanic and Atmospheric Administration
NPS nonpoint source
NRCS US Department of Agriculture, Natural Resources Conservation Service
NTU nephelometric turbidity unit
NWIS National Water Information System
ORP oxidation-reduction potential
OWTS on-site wastewater treatment system
PFOA perfluorooctanoic acid
PFOS perfluorooctanesulfonic acid
ppt parts per trillion
Projects projects to support sustainability
QA/QC quality assurance and quality control
RCRCD Riverside County Resource Conservation District
RFP Request for Proposal
RWQCB Santa Ana Regional Water Quality Control Board
SARHCP Upper Santa Ana River Habitat Conservation Plan
SCADA Supervisory Control and Data Acquisition
SFR Streamflow Routing Package
SGMA Sustainable Groundwater Management Act
SMC Sustainable Management Criteria
SMCL Secondary Maximum Contaminant Level
SMP Surface Mining Permit
SNMP Salt and Nutrient Management Plan
SSURGO Soil Survey Geographic Database
SWP State Water Project
SWRCB State Water Resources Control Board
TDS Total Dissolved Solids
TNC The Nature Conservancy
TVWD Temescal Valley Water District
USDA United States Department of Agriculture
USGS United States Geological Survey
UTV Upper Temescal Valley
UWMP Urban Water Management Plan
WMWD Western Municipal Water District
WRF Water Reclamation Facility
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EXECUTIVE SUMMARY
The Sustainable Groundwater Management Act (SGMA) requires local agencies in groundwater basins designated as high- or medium-priority to form Groundwater Sustainability Agencies (GSAs) and develop a Groundwater Sustainability Plan (GSP) to plan for achieving and/or maintaining sustainability within 20 years of implementing the plan. The Bedford-Coldwater Groundwater Subbasin (Basin) has been designated by the California Department of Water Resources (DWR) as very low-priority, so the preparation of a GSP is not required. However, the City of Corona (Corona), Temescal Valley Water District (TVWD), and Elsinore Valley Municipal Water District (EVMWD), the three major water purveyors and groundwater users in the Basin, are committed to protecting and maintaining sustainable groundwater conditions in the Basin into the future.
The three agencies signed a Joint Powers Agreement (Agreement) creating a Joint Powers Authority (JPA) and forming the Bedford-Coldwater Groundwater Sustainability Agency (BCGSA). The BCGSA has volunteered to become the GSA for the Bain and prepare and implement this GSP.
BASIN SETTING
Figure ES-1 shows the Basin located in western Riverside County. Figure ES-1 also shows the adjacent Temescal Basin to the northwest and Elsinore Valley Subbasin to the south. The Basin is bound on the east and west by consolidated rocks of Estelle Mountain and the Santa Ana Mountains, respectively.
The Bedford-Coldwater Basin is composed of alluvial fan, alluvial valley, axial channel, and wash deposits. These deposits are sourced from the Santa Ana Mountains to the west of the Basin and the Peninsular Ranges to the east of the Basin. The alluvial fan deposits in the Coldwater area extend into the Bedford area and have been disrupted by faulting. Channel deposits along Temescal Wash and local tributaries define the eastern boundary of the Basin.
In the northern Bedford area, a variety of Tertiary sedimentary units crop out and the character of these deposits and the groundwater chemistry differs from the alluvial fans to the north in the Temescal Subbasin and those to the south in the Elsinore Groundwater Basin.
These deposits vary in depth from less than 40 feet up to 500 feet in the Bedford area (eastern portion of the Basin) and up to 800 feet in thickness in the deepest portions of the Coldwater area (western portion of the Basin).
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Figure ES-1. Bedford-Coldwater Basin
The Basin is divided into two Management Areas (MAs) designed to facilitate analysis, management, and implementation of the GSP. The MAs are shown on Figure ES-2. The Bedford MA occupies roughly the eastern two-thirds of the Basin. It is separated from the Coldwater MA by the Glen Ivy Fault, which is a partial barrier to groundwater flow. The Coldwater MA is the part of the Basin west of the Glen Ivy Fault. Because of downward movement on that side of the fault, Basin thickness is much greater than in the Bedford MA.
The partner agencies of the BCGSA are the primary groundwater users in the basin. There are no disadvantaged communities (DACs) or tribal lands in the Basin, and the BCGSA believes there are very few private wells, none of which are used for potable water supply in the Basin.
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Figure ES-2. Bedford-Coldwater Basin Management Areas
GROUNDWATER CONDITIONS
Basin groundwater elevations have been relatively stable in recent years. Groundwater elevations in the northern portion of the Bedford MA show a slight decrease during the 2013 through 2015 drought but have begun to recover. Groundwater elevations in the Coldwater MA declined over the last 24 years with significant fluctuations in response to wet and dry cycles. Water levels in the Coldwater area have varied more than 350 feet during this period and there have been multiple major and minor cycles of groundwater elevation decline and recovery. The wide water level fluctuations over time in the Coldwater area likely reflect the relatively small footprint and fault-controlled flow along with the fact that most of the pumping in the Basin occurs in this area. Although long-term declines in groundwater elevations have occurred in Coldwater in the past, recent groundwater elevations have stabilized due in part to shared management of the Basin between the BCGSA agencies.
Total Dissolved Solids (TDS) and nitrate are the primary constituents of concern in the Basin.
TDS concentrations are relatively low in the Coldwater MA, naturally higher in Bedford MA, and generally increase downstream. Groundwater in the Basin has been impacted by human activities in the Basin and watershed including agricultural, urban, and industrial land uses.
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Nitrate has historically been the most significant constituent of concern in the Basin. Water quality in the Basin is generally within drinking water standards.
WATER SUPPLY
Sources of water supply for agricultural, Municipal and Industrial (M&I), and domestic uses include groundwater, imported water, and recycled water. Metropolitan Water District of Southern California (Metropolitan) is the wholesaler for imported water and its sources of water include the Colorado River and the State Water Project. Both Corona and TVWD receive imported water from Metropolitan for distribution in the Basin. EVMWD also receives imported water from Metropolitan through Western Municipal Water District (WMWD), but only distributes imported water within the Basin when groundwater supply to customers is insufficient.
Groundwater has been an important component of water supply in the Basin for more than 100 years. Until the 1970s, most of the groundwater production in the Basin was for agricultural supply. A few well owners have also produced small amounts of groundwater for domestic use. Production for municipal supply increased in the 1960s and 1970s and continues today.
For more than 50 years, Corona, EVMWD, and TVWD have relied on groundwater from the Basin for municipal uses, and these agencies have long been responsible for managing groundwater conditions in the Basin. Corona and EVMWD have legal agreements for the management of withdrawals from the Coldwater portion of the Basin. Additionally, Corona, in coordination with TVWD, adopted a Groundwater Management Plan (GWMP) in 2008 that covers the Basin.
WATER BUDGET
A water balance (or water budget) is a quantitative tabulation of all inflows, outflows, and storage change of a hydrologic system. This GSP contains a detailed water balance for both the groundwater system and surface water system of the Basin. The water budgets were developed for time periods representing historical, current, future no project (baseline), and future growth plus climate change (growth plus climate change) conditions.
In the Bedford MA, the major inflow to the groundwater budget is percolation from streams, especially during wet years. In recent years (2012 to 2018), reclaimed water percolation has become another major inflow. The major outflows include M&I pumping and groundwater discharge to streams. Historically, agricultural pumping also contributed to outflow from the Basin, but this decreased to a negligible amount by 2007. Groundwater storage in the Bedford MA increased slightly during the historical period (Figure ES-3), primarily as a result of the decrease in total groundwater pumping. Outflows in the future scenarios (baseline and growth plus climate change) are predicted to increase in response to increased pumping.
However, as shown in Figure ES-3, the Basin is still expected to have a positive change in storage (more inflow than outflow) in the future, even in growth and climate change Bedford-Coldwater GSP ES-5
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projections. This future increase in storage is due to continued groundwater management and increased imported water use in the Basin.
Figure ES-3. Cumulative Storage Change: Bedford Management Area In the Coldwater MA, percolation from streams occurs as infrequent, episodic events; stream percolation can range from 15,000 acre-feet (AF) in wet years to zero in dry years. M&I pumping has dominated outflows in this MA, although it has decreased from its peak in the late 1990s. Similar to the Bedford MA, agricultural pumping was a significant outflow historically, but decreased to a negligible amount by 2001.
Estimated historical storage in the Coldwater MA declined by a cumulative total of 60,000 AF from 1990 to 2004, as shown in Figure ES-4. EVMWD and Corona entered into an agreement to limit pumping in the MA to a periodically re-calculated safe or sustainable yield in 2008. As a result, there was little additional cumulative decline from 2005 to 2018. In contrast, storage in both future scenarios is predicted to increase steadily over the 50 year future simulation periods. Inflows are estimated to exceed outflows in the future because of increased urban recharge and continued limitation of pumping. The rate of storage increase is slightly higher under the growth plus climate change scenario relative to the baseline scenario, which can be attributed to increased urban return flow recharge.
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Figure ES-4. Cumulative Storage Change: Coldwater Management Area
SUSTAINABLE MANAGEMENT CRITERIA (SMC)
This GSP defines sustainable management as the use and management of groundwater in a manner that can be maintained without causing undesirable results, which are defined as significant and unreasonable effects caused by groundwater conditions occurring throughout the Basin, specifically in consideration of the following sustainability indicators:
• Chronic lowering of groundwater levels indicating a significant and unreasonable depletion of supply.
• Significant and unreasonable reduction of groundwater storage. • Significant and unreasonable seawater intrusion. 1
• Significant and unreasonable land subsidence that substantially interferes with surface land uses.
• Significant and unreasonable degraded water quality, including the migration of contaminant plumes that impair water supplies.
• Depletions of interconnected surface water that have significant and unreasonable adverse impacts on beneficial uses of the surface water.
For these sustainability indicators, a GSP must develop quantitative sustainability criteria that allow the GSA to define, measure, and track sustainable management. These criteria include the following:
1 Seawater intrusion is noted, but no risk of seawater intrusion exists in this inland basin.
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• Undesirable Result – significant and unreasonable conditions for any of the six sustainability indicators.
• Minimum Threshold (MT) – numeric value used to define undesirable results for each sustainability indicator.
• Measurable Objective (MO) – specific, quantifiable goal to track the performance of sustainable management.
The sustainability indicators and SMC are clearly defined and provide a quantitative analysis of the Basin’s sustainability. As the Basin is currently sustainable, and has been managed sustainably, the following sustainability criteria are defined in to avoid future undesirable results:
• The Minimum Threshold for defining undesirable results relative to chronic lowering of groundwater levels is defined by operational considerations to maintain water levels at or above current pump intakes or screen bottoms (whichever is higher) in municipal water supply wells represented by frequently monitored Key Wells.
Undesirable results are indicated when two consecutive exceedances occur in each of two consecutive years, in two-thirds or more of the currently monitored wells in each Management Area.
• The Minimum Threshold for reduction of groundwater storage for all Management Areas is fulfilled by the minimum threshold for groundwater levels as proxy. • The Minimum Threshold for land subsidence is defined as a cumulative decline equal to or greater than one foot of decline since 2015, which represents current conditions and the SGMA start date. This is equivalent to a rate of decline equal to or greater than 0.2 feet in any five-year period. The extent of cumulative subsidence across the Basin will be monitored and evaluated using Interferometric Synthetic Aperture Radar (InSAR) data available through the SGMA Data Viewer during the 5- year GSP updates. Subsidence as a result of groundwater elevation decline is closely linked to groundwater levels and it is unlikely that significant inelastic subsidence would occur if groundwater levels remain above their minimum thresholds. • The Minimum Thresholds for degradation of water quality address nitrate and total dissolved solids (TDS) for the entire Basin.
o The Nitrate Minimum Threshold (in both Management Areas) is defined as 5-year average concentrations of all monitored wells not exceeding the 10 milligrams per liter (mg/L) drinking water maximum contaminant level (MCL) for Nitrate as Nitrogen.
o The TDS Minimum Threshold (in both Management Areas) is defined as the 5-year average concentrations not exceeding the 1,000 mg/L secondary MCL for TDS.
• The Minimum Threshold for depletion of interconnected surface water is the amount of depletion associated with the lowest water levels recorded during the 2010 to 2015 drought. Specifically, undesirable results would occur if more than half of monitored wells near Temescal Wash had static water levels lower than 35 feet below the adjacent riparian vegetation ground surface elevation for a period of more than one year.
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MONITORING NETWORK
The monitoring network for GSP implementation has been established to document groundwater and related surface conditions as relevant to the sustainability indicators, MTs, and MOs. The components of the monitoring network are built from existing programs and will be carried out by the BCGSA.
The BCGSA has actively engaged in assessment and improvement of its monitoring network.
This process has been intensified as part of the GSP, given the need to identify data gaps and to assess uncertainty in setting and tracking sustainability criteria. Monitoring improvements such as adding or replacing monitoring infrastructure are part of GSP implementation and will be reviewed and updated for each five-year GSP update.
PROJECTS AND MANAGEMENT ACTIONS
During the preparation of the GSP, the BCGSA identified five specific management actions (Actions) and three projects (Projects) to achieve the sustainability goal. The Actions are generally focused on data collection, storage and reporting of information necessary to monitor sustainability, and assessment of when Actions may be necessary (i.e., when MTs are approached or exceeded). The projects are generally designed to reduce uncertainty in areas where data gaps have been identified during development of the GSP. The Projects and Actions in the GSP are as follows:
• Action 1 – Provide for Collection, Compilation, and Storage of Information Required for Annual Reports and Submit Annual Reports;
• Action 2 – Routinely Record Groundwater Levels and Take Action if Necessary; • Action 3 – Monitor Selected Groundwater Quality Constituents and Coordinate with the Regional Water Quality Control Board as Appropriate; • Action 4 – Track Trends in Groundwater Levels near Temescal Wash and Take Action as Necessary;
• Action 5 – Review Interferometric Synthetic Aperture Radar (InSAR) Data on the California Department of Water Resources (DWR) Dataviewer During 5-Year Updates;
• Project 1 – Investigate Groundwater/Surface Water Interaction at Temescal Wash and Install Monitoring Wells;
• Project 2 – Initiate a Survey of Active Private Wells; and • Project 3 – Evaluation of the Effects of Aggregate Pits on Groundwater Flow and Quality.
The Projects and Actions will be implemented by a combination of existing resources from the three agencies within the plan area and contracted resources.
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IMPLEMENTATION
The official adoption of the GSP by the BCGSA will initiate Plan implementation. After submittal of the GSP to DWR, and during the DWR review period, the BCGSA will continue to communicate with stakeholders via the BCGSA’s website and begin implementing the projects and management actions described in this GSP. The Plan will be implemented to sustainably manage groundwater in the Basin under the authority of the BCGSA and its member agencies.
The BCGSA is required to submit an annual report to DWR by April 1st of each year following adoption of the GSP. The first annual report will be due in April of 2022. The BCGSA has committed to implementing the GSP upon adoption and completing the projects and management actions necessary to monitor and maintain sustainability within the first 5 years of initiation of the GSP.
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1. INTRODUCTION
The Sustainable Groundwater Management Act (SGMA), effective January 1, 2015, was enacted in California to regulate and sustainably manage groundwater basins throughout the state. SGMA provides a framework to guide local public agencies and newly created Groundwater Sustainability Agencies (GSAs) in the management of their underlying groundwater basins, especially those considered critically affected as defined by the Department of Water Resources (DWR). The Bedford-Coldwater Groundwater Sustainability Agency (BCGSA) has elected to create a Groundwater Sustainability Plan (GSP) to maintain long-term groundwater sustainability in the Bedford-Coldwater Groundwater Subbasin (Basin, Figure 1-1) of the Elsinore Groundwater Basin.
1.1. PURPOSE OF THE GROUNDWATER SUSTAINABILITY PLAN
SGMA requires local agencies of all basins designated as high- or medium-priority to develop a GSP to halt groundwater overdraft and achieve sustainability within 20 years of implementing the plan. Although the Basin is designated as very low-priority and does not require a GSP, the BCGSA is committed to protecting and maintaining the current sustainable conditions into the future and has opted to create and implement a GSP.
The purpose of the GSP is to provide basic information on the groundwater conditions in the Basin and to provide a plan or roadmap to maintain sustainability of beneficial use of groundwater in accordance with SGMA. The goal of the GSP is to promote Basin health by maintaining the generally balanced water budget, continue to prevent chronic overdraft, and avoid undesirable results which SGMA has divided into the six categories, represented in Figure 1-2 below.
!"a$
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Temescal Canyon Road
Cajalco Road
Temescal Canyon Road
Trilogy Parkway
Temescal Canyon Road
Estelle Mountains
Santa Ana Mountains
Bedford-Coldwater
Groundwater Basin
Path: T:\Projects\Bedford Coldwater GSP 80802\GIS\Maps\Figures\GSP Figures\Chapter 1 and 2 - ES, Intro, and, Plan Area\Figure 1-1 BC GW Basin and Adjacent Basins_r1.mxd Figure 1-1
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Groundwater Basin, GSA,
and Adjacent Basins
Bedford-Coldwater Basin and
Groundwater Sustainability Agency
Temescal Basin
Elsinore Valley Basin
("N
("N
0 1,750 3,500
Scale in Feet
1-2
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Figure 1-2. SGMA Undesirable Results
The GSP assesses sustainability related to each of the categories listed above, defines thresholds for maintaining sustainability, outlines groundwater monitoring protocols, best management practices, management actions and projects designed to improve monitoring capabilities and/or to protect and enhance groundwater conditions. The GSP also includes a schedule and cost estimate for plan implementation. Each element of the GSP is designed to promote basin health and achieve and maintain the sustainability goal established for the Basin by the BCGSA.
1.2. SUSTAINABILITY GOAL
The BCGSA prepared this GSP with the goal of sustaining groundwater resources for the current and future beneficial uses of the Bedford-Coldwater Basin in a mannerthat is adaptive and responsive to the following objectives:
• Provide a long-term, reliable and efficient groundwater supply for municipal, industrial, and other uses;
• Provide reliable storage for water supply resilience during droughts and shortages; • Protect groundwater quality;
• Support beneficial uses of interconnected surface waters; and • Support integrated and cooperative water resource management.
This goal is consistent with SGMA and is based on information from the Plan Area, Hydrogeologic Conceptual Model, Groundwater Conditions, and Water Budget sections of this GSP that:
• Identify beneficial uses of Basin groundwater and document the roles of local water and land use agencies;
• Describe the local hydrogeologic setting, groundwater quality conditions, groundwater levels and storage, and inflows and outflows of the Basin; and • Document the ongoing water resource monitoring and conjunctive management of groundwater, local surface water, recycled water and especially imported water sources that help protect groundwater quality and maintain water supply.
Lowering
Groundwater
Levels
Reduction of
Groundwater
Storage
Seawater
Intrusion
Degraded
Water Quality
Land
Subsidence
Surface Water
Depletion
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1.3. AGENCY INFORMATION
This section provides contact information, management structure, and legal authority of the BCGSA.
BCGSA Mailing Address: Bedford-Coldwater Groundwater Sustainability Authority 31315 Chaney Street
Lake Elsinore, CA 92530
1.3.1. Organization and Management Structure
The BCGSA consists of representatives from the three agencies overlying the Basin: The City of Corona (Corona), Elsinore Valley Municipal Water District (EVMWD), and Temescal Valley Water District (TVWD). The BCGSA is governed by a Board of Directors (Board), composed of three governing members, one member appointed by the representatives from each agency.
The governing Board members will serve without terms, and at the discretion of the agency which appointed them. The Board designated a consultant to act as the Administrator for the BCGSA and provide administrative services as needed and required by SGMA and the BCGSA until the GSP is adopted. Information about the current BCGSA Board members can be found on the BCGSA website: https://www.bedfordcoldwatergsa.com/about-us/.
The point of contact for the BCGSA is the Plan Manager, Margie Armstrong. At the time of writing this GSP, the following is the current contact information:
BCGSA Plan Manager: Margie Armstrong
Deputy Treasurer
Bedford-Coldwater Subbasin GSA
31315 Chaney Street
Lake Elsinore, CA 92530
951-674-3146 Ext 8306
[email protected]
http://www.evmwd.com/
An organizational chart for the BCGSA is presented on Figure 1-3 below.
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Figure 1-3. BCGSA Management Structure
1.3.2. Legal Authority
A Joint Powers Agreement (Agreement) to create a Joint Powers Authority (JPA) for the management of the Basin was entered into as of February 28, 2017 (Appendix A). The Agreement to form the BCGSA is by and between Corona, a California General Law City organized and existing under the laws of the State of California, EVMWD, a Municipal Water District organized under Water Code §§ 71000 et seq., and TVWD, a California Water District organized under California Water Code §§ 34000 et seq.. BCGSA signed a resolution to become the GSA for the Basin on March 29, 2017 (Appendix B, BCGSA 2017).
1.3.3. GSP Implementation Cost Estimate and Schedule
GSP implementation cost and schedule is described in detail in Section 9, Plan Implementation. Costs associated with implementing the GSP are considered to be either continually ongoing (operating) costs, or GSP implementation costs associated with specific management actions and projects. Annual operating costs in 2021 dollars are expected to be approximately $60,000. Annual implementation of management actions is estimated at approximately $266,000 per year, while total costs for recommended, one-occurrence projects is approximately $990,000 (including the first 5-Year GSP update). Estimated costs for years after the 5-Year GSP update will be reevaluated within the first 5-Year GSP update.
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The BCGSA has committed to implementing the GSP upon adoption and completing the projects and management actions necessary to monitor and maintain sustainability within the first 5 years of initiation of the GSP. A preliminary schedule for implementation is provided in Section 9 as Figure 9-1.
1.4. GSP ORGANIZATION
This GSP was prepared according to guidance documents provided by DWR (DWR 2016a). The following outlines the GSP contents:
• Section 1 – Introduction, purpose of the GSP, sustainability goal, agency information, and GSP organization.
• Section 2 – Plan Area description, water use sectors, water supply sources, water resources monitoring and management programs, current general plans, other GSP elements.
• Section 3 – Hydrogeologic Conceptual Model, description of the physical basin setting including surface water features, soils, geologic setting, faults, and aquifers, defined basin bottom, recharge and discharge areas, and cross sections. • Section 4 – Current and Historical Groundwater Conditions, discussion of groundwater elevations, land subsidence, groundwater quality and current monitoring, constituents of concern regarding water quality, interconnection of surface water and groundwater and the effects on groundwater dependent ecosystems (GDEs).
• Section 5 – Water Budget, discussion of the water budget, groundwater model, surface water and groundwater balance, change in groundwater storage, and estimate of sustainable yield.
• Section 6 – Sustainable Management Criteria, sustainability goal, sustainability criteria for the six undesirable results.
• Section 7 – Monitoring Network, discussion of the monitoring that will continue to assess sustainability in the future.
• Section 8 – Projects and Management Actions, descriptions of projects and management actions for the Basin.
• Section 9 – Plan Implementation, estimate of GSP implementation costs, schedule, plan for annual reporting and periodic evaluations.
• Section 10 – References
The GSP Preparation Checklist providing the chapter locations for GSP content requirements is provided in Table 1-1 and the GSP Elements Guide detailing GSP content in comparison to SGMA articles is included in Appendix C. Figures in following sections are placed at the end of the section.
Table 1-1. GSP Preparation Checklist
GSP
Regulations
Section
Water Code
Section Requirement
352.2 Monitoring
Protocols
354.4 General
Information
354.6 Agency
Information
354.8(a) 10727.2(a)(4) Map(s)
354.8(b) Description of the
Plan Area
354.8(c)
354.8(d)
354.8(e)
10727.2(g) Water Resource
Monitoring and
Management
Programs
354.8(f) 10727.2(g) Land Use Elements
or Topic
Categories of
Applicable General
Plans
354.8(g) 10727.4 Additional GSP
Contents
354.10 Notice and
Communication
- Area covered by GSP (Figure 1-1)
- Adjudicated areas, other agencies within the basin, and areas covered by an Alternative (Figure 1-1) - Jurisdictional boundaries of federal or State land (Figure 2-1) - Existing land use designations (Figures 2-7, 2-8)
- Density of wells per square mile (Figures 2-3 through 2-6) Section 2
Article 5. Plan Contents, Subarticle 1. Administrative Information (Continued) - Summary of jurisdictional areas and other features
Article 5. Plan Contents, Subarticle 1. Administrative Information - List of references and technical studies Section 10
- GSA mailing address
- Organization and management structure
- Contact information of Plan Manager
- Legal authority of GSA
- Estimate of implementation costs
Section 1.3
Section 2.1
- Description of water resources monitoring and management programs - Description of how the monitoring networks of those plans will be incorporated into the GSP - Description of how those plans may limit operational flexibility in the basin - Description of conjunctive use programs
Section 2.1.4
Section 2.1.4.1
Section 2.1.4.2
Section 2.1.6
- Summary of general plans and other land use plans
- Description of how implementation of the GSP may change water demands or affect achievement of sustainability and how the GSP addresses those effects
- Description of how implementation of the GSP may affect the water supply assumptions of relevant land use plans
- Summary of the process for permitting new or replacement wells in the basin - Information regarding the implementation of land use plans outside the basin that could affect the ability of the Agency to achieve sustainable groundwater management Section 2.1.5
Section 2.1.5.3
Section 2.1.5.4
Section 2.1.5.5
Section 2.1.6
Description Section(s) or Page
Number(s) in the GSP
Article 3. Technical and Reporting Standards
- Monitoring protocols adopted by the GSA for data collection and management - Monitoring protocols that are designed to detect changes in groundwater levels, groundwater quality, inelastic surface subsidence for basins for which subsidence has been identified as a potential problem, and flow and quality of surface water that directly affect groundwater levels or quality or are caused by groundwater extraction in the basin
Section 7.2
Description of Actions related to:
- Control of saline water intrusion
- Wellhead protection
- Migration of contaminated groundwater
- Well abandonment and well destruction program
- Replenishment of groundwater extractions
- Conjunctive use and underground storage
- Well construction policies
- Addressing groundwater contamination cleanup, recharge, diversions to storage, conservation, water recycling, conveyance, and extraction projects
- Efficient water management practices
- Relationships with State and federal regulatory agencies - Review of land use plans and efforts to coordinate with land use planning agencies to assess activities that potentially create risks to groundwater quality or quantity - Impacts on groundwater dependent ecosystems
Section 2.1.6
- Description of beneficial uses and users
- List of public meetings
- GSP comments and responses
- Decision-making process
- Public engagement
- Encouraging active involvement
- Informing the public on GSP implementation progress
Section 2.1.7
Appendix J (pending)
Appendix J (pending)
Section 1.3.1
Appendix D
Section 2.1.7
Section 2.1.7
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1-7
GSP
Regulations
Section
Water Code
Section Requirement Description Section(s) or Page
Number(s) in the GSP
354.14 Hydrogeologic
Conceptual Model
9 10727.2(a)(5) Map of Recharge
Areas
10727.2(d)(4) Recharge Areas
354.16 10727.2(a)(1)
10727.2(a)(2)
Current and
Historical
Groundwater
Conditions
354.18 10727.2(a)(3) Water Budget
Information
10727.2(d)(5) Surface Water
Supply
354.20 Management
Areas
354.24 Sustainability Goal
354.26 Undesirable
Results
354.28 10727.2(d)(1)
10727.2(d)(2)
Minimum
Thresholds
354.30 10727.2(b)(1)
10727.2(b)(2)
10727.2(d)(1)
10727.2(d)(2)
Measureable
Objectives
Article 5. Plan Contents, Subarticle 2. Basin Setting
- Description of the Hydrogeologic Conceptual Model
- Two scaled cross-sections
- Map(s) of physical characteristics: topographic information, surficial geology, soil characteristics, surface water bodies, source and point of delivery for imported water supplies Section 3, Figure 3-8 and 3-
9 - Map delineating existing recharge areas that substantially contribute to the replenishment of the basin, potential recharge areas, and discharge areas
Figure 3-10
- Description of how recharge areas identified in the plan substantially contribute to the replenishment of the basin
Section 3.10
- Groundwater elevation data
- Estimate of groundwater storage
- Seawater intrusion conditions
- Groundwater quality issues
- Land subsidence conditions
- Identification of interconnected surface water systems - Identification of groundwater-dependent ecosystems
Section 4
- Description of inflows, outflows, and change in storage - Quantification of overdraft
- Estimate of sustainable yield
- Quantification of current, historical, and projected water budgets Section 5.7, Section 5.8,
and Section 5.9
- Description of surface water supply used or available for use for groundwater recharge or in-lieu use Section 2.1.2.1, Section
3.11, Section 5.6.2
- Reason for creation of each management area
- Minimum thresholds and measurable objectives for each management area - Level of monitoring and analysis
- Explanation of how management of management areas will not cause undesirable results outside the management area
- Description of management areas
Section 5.4
Article 5. Plan Contents, Subarticle 3. Sustainable Management Criteria - Description of the sustainability goal Section 6.1.1
- Description of undesirable results
- Cause of groundwater conditions that would lead to undesirable results - Criteria used to define undesirable results for each sustainability indicator - Potential effects of undesirable results on beneficial uses and users of groundwater Section 6.2.1
Section 6.2.2
Section 6.2.3
Section 6.2.4
- Description of each minimum threshold and how they were established for each sustainability indicator - Relationship for each sustainability indicator
- Description of how selection of the minimum threshold may affect beneficial uses and users of groundwater - Standards related to sustainability indicators
- How each minimum threshold will be quantitatively measured Sections 6.2 through 6.7
- Description of establishment of the measureable objectives for each sustainability indicator - Description of how a reasonable margin of safety was established for each measureable objective - Description of a reasonable path to achieve and maintain the sustainability goal, including a description of interim milestones
Sections 6.2 through 6.7
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Table 1-1. GSP Preparation Checklist
GSP
Regulations
Section
Water Code
Section Requirement Description Section(s) or Page
Number(s) in the GSP
354.34 10727.2(d)(1)
10727.2(d)(2)
10727.2(e)
10727.2(f)
Monitoring
Networks
354.36 Representative
Monitoring
354.38 Assessment and
Improvement of
Monitoring
Network
354.44 Projects and
Management
Actions
354.44(b)(2) 10727.2(d)(3)
357.4 10727.6 Coordination
Agreements - Shall
be submitted to
the Department
together with the
GSPs for the basin
and, if approved,
shall become part
of the GSP for
each participating
Agency.
Article 5. Plan Contents, Subarticle 4. Monitoring Networks - Description of monitoring network
- Description of monitoring network objectives
- Description of how the monitoring network is designed to: demonstrate groundwater occurrence, flow directions, and hydraulic gradients between principal aquifers and surface water features; estimate the change in annual groundwater in storage; monitor seawater intrusion; determine groundwater quality trends; identify the rate and extent of land subsidence; and calculate depletions of surface water caused by groundwater extractions
- Description of how the monitoring network provides adequate coverage of Sustainability Indicators - Density of monitoring sites and frequency of measurements required to demonstrate short-term, seasonal, and long-term trends
- Scientific rational (or reason) for site selection
- Consistency with data and reporting standards
- Corresponding sustainability indicator, minimum threshold, measureable objective, and interim milestone - Location and type of each monitoring site within the basin displayed on a map, and reported in tabular format, including information regarding the monitoring site type, frequency of measurement, and the purposes for which the monitoring site is being used
- Description of technical standards, data collection methods, and other procedures or protocols to ensure comparable data and methodologies
Section 7.1
Section 7.0
- Description of representative sites
- Demonstration of adequacy of using groundwater elevations as proxy for other sustainability indicators - Adequate evidence demonstrating site reflects general conditions in the area Section 7.3
- Review and evaluation of the monitoring network
- Identification and description of data gaps
- Description of steps to fill data gaps
- Description of monitoring frequency and density of sites Section 7.5
Section 7.5.1
Section 7.5.2
Section 7.1.1
Article 5. Plan Contents, Subarticle 5. Projects and Management Actions Article 8. Interagency Agreements
Coordination Agreements shall describe the following:
- A point of contact
- Responsibilities of each Agency
- Procedures for the timely exchange of information between Agencies - Procedures for resolving conflicts between Agencies
- How the Agencies have used the same data and methodologies to coordinate GSPs - How the GSPs implemented together satisfy the requirements of SGMA - Process for submitting all Plans, Plan amendments, supporting information, all monitoring data and other pertinent information, along with annual reports and periodic evaluations - A coordinated data management system for the basin
- Coordination agreements shall identify adjudicated areas within the basin, and any local agencies that have adopted an Alternative that has been accepted by the Department N/A
- Description of projects and management actions that will help achieve the basin’s sustainability goal - Measureable objective that is expected to benefit from each project and management action - Circumstances for implementation
- Public noticing
- Permitting and regulatory process
- Time-table for initiation and completion, and the accrual of expected benefits - Expected benefits and how they will be evaluated
- How the project or management action will be accomplished. If the projects or management actions rely on water from outside the jurisdiction of the Agency, an explanation of the source and reliability of that water shall be included.
- Legal authority required
- Estimated costs and plans to meet those costs
- Management of groundwater extractions and recharge
Section 8.0
- Overdraft mitigation projects and management actions Section 8.2 T:\Projects\Bedford Coldwater GSP 80802\Deliverables\GSP\Complete GSP\Tables\Table 1-1 20210525.xlsx H Water Resources
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Table 1-1. GSP Preparation Checklist
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2. PLAN AREA
The following section, consistent with GSP Regulations §354.8, provides a description of the Plan Area.
The Bedford-Coldwater Subbasin (Basin) has been the focus of historical and ongoing collaborative groundwater basin management among three key agencies: City of Corona (Corona), Elsinore Valley Municipal Water District (EVMWD), and Temescal Valley Water District (TVWD). As noted in Chapter 1 of this Groundwater Sustainability Plan (GSP), the Basin is currently listed by the Department of Water Resources (DWR) as a very low priority groundwater basin. Therefore, preparation of a GSP is not required. The agencies that have been collaborating to manage the Basin, through the Bedford-Coldwater Groundwater Sustainability Agency (BCGSA), have confirmed their collective dedication to management for groundwater sustainability and have decided to prepare a GSP.
2.1. DESCRIPTION OF THE PLAN AREA
The following provides a general description of the Bedford-Coldwater Basin, including local jurisdictions, water resource management and monitoring programs, well permitting procedures, general plans and otherland use plans, and additional groundwater management elements.
2.1.1. Geographic Area
Figure 1-1 shows the boundaries of the Plan Area, namely the Bedford-Coldwater Groundwater Subbasin located in western Riverside County. Figure 1-1 also shows the adjacent Temescal Basin to the northwest (separated by a groundwater divide near Bedford Wash) and Elsinore Valley Subbasin located on the southern boundary. Both the Elsinore Valley Groundwater Sustainability Agency (GSA) and Temescal Subbasin GSA are in the process of developing GSPs for their respective subbasins. Bedford-Coldwater Basin is bound on the east and west by consolidated rocks of Estelle Mountain and the Santa Ana Mountains, respectively. The major drainage is Temescal Wash, traverses the three groundwater basins along its 26-mile course from Lake Elsinore to the Prado Wetlands on the Santa Ana River.
2.1.2. Jurisdictional Agencies
This section identifies agencies with land use management responsibilities. There are no economically distressed areas, disadvantaged communities, or severely disadvantaged communities in the Basin.
County. The Basin is located wholly within Riverside County. Riverside County has jurisdiction for land use planning for unincorporated areas. Riverside County also has responsibility for small water systems in the County that have between 15 and 199 service connections and those serving restaurants, schools, and industry. It also provides limited regulatory oversight to those water systems serving between 5 and 14 service connections. The County oversees Bedford-Coldwater GSP 2-2
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on-site wastewater treatment systems (OWTS) through its Department of Environmental Health. The Department of Environmental Health also evaluates existing residential water wells and makes a determination if the water meets certain minimum standards.
City of Corona. Figure 2-1 shows the boundaries of the other jurisdiction that has land use management responsibilities, the City of Corona. General plan elements relevant to the GSP are discussed in Section 2.1.3. In addition to land use planning, Corona Department of Water and Power is responsible for stormwater management, sewage collection, and production and distribution of potable water for Corona, including the portion within the Basin.
Federal Lands. Federal lands within the Basin include United States Department of Agriculture Forest Service – Cleveland National Forest. The area is managed by the Forest Service.
Tribal Lands. There are no tribal lands in the Basin, however some tribes are included as stakeholders on the list of interested parties. The list of interested parties was developed to encourage public participation from any and all local and regional agencies, entities, and individuals. The list included tribes with land in the region even though they do not have land within the Basin. The BCGSA agencies have a long history of coordination with the regional tribal entities, and they always inform these entities of upcoming planning and/or infrastructure projects. The regional tribal entities take an interest in planning and infrastructure projects within the Basin and surrounding areas because there are important cultural resource sites within these areas. The BCGSA agencies and regional tribal entities coordinate to assess infrastructure project sites prior to groundbreaking to identify and protect potential cultural resources.
California Conservation Easement. According to the California Conservation Easement Database (CCED) there is an area of private land, Lee Lake Easement, with deed-based restrictions to limit land uses to those compatible with its status as open space. Lands under easement may be actively farmed, grazed, forested, or held as nature reserves. Easements are typically held on private lands with no public access. CCED represents California in the National Conservation Easement Database (NCED 2019), a national inventory of lands conserved as easements. NCED is managed by a consortium of non-governmental organizations including: Ducks Unlimited, the Trust for Public Land, Defenders of Wildlife, Conservation Biology Institute, and NatureServe.
Other. There are no state park lands or land owned by the California Department of Fish & Wildlife (CDFW) within the Basin.
2.1.3. Disadvantaged Communities
There are no disadvantaged communities (DACs) or severely disadvantaged communities (SDACs) mapped within the Basin (DWR 2019c).
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2.1.4. Water Supply Sources
Sources for water supply for agricultural, Municipal and Industrial (M&I), and domestic uses include groundwater, imported water, and recycled water. Metropolitan Water District of Southern California (Metropolitan) is the wholesaler for imported water and its sources of water include the Colorado River and the State Water Project. Both Corona and TVWD receive imported water from Metropolitan for distribution in the Basin. EVMWD also receives imported water from Metropolitan through Western Municipal Water District (WMWD), but only distributes imported water within the Basin when groundwatersupply to domestic users is insufficient.
Water Providers. The BCGSA was created through a Joint Powers Authority agreement between Corona, EVMWD, and TVWD. Figure 2-2 shows the service areas of these providers.
Othersmallsystems are operated by private mutual water companies and some communities do not have water purveyors and systems that provide water service. These small systems and communities—plus rural businesses, schools, parks, and residents—rely on private wells and groundwater.
• City of Corona. A portion of the City of Corona overlies the Basin, amounting to 1,213 acres or about 5 percent of the city’s area. Corona maintains three treatment facilities and serves water to more than 150,000 residents with water supply from a combination of imported water and groundwater.
• Temescal Valley Water District (TVWD). TVWD is the primary purveyor in the BCGSA. TVWD, formed in 1965 as Lee Lake Water District, provides water and wastewater services to the residents of the Temescal Valley in an area covering approximately 6,730 acres.
• Elsinore Valley Municipal Water District (EVMWD). EVMWD supplies water to customers within the Basin from a combination of groundwater and imported water supply sources.
Groundwater. Groundwater currently is a source of water supply in the Basin. Corona, EVMWD, and TVWD all pump groundwater from the Basin. Corona and EVMWD distribute this supply to users within and outside the Basin, while TVWD only supplies groundwater to users within the Basin. There are also a few private users that pump groundwater within the Basin. Groundwater produced within the Basin is used to supply municipal, agricultural, mining, recreational, and domestic uses and users throughout the Basin and in the neighboring Temescal and Elsinore Valley Subbasins (DWR 2019a).
Water Supply Wells. Figure 2-3 shows the density of water supply wells in and around the Plan Area; this map is based on the DWR Well Completion Report Map Application tool (DWR 2019b). As indicated, the density of supply wells is generally less than nine wells per square mile. Relatively high densities occur around the northern margins of the Basin, where the Corona and EVMWD wells are located. Figures 2-4, 2-5, and 2-6 show the estimated density of domestic wells, production wells, and public wells. Most of the production wells, as Bedford-Coldwater GSP 2-4
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classified by DWR, are presumably irrigation wells but also include some industrial and commercial wells.
Outside of the three major purveyors, there is only one public water system; Glen Ivy Hot Springs has one well and serves an estimated population of 750 people. The Glen Ivy Hot Springs well is located in the southwestern portion of the Basin (Figure 2-2).
The BCGSA is aware that there are a small number of private wells used for non-potable supply in the Basin. However, a systematic well inventory identifying all active private wells has not been completed to date. This has been identified as a data gap in the GSP, as described in Section 6.2.7.1. The GSP also includes a project to address this data gap with a survey and inventory of active private wells throughout the Basin (Project 2, Section 8.7). This project was designed to locate and characterize the construction and use of existing private wells so that they can be included in sustainable management of the Basin.
Imported Water. Corona, TVWD, and EVMWD rely on imported water from Metropolitan.
Metropolitan imports water to Southern California from two main sources: the Sacramento and San Joaquin Rivers through the State Water Project and the Colorado River via the Colorado River Aqueduct. Corona receives imported water from Metropolitan through WMWD. Temescal Valley Water District receives State Water Project imported by Metropolitan and treated at the Henry J. Mills Treatment Plant in Riverside. EVMWD also receivesimported waterfrom Metropolitan through WMWD, but only distributes to domestic users if groundwater isinsufficient. Imported water and other water infrastructure are shown on Figure 2-7.
Recycled Water. Water recycling occurs in both Corona and TVWD. Recycled water use is a relatively small but increasing supply. In TVWD, recycled water is distributed to multiple sites within TVWD’s service area, including the Retreat Golf Course in the northern portion of the Basin and the Deleo Sports Park along Sycamore Creek in the south Basin (RMC and Woodard & Curran 2017).
2.1.5. Water Use Sectors
Water use sectors are defined in the GSP Regulations as categories of water demand based on the general land usesto which the wateris applied, including urban, industrial, agricultural, managed wetlands, managed recharge, and native vegetation. In the Basin, these are summarized as follows:
• Urban water use sectors are focused in the City of Corona area but extend through the center of the Basin.
• Areas of industrial water use are limited.
• Agricultural land uses comprise limited areas of citrus in the southwestern portion of the Basin (20.5 acres).
• There is no current managed aquifer recharge in the Basin. • Native vegetation, including rangeland, accounts for the remainder including upland areas and along streams.
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2.1.6. Water Resources Monitoring and Management Programs This section summarizes water resources monitoring and management in the Basin. Corona, EVMWD, and TVWD have entered into a Joint Powers Authority (JPA) agreement for the purpose of forming and executing the responsibilities of the BCGSA in accordance with the Sustainable Groundwater Management Act (SGMA). The BCGSA encompasses the entirety of the Bedford-Coldwater Subbasin of the Elsinore Groundwater Basin (Basin 8-004.2, DWR 2016b).
Groundwater has been an important component of water supply in the Basin for more than 100 years. Until the 1970s, most of the groundwater production in the Basin was for agricultural supply (Todd and AKM 2008). A few well owners have also produced small amounts of groundwater for domestic use (Todd and AKM 2008). Production for municipal supply increased in the 1960s and 1970s and continues today.
For more than 50 years, Corona, EVMWD, and TVWD have relied on groundwater from the Basin for municipal use, and these agencies have long been responsible for managing groundwater conditions in the Basin. Corona and EVMWD have longstanding legal agreements for the management of withdrawals from the Coldwater area portion of the Basin. Additionally, Corona, in coordination with TVWD, adopted a Groundwater Management Plan (GWMP) in 2008 that covers the Basin.
In 2008, Corona and EVMWD established a legal agreement for the Coldwater portion of the Basin where most of the pumping occurs. The 2008 agreement is intended to enhance groundwater supply in order to maximize the sustainable use of groundwater. One of the goals of the agreement is to give Corona and EVMWD the ability to estimate annual groundwater production that ensures the sustainability of the Subbasin as a water supply.
Historically, Corona and EVMWD account for most of the production in the Basin, with Corona historically pumping about twice as much as EVMWD (Todd and AKM 2008). The agreement is based on this historical distribution of groundwater use and also recognizes the presence of private pumpers in the Basin. This agreement allots four percent of annual groundwater use to private pumpers.
The agreement encourages development of joint groundwater management projects to enhance recharge including the recharge of local surface water by both parties. EVMWD also has surface water rights in the Basin that can be used for recharge enhancement. The 2008 agreement provides a process for allocating production on an annual basis, accounting for production rights and a groundwater storage account. Every five years, the native safe yield is re-evaluated, and each party’s share of that yield is adjusted. To date, four annual reports have been completed (WEI 2016 and 2017b).
The only pumpers in the Bedford area of the Basin are the three agencies of the BCGSA.
Corona and TVWD service areas cover almost all of the Basin; those portions outside of these service areas are not within the service area of any local water agency. The BCGSA is coordinating with Riverside County and other agencies for these areas.
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2.1.6.1. Water Resource Monitoring
The overall objective of the monitoring networks for this GSP is to yield representative information about water conditions in the Basin as necessary to guide and evaluate GSP implementation. Water resource monitoring programs considered in this section include:
• Climate
• Surface water flows
• Imported water deliveries
• Water recycling
• Land use and cropping
• Wells and groundwater pumping
• Groundwater levels
• Land subsidence
• Water quality
Monitoring programs undertaken by local, state, and federal agencies are summarized below as they are relevant to the GSP.
Climate. Climate data collection stations and records have been reviewed and assessed for the Basin and surrounding areas. Previous investigations (Todd and AKM 2008, SAIC 2007, MWH 2004) have revealed substantial variability in precipitation amounts because of elevation differences between the Temescal Valley and the nearby Santa Ana Mountains.
These orographic effects result in significantly more precipitation on the upland areas of the watersheds that contribute to the Basin. However, operational rain gages exist only in EVMWD, Riverside, and at the top of Santiago Peak. Therefore, precipitation on the Basin itself and on the slopes of the Santa Ana Mountains below Santiago Peak must be modeled.
There are three currently active climate monitoring stations near the Basin: the Lake Elsinore station maintained by the National Oceanic Atmospheric Administration (NOAA),the Santiago Peak station maintained by Orange County, and the UC Riverside California Irrigation Management Information System (CIMIS). The Lake Elsinore and UC Riverside stationsinclude daily precipitation and evapotranspiration data; the Santiago Peak station collects monthly precipitation data. Monthly data for the Santiago Peak station are from January 1949 to current, with a slight lag on recent data. The Lake Elsinore station has daily data from January 1961 through current, and monthly data from 1897. The UC Riverside station has daily data from January 1986 through the present.
In addition to station-specific climate records, PRISM Climate Group (PRISM) data are also available. PRISM gathers climate observations from a wide range of monitoring networks, applies sophisticated quality control measures, and develops spatial climate datasets. These datasets incorporate a variety of modeling techniques and are available at multiple resolutions covering the period from 1895 to the present. These datasets include elevationvarying average precipitation isohyets that can be used to estimate or simulate precipitation throughout the watershed contributing to the Basin (PRISM 2018).
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Surface water flows. There are three streamflow gage stations near the Basin that are maintained by the United States Geological Survey (USGS 2018). These stations are located on Temescal Creek at about Main Street in Corona (USGS 11072100), Temescal Creek at Corona Lake (USGS 11071900), and San Jacinto River near Elsinore (USGS 11070500). These stations are all active and have records that begin in October 1980, November 2012, and January 1950, respectively.
Imported water deliveries. Imported water data and locations are monitored and available from Corona, EVMWD, and TVWD. Data are available monthly for Corona from 2005 to present, annually for TVWD from 1990 to present, and monthly for EVMWD from 1995 to present.
Recycled water. Corona and TVWD monitor and maintain records of recycled water use records and distribution locations. TVWD supplies non-potable recycled water to Retreat Golf Course on the north end of the Basin and the Deleo Sports Park along Sycamore Creek on the south end.
Wells and groundwater pumping. Groundwater production in the Basin is tracked by the Santa Ana River Watermaster, along with production in the rest of the watershed. WMWD currently coordinates groundwater use data collection.
Groundwater levels. Multiple agencies have historically monitored groundwater levels in the Basin, including Corona, EVMWD, USGS, and DWR.
Land use. Land use map data were collected from DWR, the California Department of Conservation Farmland Mapping and Monitoring Program (FMMP), and Riverside County. The available land use maps are indicated below:
• DWR: 2014 statewide land use mapping specifically developed for SGMA and GSPs. • FMMP: 1984, 1986, 1988, 1990, 1992, 1994, 1996, 1998, 2000, 2002, 2004, 2006, 2008, 2010, 2012, 2014, and 2016
• Riverside County: 1993 and 2000
Agricultural land is currently limited to approximately 20.5 acres of citrus/subtropical fruits (avocados and others) located on the southwestern edge of the Basin.
Land subsidence. While the potential for subsidence was recognized in the 2008 Groundwater Management Plan, it has not been a known issue in the Basin and ground surface elevations have not been monitored until recently. The TRE Altamira Interferometric Synthetic Aperture Radar (InSAR) Dataset, provided by DWR through the SGMA Data Viewer (DWR 2019c) and showing vertical ground surface displacement from June 2015 to June 2018, indicates that the Basin has been characterized by uplift over that period, likely reflecting tectonic factors. No known available sources of data indicate subsidence in the Basin.
Groundwater levels have been managed to stay above historical low levels to minimize the potential for ground settlement.
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Water quality. Groundwater quality in the Basin is monitored by the BCGSA agencies and Glen Ivy Hot Springs for compliance with State Water Resources Board Division of Drinking Water (DDW) requirements, and by facilities regulated by the Santa Ana Regional Water Quality Control Board (RWQCB).
Section 7 of this GSP documents the BCGSA monitoring network including how these objectives are met, descriptions of how each sustainability criteria will be monitored, and protocols for measurements.
2.1.6.2. Water Resources Management
This section describes the water resources management plans developed for the Plan Area; note that monitoring is addressed in Section 2.1.4.1.
Groundwater Management Plan, 2008. A GWMP was adopted in 2008 that covers the Basin.
The GMP included projects in the Bedford-Coldwater area including the Coldwater Subbasin Enhanced Recharge Project and Lee Lake Water District’s (now TVWD) Recharge to Bedford Subbasin. The GMP includes a quantitative water balance forthe area, but Bedford-Coldwater was not included in the numerical model developed to evaluate management programs and projects (Todd and AKM 2008).
Numerical Groundwater Modeling. There is no pre-existing numerical model that covers the entire Basin. A model of the Coldwater area was prepared by MWH in 2004 (MWH 2004), and this is the only numerical groundwater model covering any portion of the Basin. This model is documented in the Coldwater Basin Recharge Feasibility Study (MWH 2004). Numerical groundwater modeling for the purpose of the GSP is discussed in later chapters of this document.
Integrated Regional Water Management Plan (IRWMP), 2008. The IRWMP is a collaborative effort led by WMWD to identify regional and multi-benefit projects within member agencies service areas. Adopted in 2008, the IRWMP describes the region, provides goals and objectives, and identifies and evaluates projects and programs, including assessment of climate change.
The IRWMP identifies and prioritizes integrated regional projects for the watershed to maximize benefits to the broadest group of stakeholders in the region. Projects in the Bedford-Coldwater area include new water wells for Corona and managed recharge using recycled water infiltration in surface recharge basins or injection wells in the Bedford area (Kennedy/Jenks 2008a and 2008b).
Salt and Nutrient Management Plan (SNMP), 2017. SNMPs are required for groundwater basins throughout California and are intended to help streamline permitting of new recycled water projects while ensuring attainment of water quality objectives and protection of beneficial uses. The Upper Temescal Valley (UTV) SNMP prepared by WEI was a joint management plan, prepared by the EVMWD and the Eastern Municipal Water District (EMWD) (WEI 2017a).
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Wastewater services include the treatment of wastewater generated in their respective service areas and the subsequent discharge and reuse of treated wastewater, hereafter referred to as recycled water. The goal of the SNMP was to define management activities to comply with the total dissolved solids (TDS) and nitrate concentration objectives of the groundwater management zones (GMZs) and surface water bodies that are impacted by recycled water discharge and reuse in the UTV Watershed. The UTV SNMP recommends updates to the Water Quality Control Plan for the Santa Ana River Basin (Basin Plan) for water quality objectives for the entire upper Temescal Valley but does not provide objectives for individual GMZs. Water quality objectives and ambient water quality numbers were estimated for both TDS and nitrate for the entire UTV SNMP. Ambient water quality will be recomputed periodically.
Recycled Water Plans 2007 through 2016. TVWD prepared a series of plans for its recycled water, including assessment of system-wide impacts to groundwater quality. The planning documents include:
• Recycled Water Master Plan (Lee Lake Water District 2007). • Water System Master Plan (Lee Lake Water District 2014). • Temescal Valley Water District Comprehensive Water, Recycled Water, and Wastewater Cost of Service Study Report (Raftelis 2016).
Water Quality Control Plan for the Santa Ana Region. The Basin Plan was approved in 1994 and provides the framework for how surface water and groundwater quality in the Santa Ana Region should be managed to provide the highest water quality reasonably possible. The Basin Plan lists beneficial uses, describesthe water quality which must be maintained to allow those uses, provides an implementation plan, details State Water Resources Control Board (SWRCB) and RWQCB plans and polices to protect water quality, and presents surveillance and monitoring programs. The most recent update in 2004 revises groundwater basin boundaries, updates beneficial uses, and presents GMZ water quality objectives.
Urban Water Management Plans (UWMPs). The California Urban Water Management Planning Act requires preparation of UWMPs by urban water providers with 3,000 or more connections. The UWMPs, generally required every five years, provide information on water supply and water demand—past, present, and future—and allow comparisons as a basis for ensuring reliable water supplies. UWMPs examine water supply and demand in normal years and during one-year and multi-year droughts. UWMPS also provide information on per-capita water use, encourage water conservation, and present contingency plans for addressing water shortages. UWMPs have been prepared for Corona, TVWD, and EVMWD (KWC 2016, RMC and Woodard & Curran 2017, MWH 2016).
Despite challenges of drought, climate change, and environmental and legal factors, the three agencies have been able to provide reliable supply. This has been achieved by actively managing the portfolio of water supplies (groundwater, imported water, recycled water), by improving facilities (e.g., water treatment plants), and by promoting conservation.
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2.1.7. General Plans, Land Use Planning, and Well Permitting This section presents elements of General Plans and other land use planning in the Basin as relevant to groundwater sustainability. It summarizes the goals, objectives, policies, and implementation measures as variously described in the General Plans for Riverside County and the City of Corona, which together encompass the Basin. This section also summarizes local well permitting procedures and well ordinances.
2.1.7.1. Land Use
The Basin includes developed urban area, rural residential areas, and limited agriculture.
Figure 2-8 shows land use for 2014 (DWR 2017), which indicates that active agricultural land was limited to 20.5 acres of primarily subtropical orchard in the southwestern Basin.
2.1.7.2. General Plans
Land use planning within the Basin is guided by the General Plans for Riverside County and the City of Corona.
Riverside County General Plan. The Riverside County General Plan, adopted in 2015, incorporates a set of 15 Consensus Planning Principles drafted and endorsed by a coalition of Riverside County stakeholders. The General Plan encourages water use efficiency and requires that new developments incorporate water conservation techniques, such as groundwater recharge basins, use of porous pavement, drought tolerant landscaping, and water recycling, as appropriate. Additional policies ensure compliance with water efficient landscape principles, promote water conservation, and encourage the use of recycled water (Riverside County 2015).
Figure 2-9 shows general Land Use Planning Designations of the Riverside County General Plan throughout the Basin. As indicated, broad areas are designated as low and medium density residential with commercial and industrial areas near the freeway.
City of Corona General Plan. The Corona General Plan (EIP Associates 2020) was adopted in 2004 and is scheduled for update beginning in 2019. Figure 2-9 shows the Corona planning area, including portions of the Basin.
Goals, policies, and implementation measures with relevance to groundwater sustainability include:
• Policy 1.1.4 – Accommodate the types, densities, and mix of land uses that can be adequately supported by transportation and utility infrastructure (water, sewer, etc.) and public services (schools, parks, libraries, etc.) • Policy 1.5.14 – Require that developers demonstrate water conservation in the landscape design of their proposed projects, such as the use of drought-tolerant species.
• Policy 1.5.16 – Promote the use of recycled water for landscape irrigation, where feasible.
Bedford-Coldwater GSP 2-11
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In addition, there are several policies linked to the development of water infrastructure to ensure that water supply and treatment and delivery systems are sustainable and cost efficient. Other policies protect water quality and minimize impact on water resources.
2.1.7.3. General Plan Influences on GSA Ability to Achieve Sustainability Riverside County. The Riverside County General Plan addresses the importance of groundwater. The policies and implementation of the land use and public facilities/services elements indicate that the County role is to support and encourage local water agencies in ensuring that water supply is available. Similarly, with wastewater issues and protection of water quantity and quality, the County role is limited to encouragement of other agencies, developers, and landowners. The General Plan containslittle policy to manage land use within the constraints of available water supply other than to encourage drought resistant plants and the use of recycled water. In the Bedford-Coldwater area, the general plan provides land use designations in the Temescal Canyon Area Plan that were used to estimate future growth.
City of Corona. Corona serves a population that is predicted to increase from 170,100 in 2020 to about 182,800 residents by 2040 (KWC 2016). Some of this growth will be along the southern edge of Corona in the Eagle Creek area within and adjacent to the Basin. The general plan indicates that Metropolitan may build an additional treatment plant in the area to meet increased water demand. Corona land use policies generally are protective of agricultural land and hillsides, and conservation policies address water efficiency, water recycling, sustainability measures, and coordination with other agencies, including TVWD.
The increased development included in the general plans was simulated by the numerical model described in Section 5 and Appendix G. Based on these scenarios, the basin remains sustainable even with this projected development.
2.1.7.4. GSP Influences on General Plans
The BCGSA agencies will work together to implement this GSP and rely on their portfolio of watersupply to maintain sustainability. While future growth is expected based on the general plans, the agencies are committed to their agreements to limit pumping in Coldwater based on sustainable yield and import additional supplies to Bedford.
City of Corona. Implementation of the GSP will support Corona in providing continued groundwater that may be exported from the Basin to other areas of Corona. In addition, the GSP will ensure good quality water in sufficient quantities to serve its residents into the future, including drought periods.
Riverside County. The Riverside County General Plan generally assumes that local water agencies can ensure adequate high-quality water supplies into the future. The GSP provides additionalspecific information, documents potential challengesto watersupply, and explores undesirable results that may occur with future increases in groundwater demand.
Undesirable results will be defined with sustainability criteria, and if identified, will be addressed with management actions. These management actions may have ramifications for County land use planning. For example, GSPs are authorized within the GSP Plan Areas to impose well spacing requirements and control groundwater pumping and control extractions Bedford-Coldwater GSP 2-12
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by regulating, limiting, or suspending extractions from individual groundwater wells. Such regulation may present a constraint on potential land uses.
2.1.7.5. Well Permitting
Groundwater well permitting within the Basin is currently regulated by the Riverside County Department of Environmental Health as described in Riverside County Ordinance No. 682 (as amended through 684.4). The purpose of this ordinance is to provide minimum standards for construction, reconstruction, abandonment, and destruction of all wells in order to: (a) protect underground water resources, and (b) provide safe water to persons within Riverside County pursuant to the authority cited in Chapter 13801(c) of the California Water Code.
Wells regulated by Ordinance No. 682 include drinking water (domestic, industrial, community, or springs), agricultural, monitoring, and cathodic protection wells.
This ordinance is similar to the California State Guidelines for new wells under California Water Code Sections 13800 to 13806, which stipulates that local jurisdictions, including counties, cities, and water districts, have authority under the Water Code to adopt local well ordinances that meet or exceed the statewide standards. The Riverside County requirements exceed statewide standards with greater setback requirements from potentially contaminating activities such as septic systems.
The existing well permitting by the Riverside County Department of Environmental Health is the adopted standard for well permitting in this GSP.
2.1.8. Notice and Communication
As described in this section, groundwater is a source of supply in the Basin and supports a range of beneficial uses: agricultural, municipal, rural, and environmental. To some degree in the Basin, all land and property owners, residents, businesses, employees, farmers, and visitors are potentially affected by groundwater use.
The BCGSA have encouraged public participation in the ongoing planning and development activities supporting the GSP process. Domestic well owners were invited to participate and provide information on their wells, but none responded to the BCGSA data request. The BCGSA solicited information from private well owners during public meetings and through email and postal outreach but received no response. No well owners expressed concern with the GSP development.
Public workshops regarding development of the GSP have been conducted to encourage public participation and to provide educational outreach. Meeting notices have been provided to the list of interested parties that is maintained pursuant to Water Code Section 10723.2. Additionally, GSP development information and meeting notices have been posted to the BCGSA website.
Recognizing the importance of communication, multiple and diverse agencies and interested parties have been identified. These are listed in the BCGSA Stakeholder Outreach Plan, which is included as Appendix D.
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In addition to quarterly BCGSA Board of Directors meetings open to the public, the BCGSA held two dedicated public meetings presenting information related to and components of the GSP. Summaries of these public meetings are presented in Appendix E.
On June 7, 2021, the BCGSA notified stakeholders, including local City and County agencies, of their intent to adopt this GSP after a 90-day review period. One letter with comments on the GSP was received in early September. This letter along with responses from the BCGSA and indications of how the GSP has been modified are included in Appendix F.
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* The Public Land Survey System (PLSS) is a way of subdividing and describing land in the United States. PLSS Sections are one-mile square rectangular grids of 640 miles each. All lands in the public domain are subject to subdivision by this rectangular system of surveys, which is regulated by the U.S. Department of the Interior, Bureau of Land Management (BLM). ("N 0 1,750 3,500
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Estimated Density of
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* The Public Land Survey System (PLSS) is a way of subdividing and describing land in the United States. PLSS Sections are one-mile square rectangular grids of 640 miles each. All lands in the public domain are subject to subdivision by this rectangular system of surveys, which is regulated by the U.S. Department of the Interior, Bureau of Land Management (BLM). ("N 0 1,750 3,500
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Estimated Density of
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* The Public Land Survey System (PLSS) is a way of subdividing and describing land in the United States. PLSS Sections are one-mile square rectangular grids of 640 miles each. All lands in the public domain are subject to subdivision by this rectangular system of surveys, which is regulated by the U.S. Department of the Interior, Bureau of Land Management (BLM). ("N 0 1,750 3,500
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Statewide Crop Mapping 2014
DWR Standard Legend (modified for remote sensing)
R | Rice
P | Pasture
G | Grain and Hay Crops
T | Truck, Nursery, and Berry Crops
F | Field Crops
C | Citrus and Subtropical
D | Deciduous Fruits and Nuts
V | Vineyard
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Riverside County General Plan Designations
Very Low to Low Density Residential
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Corona General Plan Designations
Low to Medium Density Residential
Medium Density Residential
High Density Residential
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Figure 2-9
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Bedford-Coldwater GSP 3-1
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3. HYDROGEOLOGIC CONCEPTUAL MODEL
This chapter describes the hydrogeologic conceptual model of the Bedford-Coldwater Subbasin (Basin), including the basin boundaries, geologic formations and structures, and principal aquifer units. The chapter also addresses the interaction between groundwater and surface water and discusses groundwater recharge and discharge areas. The Hydrogeologic Conceptual Model presented in this chapter is a summary of relevant and important aspects of the Basin hydrogeology that influence groundwater sustainability. While the Chapter 1 Introduction and Chapter 2 Plan Area establish the institutional framework for sustainable management, this chapter, along with Chapter 4 Groundwater Conditions and Chapter 5 Water Budget, sets the physical framework.
The hydrogeologic conceptual model and basin conditions sections serve to document the technical aspects of the Basin’s hydrogeology. Later sections including the water budget and sustainability criteria will refer to and rely on the technical material contained here.
3.1. PHYSICAL SETTING AND TOPOGRAPHY
The Basin underlies a portion of the Elsinore Valley in western Riverside County and covers approximately 11 square miles. The Basin is adjacent to two other groundwater basins: the Temescal Subbasin of the Upper Santa Ana Basin to the north and the Elsinore Valley Subbasin of the Elsinore Basin to the south. Figure 3-1 illustrates the topography of the Basin and surrounding uplands.
Ground surface elevations along the valley floor are generally flat. Elevations range from approximately 1,000 feet above mean sea level (msl) at the northern boundary to approximately 1,200 feet above msl to the south, as shown by 200-foot contours on Figure 3-
1. The tributary watersheds reach up to more than 5,600 feet msl at the highest peak in the Santa Ana Mountain watersheds west of the Basin. Watersheds east of the Basin are significantly lower in elevation and rise only to about 1,800 feet.
Annual precipitation variesfrom below 12 inchesto more than 26 inches over the Study Area.
The long-term average annual rainfall is between 12 and 14 inches per year on the Basin floor and increases to more than 20 inches along the top of the local watersheds in the Santa Ana Mountains to the west.
3.2. SURFACE WATER FEATURES
Figure 3-2 shows surface water features including rivers, streams, springs, seeps, lakes, and ponds. The sub-watershed boundaries that drain into and through the Basin are shown on Figure 3-3.
The Basin covers a portion of the Santa Ana River watershed. Main tributaries to the Santa Ana River include Temescal Wash which flows through the Basin from the southeast to northwest and the Bedford Wash flowing toward the northeast along the northern boundary Bedford-Coldwater GSP 3-2
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of the Basin. These waterways are ephemeral and are dry much of the year, flowing mainly during the winter.
3.3. SOILS
Characteristics of soils are important factors in natural and managed groundwater infiltration (recharge) and are therefore an important component of a hydrogeologic system. Soil hydrologic group data from the U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey Geographic Database (SSURGO) (NRCS 2019) are shown on Figure 3-4. The soil hydrologic group is an assessment of soil infiltration rates determined by the water transmitting properties of the soil, which include hydraulic conductivity and percentage of clays in the soil, relative to sands and gravels. The groups are defined as:
• Group A – High Infiltration Rate: water is transmitted freely through the soil; soils typically less than 10 percent clay and more than 90 percent sand or gravel. • Group B – Moderate Infiltration Rate: water transmission through the soil is unimpeded; soils typically have between 10 and 20 percent clay and 50 to 90 percent sand.
• Group C – Slow Infiltration Rate: water transmission through the soil is somewhat restricted; soils typically have between 20 and 40 percent clay and less than 50 percent sand.
• Group D – Very Slow Infiltration Rate: water movement through the soil is restricted or very restricted; soils typically have greater than 40 percent clay, less than 50 percent sand.
The hydrologic group of the soil generally correlates with the potential forinfiltration of water to the subsurface. However, there is not necessarily a correlation between the soils at the ground surface and the underlying geology or hydrogeology.
3.4. GEOLOGIC SETTING
The Basin is located within one of the structural blocks of the Peninsular Ranges of Southern California. The Basin occurs in a linear low-lying block, referred to as the Elsinore-Temecula trough, between the Santa Ana Mountains on the west and the Perris Plain on the east (Norris and Webb 1990). The trough extends from Corona to the southeast some 30 miles and was formed along an extensive northwest-southeast trending fault zone including the Elsinore, Chino, and related faults. The Elsinore faultzone, including the Glen Ivy Fault, bound the Basin on the west and trend along the mountain front.
As shown on Figure 3-5, the oldest rocks in the Study Area crop out in the Santa Ana Mountains. These uplands are composed principally of volcanic (including the Santiago Peak Volcanics) and metamorphic rocks (including the Bedford Canyon Formation) of Jurassic and Cretaceous age. A thin rim of younger sedimentary units of Tertiary age crops out along the mountain front generally lying east of the Glen Ivy Fault within the Elsinore Fault Zone.
Bedford-Coldwater GSP 3-3
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This zone of sedimentary units broadens to the north and contains numerous mapped formations of Cretaceous and Tertiary age. The northeastern side of the valley is flanked primarily by granitic rocks of Cretaceous age. Erosion of these units has filled in the trough over time resulting in quaternary-age alluvial fan, channel, and other deposits making up the permeable portions of the groundwater Basin (Todd and AKM 2008).
The Elsinore Fault Zone forms a complex series of pull-apart basins(Morton and Weber 2003).
The deep portion of the Basin in the Coldwater area is one of these pull-apart basins. Pullapart basins are topographic depressions that form at releasing bends or steps in basement strike-slip fault systems. This initial deposition into the Basin is composed of rapid deposition of landslide and debrisflow deposits which are extremely poorly sorted with a mixture of clay, sand, gravel, and boulders asseen in deep well logs. Since the movement on the faultsisrightlateral, the oldest sediments are located at the lower levels in the northern part of the Basin.
As the pull-apart basin formed, progressively younger sediments have been deposited from north to south. Because of this type of deposition, the lower units of the pull-apart basin can be heterogeneous.
3.5. FAULTS
The Glen Ivy faultzone separatesthe Bedford area from the Coldwater area, having significant impact on the depth of the basin and thickness of alluvial units. The Coldwater area of the Basin is located within a pull-apart basin between the Glen Ivy fault and the Elsinore Fault Zone located at the base of the Santa Ana Mountains. Within the basin, the Glen Ivy faults truncate and offset the alluvial units by up to 250 feet. This offset is inferred from well logs that extend to bedrock near the fault (Todd and AKM 2008 and WEI 2015b).
The Glen Ivy fault limits deep groundwater flow, resulting in a limitation of the hydraulic connection between the Coldwater and Bedford areas. At depth, the offset geologic units place the alluvial deposits in the Coldwater area against the Tertiary Bedford Canyon Formation. When groundwater levels in the Coldwater area are low, there is reduced groundwater flow across the fault. This is especially apparent during the recent periods when the groundwater levels in the Coldwater area were especially low. During these low water periods in the Coldwater area, groundwater levels are higher across the fault in the Bedford area resulting in minor inflows from Bedford into the Coldwater area. This is shown in some recent groundwater level data and supported by the groundwater modeling (Appendix G).
However, at shallower depths, the fault offset is across alluvial deposits. During periods, or areas, when groundwater levels in the Coldwater area are high, groundwater elevation data suggests these areas appear to be well-connected when groundwater elevations in the Basin are high (Todd and AKM 2008), indicating more compartmentalization with depth. However, there isinsufficient groundwater elevation monitoring information to assess the extent of this potential barrier to flow and it is therefore not considered a complete barrier to groundwater flow in the Basin.
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3.6. PRINCIPAL AQUIFER
The following is a summary of the principal aquifer in the Basin, including the source and character of the sediments, lateral boundaries, and faults that potentially affect groundwater flow through the principal aquifer.
3.6.1. Description of Principal Aquifer
The principal aquifer of the Bedford-Coldwater Basin is composed of alluvium, including alluvial fan, alluvial valley, axial channel, and wash deposits. These deposits are sourced from the Santa Ana Mountains to the west of the Basin and the Peninsular Ranges to the east of the Basin. The Bedford Canyon Formation (a slightly metamorphosed sedimentary formation composed of interlayered argillite, slate, graywacke, conglomeratic graywacke, impure quartzite, and small masses of limestone and quartz-rich metasandstone) and adjacent granitic rocks are the primary source materials for these alluvial deposits. The alluvial fan deposits in the Coldwater area extend into the Bedford area and appear to have been disrupted by faulting (Figure 3-5). Channel deposits along Temescal Wash and local tributaries define the eastern boundary of the Basin. In the northern Bedford area, a variety of Tertiary sedimentary units crop outincluding the Silverado (Paleocene), Vaqueros(Miocene), Topanga (Miocene), and Puente (Miocene) formations (Figure 3-5). The alluvial aquifer materials in this portion of the Basin are sourced from these Tertiary sedimentary units. Assuch, the character of the deposits and the groundwater chemistry differ from the alluvial fans in the Coldwater area and those to the north in the Temescal Subbasin and south in the Elsinore Groundwater Basin.
Both older and recent alluvial fans have been deposited along the mountain front on the western edge of the Basin. These fans have prograded across both the Coldwater and Bedford areas from west to east. Although these deposits are relatively thick, the entire unit is heterogeneous. Sand lenses within the fan deposits collectively form the Alluvial Fan Aquifers.
These aquifers from less than 40 feet up to 500 feet in the Bedford area (eastern portion of the Basin) and up to 800 feet in thickness in the deepest portions of the Coldwater area (western portion of the Basin) (Todd and AKM 2008).
3.6.2. Description of Lateral Boundaries
The bedrock units of the uplands provide distinct lateral boundaries for the basin and its alluvial units. Basin alluvium is thin in some areas, which in itself impedes groundwater flow.
This is especially relevant at the northern and southern boundaries of the Basin.
3.7. DEFINABLE BASIN BOTTOM
The Basin bottom is defined by bedrock, which is shallow around the perimeter and deep in the center. Depth to bedrock ranges in depth from 10 feet to over 700 feet (Todd and AKM 2008 and WEI 2015b). The depth to the bottom of the alluvial materials in the Basin and the contact with the bedrock bottom of the Basin are shown in the contours presented in Figure Bedford-Coldwater GSP 3-5
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3-6. Aquifer thickness is greatest in the Coldwater portion of the Basin west of the Glen Ivy fault, as shown in Figures 3-6 and 3-8.
3.8. CROSS SECTIONS
Figure 3-7 is a map showing locations of two cross sections, Figures 3-8 and 3-9. The two hydrogeologic cross sections were constructed to identify hydrogeologic structures affecting groundwater, to characterize the thickness and distribution of aquifer sediments within the Basin, and to confirm aquifer descriptions presented above.
The crosssections and depth to bedrock map were prepared using available information from existing datasets and sources including the following:
• Surficial geology in geographic information system (GIS) coverage format (USGS 2004 and 2006).
• Fault locations and orientations (USGS 2004 and 2006). • Lithologic and well construction logs from local agencies. • Drillers Log files from California Department of Water Resources (DWR). • National Elevation Dataset (NED) ground surface digital elevation model data for Riverside County (USGS 2019).
The two cross sections (Figures 3-8 and 3-9) show the bedrock profile, location of faults, nature and maximum thickness of the alluvial fan aquifers and the relationship with the Temescal Wash deposits. Locations and general construction of wells also are shown. As indicated, alluvialsediments are more than 800 feet thick in the Coldwater area and up to 500 feet thick in the Bedford area, with the thickest section occurring near the Glen Ivy Fault. The crosssections are consistent with and support the conceptual model described above and the depth to bedrock (Figure 3-6).
3.9. STRUCTURES AFFECTING GROUNDWATER
The Basin is defined by the lateral extents of the alluvial material in the pull-apart basin described above. This material is bounded by bedrock in the Santa Ana Mountains on the west and the Peninsular Ranges to the east. The southern and northern boundaries of the Basin are formed by areas of thin alluvial material overshallow bedrock in narrow valleys (Todd and AKM 2008 and WEI 2015b). Within the Basin the groundwater is affected by faulting in the Elsinore Fault Zone, primarily the Glen Ivy fault as described in Section 3.5 above.
3.10. RECHARGE AND DISCHARGE AREAS
Areas of major recharge and discharge are shown in Figure 3-10. Recharge to the Basin occurs primarily from infiltration of runoff, and to a lesser extent from deep percolation of precipitation and urban return flows, wastewater recharge, and subsurface inflow from outside the Basin.
Bedford-Coldwater GSP 3-6
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Most of the Basin recharge comes from the infiltration of runoff from precipitation in the Santa Ana Mountains west of the Basin and the Peninsular Ranges east of the Basin. Large amounts of runoff from the mountains flow into unlined channels and the shallow subsurface at the edges of the Basin and then on into and through the Basin. The amount of water available forrecharge varies annually with changesin rainfall and runoff. Runoff into the Basin is subject to evapotranspiration, infiltration, and continued surface flow to and in the Temescal Wash. The watersheds contributing to the Basin include multiple drainages, all of which flow across the Basin in generally east-west orientations. Wet years generate large amounts of water that exceed the recharge capacity of the Basin (Todd and AKM 2008).
Deep percolation of precipitation is the process by which precipitation enters groundwater.
Recharge to groundwater from deep percolation occurs throughout the Basin (Todd and AKM 2008).
Return flows are those portions of applied water (e.g., landscape irrigation) that are not consumed by evapotranspiration and returned to the groundwater system through deep percolation or infiltration. Return flows associated with urban, industrial, and agricultural water uses all have the potential to contribute to recharge to the Basin (Todd and AKM 2008).
Recharge associated with wastewater occurs with discharges from the wastewater treatment facilities within and upstream from the Basin (TVWD water reclamation facility [WRF] and Corona WRF-3, and Horsethief Canyon WRF, respectively; see Figure 4-14 for locations) and from on-site wastewater treatment systems (OWTS). Subsurface inflow occurs along the Basin boundaries both through bedrock inflow along the western and eastern Basin boundaries and from the Elsinore Subbasin to the south, but these are not considered to be a significant source of recharge to the Basin (Todd and AKM 2008).
Discharge from the Basin is almost entirely from groundwater pumping (see well locations on Figure 3-1), evapotranspiration, and mining operations (quarries on Figure 3-10). There is some limited discharge across the northern Basin boundary with the Temescal Subbasin of the Upper Santa Ana River Basin, but the thin alluvial material in this area limits the volume and timing of subsurface outflow along this boundary (Todd and AKM 2008 and Appendix G).
3.11. PRIMARY GROUNDWATER USES
The primary groundwater uses in the Basin are municipal pumping, with limited private pumping for small water system, commercial, and residential users. Groundwater use estimates are included in Section 5, Water Budget.
3.11.1. Bedford Area
Groundwater in the principal aquifer in the Bedford area is primarily used for non-potable municipal and irrigation water supply. There are no known potable water supply wells in the Bedford area.
Bedford-Coldwater GSP 3-7
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3.11.2. Coldwater Area
The principal aquifer in the Coldwater area is mostly used for municipal water supply. Most of the pumping in this area is from wells owned and operated by the BCGSA agencies, with some additional pumping by small community water system and small commercial users.
Non-potable pumping has occurred historically in this area to support agricultural, recreational, small residential, and industrial water uses.
3.12. DATA GAPS IN THE HYDROGEOLOGIC CONCEPTUAL MODEL
The hydrogeologic conceptual model has not identified data gapsin available information that affect the assessment of sustainability in the Basin.
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Path: T:\Projects\Bedford Coldwater GSP 80802\GIS\Maps\Figures\GSP Figures\Chapter 3 - HCM\Figure 3-2 Tributary Surface Water.mxd Temescal Canyon Road
Cajalco Road
Temescal Canyon Road
Trilogy Parkway
Temescal Canyon Road
Lee
Lake
Mayhew Creek
Coldwater Canyon Creek
Bixby Canyon
Brown Canyon
Anderson Canyon
McBride Creek
Dawson Canyon
Olsen Canyon
Cajalco Canyon
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Te
m
e
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alWash
Bedford Wash
Major Streams
Minor Streams
Bedford-Coldwater Basin
Lake or Pond
Reservoir
Tributary Watershed Boundaries ("N 0 1,750 3,500
Scale in Feet
Figure 3-2
Surface Water Bodies
Tributary to Basin
3-9
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Temescal Canyon Road
Cajalco Road
Temescal Canyon Road
Trilogy Parkway
Temescal Canyon Road
Coldwater Subwatershed
of Lake Mathews Watershed
Temescal
Subwatershed
of Middle
Santa Ana
River
Watershed
Lee Lake Subwatershed
of Lake Mathews Watershed
Bedford Subwatershed
of Lake Mathews Watershed
Bedford-Coldwater Basin
Tributary Subwatershed Boundaries ("N 0 1,750 3,500
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Figure 3-3
Subwatersheds
Tributary to Basin
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Temescal Canyon Road
Cajalco Road
Temescal Canyon Road
Trilogy Parkway
Temescal Canyon Road
Soil Hydrologic Group
A: High Infiltration Rate
B: Moderate Infiltration Rate
C: Slow Infiltration Rate
D: Very Slow Infiltration Rate
No Data
Bedford-Coldwater Basin
Source:
Natural Resources Conservation Service (NRCS), 2019,
SSURGO soil survey online map database available at
http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx last accessed September 2019.
("N
0 1,750 3,500
Scale in Feet
Figure 3-4
Basin Soil
Hydrologic Properties
3-11
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Temescal Canyon Road
Cajalco Road
Temescal Canyon Road
Trilogy Parkway
Temescal Canyon Road
Glen Ivy Fault (Elsinore Fault Zone)
Glen Ivy Fault (Elsinore Fault Zone)
Elsinore Fault Zone
Santa Ana Mountains Qvof
Qvof
Qvof
Qvof
Khg
Qvof1
Kcg
Kvem
Qya
Kcg
Qaf
Kgu
Qyf
Qvof
Qof Kvsp Kgb
Qof
Qof
Qaf
Kcg
Kvsp
Tp
Qof
Qaf
Tp
Tt
Trmu
Jbc
Qvof
Kvsp
Tlm?
Kcto
Qvof
Kcg
Qvoa
Qvof
Tlm
Tlm
Qvof
Tt
Kvem
Kgb
Qya
Kvs
Tsi
Qaf
Qvof
Qyf
Trmu
Qya
Qaf
Trmu
Qaf
Qyf
Qof
Tsi
Trms
Qaf
Qvof
Kcg
Kcg
Qaf
Qof
Qvoa
Kvem
Qaf
Tp
Trmu
Tf
Tsi
Tsi
Qaf
Tf
Qvoa
Qvof
Kcgb
Kcgb
Tlm
Tvs
Tf
Trmu
Qvof
Qaf
Kvsp
Qaf
Tvs
Qof
Qoa
Qvoa
Tsi
Qvof
Kcg
Khg
Tf
Qvof
Qols
Tf
Tsi
Qoa
Qyf
Tsi
Qvof
Qvof
Qaf
Qvoa
Tlm
Tf Qvof
QTn
Qols
Qvof
Kcg
Qyf
Qvof
Tf Tf
Qols
Kcto Kcto
Qaf
Qyls
Tsi
Qols
Tf
Tp
Tlm
Qyls
Qvof
Tp
Qyf
Qvof
Qof
Tsi
Tp
Tt
Kcg
Qols
Qvof
Qvof
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Tt
Qvof
Qof
Kcg
Tvs
Qvof
Qvof
Qyf
Qvof
Tsi
Qyf
Qyls
Tlm
Qvof
Tlm
Qvof
Tsi
Tvs
Qyls
Tlm
Tvs
Kvem
Tlm
Tvs
Qyls
Qvof
Qaf
Tvs
Tlm
Tlm
Qvof
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Tsi Qvof
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Qvoa
Qyf
Tsi
Tsi
Qyf
Khg
Qof
Qvof
Qvof
Tsi
Qvof
Qvof
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Qyls
Khg
Tsi
Qvof
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Tvs
Tsi
Qaf
Qvof
Tsi
Qvof
Qaf
Qvof Qvof
Qvof
Qvof
Qaf
Trmu
Qvof
QTt
Kvem
Tsi
Tsi
Qyf
Qyf
Tsi
Qyf
Qvof
Qvof
Tsi
Qof
Qvof
Qyv
Qvof1
Kvspi
Trmu
Qvof1
Qvof
Qyf
Kvspi
Qvof1
Qvof1
Tsi
Kvspi
Jbcm
Tsi
Qyf
Kvspi
Qof
Tsi
Qvof
Jbcm
Qyv
Qvof1
Kgt
Tsi
Qvof1
Qvof
Qvof
Qaf
Qyf
Qyf
Qvof1
Qvof1
Khg
Trmu
Qvof
Qyf
Qyf
Qvof
Kvspi
Trmu
Qyf
Qvof
Qvof
Qvof
Tsi
Qvof
Kvspi
Qvof
Kvem
Kvspi
Qyf
Qyf
Qvof
Qov
Qyf
Jbc
Qof
Qvof Qvof1
Qof
Qov
Qyf
Qvof
Qvof Khg
Qvof
Kvspi
Qvof1
Qvof
Kvspi
Qyf
Qof
Kvem
Kvspi
Kvspi
Kvem
Qya
Qyf
Qof
Qyf
Qyf
Qyf
Kvem
Kvspi
Qvof
Qof
Qvof
Qyf
Qvof
Tsi
Kvspi
Qoa
Qyf
Khg
Qof
Qyf
Qvof
Qvoa
Ql
Ql
Qaf
Qf
Qya
Qya
Qvof
Qvof
Qyf
Qof
Qf
Jbc
Kgu
Qyls
Qyls
Qvoa
Qof
Qvof
Kgu
Khg
Jbc
Jbc
Qyf
Jbc
Jbc
Jbc
Jbc
Kgu
Qof
Qya
Qya
Kgu
Qyf
Kgu
Qoa
Qyls
Jbc
Qw
Qyf
Qof
Kgu
Qof
Jbc
Kgu
Qyf
Jbc
Qw
Qyls Qyls
Qyls
Qyls
Qyls
Qyls
Qyls
Qyls
Qvoa
Qyls
Qvoa
Qvoa
Qyls
Qyls
Qyls
Qyls
Qyls Qyls
Bedford-Coldwater Basin
Fault Location, dashed where uncertain
Qaf, Artificial fill
Qw, Very young wash deposits
Qf, Very young alluvial-fan deposits
!
!
!
!! !
!
! !
!
!
!
Ql, Very young lacustrine deposits
! Qyw, Young wash deposits
Qyf/Qyf1, Young alluvial-fan deposits
! ! !
! !
!
!
!
! !
!
! !
!
!
!
! ! !
!
! !
Qya, Young axial-channel deposits
Qyv, Young alluvial-valley deposits
Qyls, Young landslide deposits
Qof, Old alluvial-fan deposits
Qoa, Old axial-channel deposits
Qov, Old alluvial-valley deposits
Qols, Old landslide deposits
Qvof, Very old alluvial-fan deposits
Qvoa, Very old axial-channel deposits
QTt, Conglomerate of Temescal area
!
!
!!
!! !
!
QTn, Sedimentary rocks of Norco area
Tf, Fernando Formation
Tp, Puente Formation
Tlm, Lake Mathews Formation
Tcgr, Rhyolite-clast conglomerate of Lake Mathews area
Tt, Topanga Group
Tvs/Tvss, Vaqueros and Sespe Formations, undifferentiated Tsi, Silverado Formation
Kgg/Kgt/Kgtf/Kgti/Kgh/Kgh/Kght, Gavilan Ring Complex
Katg, Granodiorite of Arroyo del Toro Pluton
Kcto/Kcg/Kcgd/Kct/Kcgq/Kcgb, Cajalco Pluton
Kgu, Granite, undifferentiated
Kgb, Gabbro, undifferentiated
Khg, Heterogeneous granitic rocks
Kvsp/Kvspi, Santiago Peak Volcanics
Kvem/Kvr/Ksv/Kvs, Estelle Mountain volcanics of Herzig
Jbc/Jbcm, Bedford Canyon Formation
Trms/Trmu, Rocks of Menifee Valley
Source:
United States Geological Survey (USGS), 2004,
Preliminary Digital Geologic Map of the Santa Ana 30’ x 60’ Quadrangle, Southern California, Version 2.0 compiled by D.M. Morton, Open-File Report 99-172,
http://pubs.usgs.gov/of/1999/of99-172/
and
United States Geological Survey (USGS), 2006,
Geologic Map of the San Bernardino and Santa Ana 30’ x 60’ Quadrangles, California, Version 1.0 compiled by
Douglas M. Morton and Fred K. Miller, Open-File Report
2006-1217, http://pubs.usgs.gov/of/2006/1217/
(
"N
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Scale in Feet
Figure 3-5
Surficial Geology
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Temescal Canyon Road
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Glen Ivy Fault (Elsinore Fault Zone)
Glen Ivy Fault (Elsinore Fault Zone)
Elsinore Fault Zone
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Service Layer Credits: Esri, HERE, Garmin,
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40-foot Depth to Bedrock Contour, dashed where
uncertain due to insufficient data
Fault Location, dashed where uncertain
Bedford-Coldwater Basin
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Figure 3-6
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A! Wells on Cross Sections
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Scale in Feet
Figure 3-7
Cross Section
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Inferred Glen Ivy Fault Splay
North Glen Ivy Fault
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Santa Ana
Mountains105257
103864
479116
516080 (Corona #20)
50847
051146
328127
157226
Granitic
Bedrock
Glen Ivy Fault
Granitic
Bedrock
Alluvial Fan
Aquifer
Alluvial Fan
Aquifer
Temescal
Wash
Granitic
Bedrock
Coldwater Area Bedford Area
A’
East
A
West
Elevation, feet msl
Elevation, feet msl
2000 4000 6000 8000 10000 12000 14000 16000
?
?
?
Water Level
Groundwater Elevation
(dashed where estimated)
Figure 3-8
Cross Section
A to A’
LEGEND
DWR Well Number
5X Vertical Exaggeration
Alluvial Fan Aquifer
Granitic Bedrock Well Screen
Bottom of Well
50847
3-15
103782 516083 516080 5/6-11K1218077 36354
Feet
Water Level
Groundwater Elevation
(dashed where estimated)
Figure 3-9
Cross Section
B to B’
LEGEND
DWR Well Number
Well Screen
Bottom of Well
36354
0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 -200
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600
800
1000
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0 200
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Aquifer
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Aquifer
Granitic
Bedrock
Granitic
Bedrock
B’
South
B
North
Elevation, feet mslElevation, feet msl
Unnamed Fault
103872
516083 (Corona #21)
Corona # 1
Corona # 2
516080 (Corona # 20)
5/6-11K1
218077
36354
Coldwater Area
5X Vertical Exaggeration
Alluvial Fan Aquifer
Granitic Bedrock
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escal
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Lake or Pond
Major Streams
Minor Streams
Urban Recharge
Irrigated Area Recharge
Unirrigated Area Recharge
Quarries ("N 0 1,750 3,500
Scale in Feet
Figure 3-10
Groundwater Recharge
and Discharge
3-17
Bedford-Coldwater GSP 4-1
TODD GROUNDWATER,
H&H Water Resources,
and Stantec
4. CURRENT AND HISTORICAL GROUNDWATER CONDITIONS
The Sustainable Groundwater Management Act (SGMA) requires definition of various study periods for current, historical, and projected future conditions. Current conditions, by SGMA definition, include those occurring after January 1, 2015 and accordingly, historical conditions occurred before that date. A historical period must include at least 10 years.
The study period 1990 through 2018 is based on the cumulative departure from mean precipitation at Santiago Peak, Lake Elsinore, and Riverside climate monitoring stations. This period is representative and includes droughts and wet years, with an average annual rainfall of 12.97 inches, comparable to the long-term average of 12.9 inches (1875 to 2017).
Accordingly, groundwater conditions over time are described through 2018.
Groundwater conditions are described in terms of the six sustainability indicators identified in SGMA; these include:
• Groundwater elevations.
• Groundwater storage.
• Potential subsidence.
• Groundwater quality.
• Seawater intrusion (which is not likely to occur in this inland basin). • Interconnected surface water and groundwater dependent ecosystems.
4.1. GROUNDWATER ELEVATIONS
4.1.1. Available Data
Groundwater elevation records were collected from multiple sources, including previous investigations, City of Corona, United States Geological Survey (USGS) National Water Information System (NWIS), California Department of Water Resources (DWR), and California Statewide Groundwater Elevations Monitoring (CASGEM). Data from these sources were collected, reviewed, and compiled into a single unified groundwater elevation dataset. The wells with water level measurement records are shown on Figure 4-1.
4.1.2. Groundwater Occurrence
As summarized in Chapter 3, groundwater is present in one principal aquifer. Groundwater in the Bedford-Coldwater Subbasin (Basin) occurs under unconfined conditions and there are no data to suggest distinct vertical zones or to provide zone-specific groundwater elevation hydrographs or maps.
4.1.3. Groundwater Elevations and Trends
Hydrographs showing groundwater elevation trends over time were prepared for all 28 wells with elevation data in the Basin; these hydrographs then were reviewed to identify wells with Bedford-Coldwater GSP 4-2
TODD GROUNDWATER,
H&H Water Resources,
and Stantec
long term data that could be used to present representative hydrographs. The selection of representative wells was based on a quantitative approach that considered hydrographs with long records characteristic of an area and distribution of wells across the Basin. All available groundwater elevation data were plotted as hydrographs and well locations were plotted on a basin-scale map. All wells with water level data are shown in Figure 4-1. Long term changes in groundwater elevations in the Basin are illustrated in representative hydrographs shown in Figures 4-2 through 4-6 and show conditions since January 1990, where available, thus showing the study period for the Groundwater Sustainability Plan (GSP).
Representative wells with long term hydrographs were selected based the following criteria:
• Location – Wells were prioritized considering broad distribution across the Basin and availability of other wells nearby.
• Ongoing and/or recent monitoring – Wells were selected that are part of the active monitoring network or have recent data.
• Trends – Each hydrograph was assessed for continuity of monitoring, representation of local or regional trends, and presence of outliers or unrealistic data.
The northern hydrograph wells in Figure 4-2 through 4-5 all reflect stable groundwater level conditions. These four wells show a slight decrease during the 2013 through 2015 drought but the net change is only 20 to 30 feet. The southernmost well, Corona 3 on Figure 4-6 shows conditions in the Coldwater area where there is more variation than other areas of the Basin.
Asshown on the hydrograph, water levels have declined over the last 24 years with significant fluctuations in response to wet and dry cycles. Water levels in the Coldwater area have varied more than 350 feet over the last 30 years with multiple major and minor cycles of groundwater elevation decline and recovery, as illustrated on the hydrograph. Some of the short-term fluctuations may have been influenced by incomplete recovery of pumping water levels in the well. The wide water level fluctuations over time in the Coldwater area likely reflect the relatively small footprint and fault-controlled flow along with the fact that most of the pumping in the Basin occurs in this area. Although long-term declines in groundwater elevations have occurred in Coldwater in the past, recent groundwater elevations have stabilized due in part to shared management of the Basin between the three BedfordColdwater Groundwater Sustainability Agency (BCGSA) agencies.
Recent water levels in the Coldwater area are just below 800 feet msl (as shown on Figure 4- 6) and reflect a recovery of approximately 60 feet from the historical low reached in late 2010.
This recovery is due, in part, to a production agreement between the City of Corona (Corona) and Elsinore Valley Municipal Water District (EVMWD) for the Coldwater portion of the Basin, where most of the pumping occurs.
4.1.4. Groundwater Flow
Figures 4-7 and 4-8 are groundwater elevation contour maps constructed to examine current groundwater flow conditions and using data from fall 2015 and spring 2018, respectively.
Contours were developed based on available groundwater elevation data for all wells and information from the numerical groundwater model (Appendix G). The fall 2015 groundwater Bedford-Coldwater GSP 4-3
TODD GROUNDWATER,
H&H Water Resources,
and Stantec
elevation contours (Figure 4-7) show flow generally from south to north in the Basin and from the northwest to the northeast in the north of the Basin. A slight water table depression occurs in the Coldwater area around the active production wells. Water levels in the Bedford area near the Glen Ivy fault were higher than those across the fault in the Coldwater area, indicating flow from Bedford to Coldwater. The groundwater elevations in this period represent relatively dry conditions at the end of the most recent drought period. Spring 2018 groundwater elevation contours (Figure 4-8) also show flow generally south to north with easterly flow in the north of the Basin and a small depression in the Coldwater area. Spring 2018 followed a period of relatively wet conditions. However, water levels in the Basin were very similar to those during the fall 2015 dry conditions. This includes the depression in the Coldwater area and the indication of flow from Bedford to Coldwater acrossthe Glen Ivy Fault.
Both fall 2015 and spring 2018 contours show that groundwater elevations are relatively consistent.
4.1.5. Vertical Groundwater Gradients
The current monitoring network for groundwater elevations provides little information about vertical head (groundwater elevation) gradients within the Basin. Available data are almost entirely from water supply wells, which are typically screened between 200 and 500 feet below ground surface (bgs). The potentiometric head at the depth of the well screens can be different from the true water table, which is the first zone ofsaturation reached when drilling down from the ground surface.
4.2. CHANGES IN GROUNDWATER STORAGE
Change in storage estimates based on evaluation of groundwater elevation changes and water budget inflow and outflow have completed for the portions of the Basin in past studies (MWH 2004, SAIC 2007, WEI 2015a, 2015b, 2016, 2017b, and 2019). Such storage change estimates are based on available groundwater elevation data that are limited geographically and temporally and thusinclude uncertainty. In addition, the storativity, orstorage coefficient (the volume of water released from storage per unit decline in hydraulic head), is largely unknown across the Basin. The volume of groundwater storage change over time can be calculated by multiplying the groundwater elevation changes during a period by the storage coefficient. Storage coefficient value and storage change estimates for the Basin have been developed through calibration of the numerical model, as described in Appendix G.
Therefore, the numerical model is the best tool for estimating groundwater storage changes.
The resulting change in storage estimates are presented in the Water Budget chapter.
4.3. LAND SUBSIDENCE AND POTENTIAL FOR SUBSIDENCE
Land subsidence is the differential lowering of the ground surface, which can damage structures and facilities. This may be caused by regional tectonism or by declines in groundwater elevations due to pumping. The latter process is relevant to the GSP. While subsidence has not been a known issue in the Basin, groundwater elevation declines in the Bedford-Coldwater GSP 4-4
TODD GROUNDWATER,
H&H Water Resources,
and Stantec
subsurface, resulting in dewatering and compaction of predominantly fine-grained deposits (such as clay and silt) can cause the overlying ground surface to subside.
This process is illustrated by two conceptual diagrams shown on Figure 4-9. The upper diagram depicts an alluvial groundwater basin with a regional clay layer and numeroussmaller discontinuous clay layers. Groundwater elevation declines associated with pumping cause a decrease in water pressure in the pore space (pore pressure) of the aquifer system. Because the water pressure in the pores helps support the weight of the overlying aquifer, the pore pressure decrease causes more weight of the overlying aquifer to be transferred to the grains within the structure of the sediment layer. If the weight borne by the sediment grains exceeds the structural strength of the sediment layer, then the aquifer system begins to deform. This deformation consists of re-arrangement and compaction of fine-grained units2 , as illustrated
on the lower diagram of Figure 4-9. The tabular nature of the fine-grained sediments allows for preferred alignment and compaction. As the sediments compact, the ground surface can sink, as illustrated by the right-hand column on the lower diagram of Figure 4-9.
Land subsidence due to groundwater withdrawals can be temporary (elastic) or permanent (inelastic). Elastic deformation occurs when sediments compress as pore pressures decrease but expand by an equal amount as pore pressures increase. A decrease in groundwater elevations from groundwater pumping causes a small elastic compaction in both coarse-and fine-grained sediments; however, this compaction recovers as the effective stress returns to its initial value. Because elastic deformation is relatively minor and fully recoverable, it is not considered an impact.
Inelastic deformation occurs when the magnitude of the greatest pressure that has acted on the clay layer since its deposition (preconsolidation stress) is exceeded. This occurs when groundwater elevations in the aquifer reach a historically low groundwater elevation. During inelastic deformation, or compaction, the sediment grains rearrange into a tighter configuration as pore pressures are reduced. This causes the volume of the sediment layer to reduce, which causesthe land surface to subside. Inelastic deformation is permanent because it does not recover as pore pressures increase. Clay particles are often planar in form and more subject to permanent realignment (and inelastic subsidence). In general, coarse-grained deposits (e.g., sand and gravels) have sufficient intergranular strength and do not undergo inelastic deformation within the range of pore pressure changes encountered from groundwater pumping. The volume of compaction is equal to the volume of groundwaterthat is expelled from the pore space, resulting in a loss of storage capacity. This loss of storage capacity is permanent but may not be substantial because clay layers do not typically store significant amounts of usable groundwater. Inelastic compaction, however, may decrease the vertical permeability of the clay resulting in minor changes in vertical flow. 2 Although extraction of groundwater by pumping wells causes a more complex deformation of the aquifer system than discussed herein, the simplistic concept of vertical compaction is often used to illustrate the land subsidence process (LSCE et al. 2014).
Bedford-Coldwater GSP 4-5
TODD GROUNDWATER,
H&H Water Resources,
and Stantec
The following potential impacts can be associated with land subsidence due to groundwater withdrawals (modified from LSCE et al. 2014):
• Damage to infrastructure including foundations, roads, bridges, or pipelines, • Loss of conveyance in canals, streams, or channels,
• Diminished effectiveness of levees,
• Collapsed or damaged well casings, and
• Land fissures.
4.3.1. Interferometric Synthetic Aperture Radar (InSAR) InSAR data are provided by DWR on its SGMA Data Viewer (DWR 2020) and document vertical displacement of the land surface across a broad area of California from June 13, 2015 to September 19, 2019. The accuracy of the InSAR ground surface elevation change estimates is reported to be ±16 millimeters (mm), or ±0.052 feet (ft) (Towill 2020). The TRE Altamira InSAR Dataset, shown on Figure 4-10 shows mapping within the Basin for land surface deformation between 2015 and 2019.
The TRE Altamira InSAR data on Figure 4-10 uses a range of 0.05 to -0.05 ft to display the estimated ground surface elevation change in the Basin. The maximum estimated ground surface elevation rise in the Basin between 2015 and 2019 is 0.02 ft and the maximum decline is -0.05 ft. These estimated changes are lessthan the reported accuracy forInSAR. Thus, based on the InSAR estimates there has effectively been no change in ground surface elevation within the Basin in the 2015 to 2019 period. Given these data and the understanding of the hydrogeological conceptual model, there is no evidence of subsidence at this time.
4.4. GROUNDWATER QUALITY
The natural quality (chemistry) of groundwater is generally controlled by the interaction between rainwater and rocks/soil of the vadose zone and aquifers (Drever 1988). As rainfall infiltrates through the soil column, changes in water chemistry occur as anions and cations are dissolved into the water. These changes are influenced by soil and rock types, weathering, organic matter, and geochemical processes occurring in the subsurface. Once in the groundwater system, changing geochemical environments continue to alter groundwater quality. A long contact time between the water and sediments may allow for more dissolution and more concentrated groundwater (Drever 1988). The natural groundwater quality in a basin is the net result of these complex subsurface processes that have occurred over time.
General mineral quality of groundwater is naturally poor, especially in the Bedford area, as indicated by relatively high concentrations of total dissolved solids and sulfate. This reflects in part the occurrence in the northern Bedford area of Tertiary sedimentary units, in contrast to the alluvial fans of the Coldwater area. The Corona Groundwater Management Plan evaluated the geochemistry of the Basin, and compared the Coldwater area to the Bedford area (Todd and AKM 2008). This evaluation showed the Coldwater area had a relatively high calcium-to-sodium ratio compared to groundwater in the Bedford area and downgradient Bedford-Coldwater GSP 4-6
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Temescal Basin. This relationship showed a difference in the source material in the aquifer in these two locations. The aquifer material in the Coldwater area is sourced from the granitic units in the Santa Ana Mountains, while the material in the Bedford area is sourced from the Tertiary sedimentary units that outcrop within that area and east of the Basin.
Groundwater quality can vary in the Basin; some areas have good water quality while other areas have high mineral concentrations, generally presenting as elevated total dissolved solids (TDS). High TDS concentration in groundwater can be naturally occurring and also the result of anthropogenic sources such as urban runoff, historical agricultural activities, and treated wastewater discharge. Nitrate was historically elevated in parts of the Basin, but recent concentrations have been relatively low. Natural nitrate levels in groundwater are generally very low, and elevated concentrations are associated with agricultural activities, septic systems, landscape fertilization, and wastewater treatment facility discharges.
Groundwater in the Basin has been impacted by human activities including agricultural, urban, and industrial land uses. State agencies with regulatory oversight for water quality in the Basin include the Santa Ana Regional Water Quality Control Board (RWQCB) and the State Water Resources Control Board (SWRCB) – Division of Drinking Water (DDW).
4.4.1. Monitoring Networks
State Water Board GAMA Program
The State Water Board Groundwater Ambient Monitoring and Assessment (GAMA) Program (SWRCB 2019) is the primary source of groundwater quality data in the Basin. The GAMA program has water quality data from 27 wells. Only six of these wells have recent water quality data (data collected since January 2015).
Division of Drinking Water (DDW)
There are four drinking water systems (Corona, EVMWD, Temescal Valley Water District [TVWD], and Glen Ivy Golf Club), with a total of eight well locationsin the Basin. These stations report water quality data to the DDW. Each system monitors and reports water quality parameters to DDW and is required to participate in the Drinking Water Source Water Assessment Program (DWSAP) to ensure wells are not subject to local contamination.
Other Agencies
The RWQCB regulates one site in the Basin, Villa Park Trucking. Groundwater quality data were collected from one well on site from 1997 to 2007. In addition, DWR monitored 17 wells in the Basin from 1955 to 1988 and the USGS monitored two wells from 2006 to 2011.
Wells with water quality data from all available sources are shown on Figure 4-11.
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4.5. OTHER STUDIES
4.5.1. Salt and Nutrient Management Plan 2017
The RWQCB manages salinity in the Santa Ana River Basin, in part by regulating the discharge and reuse of recycled water. TDS and nitrate concentration limitations for recycled water discharge and reuse are set by the RWQCB based on the Wasteload Allocation for surface watersin the Santa Ana River Watershed and the antidegradation objectives and ambient TDS and nitrate concentrations of the receiving groundwater management zone (GMZs), as defined in the Water Quality Control Plan for the Santa Ana River Basin (Basin Plan). While there were two GMZs in the Basin (Bedford and Coldwater), Bedford was combined into the Upper Temescal Valley GMZ.
Consistent with the 2013 SWRCB Recycled Water Policy, a Salt and Nutrient Management Plan (SNMP) was developed for the Upper Temescal Valley, including the Bedford area, in 2017 (WEI 2017a). The purpose of the SNMP was to identify sources of salts and nutrients (current and future) as context for assessing potential impacts of recycled water projects and to plan for management of salt and nutrient sources to ensure that groundwater is safe for drinking and all other beneficial uses. Beneficial uses of water and respective water quality objectives are defined by the RWQCB in the Basin Plan. The report found that TDS concentrations were highly variable across space and time, ranging from a low of 240 milligrams per liter (mg/L) to a high of 1,500 mg/L, and there was no significant long-term trend of water quality degradation or improvement. Similar to TDS, nitrate concentrations are also highly variable; however, there does appear to be a decrease in concentrations over time, which is probably due to the reduction in irrigated agriculture land uses and hence a reduction in added nitrogen in the form of fertilizers.
The SNMP recommended TDS and nitrate antidegradation objectives for the Upper Temescal Valley GMZ consistent with the 2004 Basin Plan. These proposed objectives for TDS and Nitrate as N are 820 mg/L and 7.9 mg/L, respectively (WEI 2017a). These objectives (pertinent to Bedford area) are lower (stricter) than drinking water standards.
4.6. THREATS TO WATER QUALITY
4.6.1. Regulated Facilities
The RWQCB regulates one site in the Basin, Villa Park Trucking. Groundwater quality data were collected from one well on site from 1997 to 2007, and the site has since been closed.
4.6.2. Septic Systems
Some limited areas of the Basin are not served by municipal sewer and rely on on-site wastewater treatment (OWTS orseptic systems). These representsources ofsalt and nutrient loading to groundwater, as well as potential sources of other contaminants. Riverside County Department of Environmental Health is the permitting agency for septic systems and wells in Bedford-Coldwater GSP 4-8
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the County. The Riverside County Department of Environmental Health maintains an inventory of septic system installations but does not track which remain active. While it is known how many of these septic systems exist, the number is assumed minimal; most of the BCGSA area is sewered.
4.6.3. Non-point Sources
Nonpoint source (NPS) pollution is defined by the SWRCB as contamination that does not originate from regulated point sources and comesfrom many diffuse sources. NPS could occur when rainfall carries contaminants to surface water ways or percolates contaminants to groundwater. One example relevant to the Basin is loading to groundwater of nitrate from agricultural or landscaping land applications.
4.7. KEY CONSTITUENTS OF CONCERN
TDS and nitrate are the primary indicators for salt and nutrient loading and thus are key constituents of concern (COCs) for Basin management.
TDS data are available for both inflows and outflows from the Basin. There are elevated natural background TDS concentrations in groundwater. In addition, TDS can be an indicator of anthropogenic impacts (e.g., infiltration of urban runoff, agricultural return flows, and wastewater disposal).
Nitrate is the primary form of nitrogen detected in groundwater and natural nitrate levels in groundwater are generally very low. Elevated concentrations of nitrate in groundwater are associated with agricultural activities, septic systems, landscape fertilization, and wastewater treatment facility discharges. The maximum contaminant level (MCL) for nitrate (as nitrogen) is 10 mg/L. Nitrate data are available for Basin inflows and outflows, and as documented in the SNMP (WEI 2017a), elevated nitrate concentrations have been recognized. The SNMP analysis of nitrate loading found that most areas had predicted small increasing trends in nitrate in groundwater. However, no wells exceed the MCL for nitrate.
4.7.1. Key Constituents in Groundwater
TDS and nitrate are the constituents of concern in the Basin. Current average conditions(2010 through 2019)show average recent concentrations of TDS of 674 mg/L and nitrate as nitrogen concentrations of 2.75 mg/L. The values represent the average concentrations of these constituents in all drinking water and ambient groundwater monitoring events between 2010 and 2019; water quality samples from regulated facilities were not included in the analysis.
These average conditions serve as a snapshot and allow a comparison of water quality conditions across the Basin.
4.7.2. Total Dissolved Solids (TDS)
As indicated above, average recent TDS concentrations in the Basin are just below the secondary MCL for drinking water (500 mg/L). Recent maximum TDS concentrations from all Bedford-Coldwater GSP 4-9
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wells are shown on Figure 4-12. While recent concentrations are generally lower than 500 mg/L several historical water quality analyses from wells had higher concentrations of TDS (e.g., exceeding 500 mg/L). Based on data collected by the BCGSA agencies and Glen Ivy (a small water system) from 2010 through 2019, TDS ranges from 210 milligrams per liter (mg/L) to 1,110 mg/L. The recommended TDS secondary maximum contaminant level (SMCL) for aesthetics is 500 mg/L.
4.7.3. Nitrate as Nitrogen (NO3 as N)
The average recent nitrate as nitrogen concentration (2.75 mg/L) is low relative to the MCL of 10 mg/L. Figure 4-13 shows the maximum nitrate as nitrogen concentrations at each well in the Basin. Several wellsin the northern portion of the Basin show elevated historical nitrate concentration of up to 24.8 mg/L. However, no current nitrate detections exceed the MCL of 10 mg/L for nitrate as nitrogen. Nitrate has multiple and widespread sources including fertilizer application (agricultural and landscaping) and wastewater disposal (both municipal and domestic). Given that these sources are on or near the ground surface, shallow groundwater typically is characterized by higher concentrations than deep groundwater.
4.7.4. Other Constituents
In 2021, the BCGSA performed a round of baseline water quality sampling for the GSP. This sampling was designed to serve as a snapshot of ambient water quality for 48 constituents, including perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). Eight wells were sampled, three in Bedford and two in Coldwater; the results of this sampling event are included in Appendix H. PFOS and PFOA were detectable with maximum concentration of 14 nanograms per liter (ng/L) and 25 ng/L respectively. The PFOS concentration is slightly above the response limit of 10 ng/L parts per trillion (ppt) but the PFOA concentration is below the 40 ng/L for PFOS (SWRCB 2020). The response limit for both PFOS and PFOA are based on a running four quarter average, so are not triggered by one sample.
Available water quality data indicate slightly elevated sulfate concentrations in the Basin.
While historical sulfate concentrations ranged from 4 to 339 mg/L, recent samples collected in 2021 show sulfate concentrations from 110 to 270 mg/L. Concentrations in two Bedford wells were above the SMCL for sulfate of 250 mg/L but all wells were below the primary (health related) MCL of 500 mg/L. Sulfate will continue to be monitored as part of the BCGSA’s monitoring program, it was not selected as a constituent of concern. The causes of elevated sulfate may be anthropogenic or naturally occurring. The anthropogenic sources of sulfate are likely from historical agricultural practices that are similar to nitrate and the natural occurrence due to geologic environment are similar to TDS. Therefore, TDS and nitrate are sufficient proxies for sulfate.
Other constituents that could impact beneficial uses or users, including arsenic, were not detected. While recent water quality data are limited, there is no indication of other constituents of concern. The BCGSA will continue to monitor water supply wells for Title 22 constituents to ensure adequate water quality in the Basin.
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4.7.5. Vertical Variations in Water Quality
Water quality monitoring programs in the Basin do not show a distinct difference of water quality in depth, in part because most of the ambient monitoring wells have long screened intervals or are collected from wells with unknown construction.
4.8. SEAWATER INTRUSION CONDITIONS
The Basin is located approximately 25 miles inland from the Pacific Ocean. Lowest elevations (at the northern boundary of the Basin) are above about 1,000 feet. No risk of seawater intrusion exists in the Basin given its location.
4.9. INTERCONNECTION OF SURFACE WATER AND GROUNDWATER
Interconnection of groundwater and surface water occurs wherever the water table intersectsthe land surface and groundwater dischargesinto a stream channel orspring. These stream reaches gain flow from groundwater and are classified as gaining reaches. Conversely, connection can occur along stream reaches where water percolates from the stream into the groundwater system (losing reaches), provided that the regional water table is close enough to the stream bed elevation that the subsurface materials are fully saturated along the flow path.
Groundwater pumping near interconnected surface waterways or springs can decrease surface flow by increasing the rate of percolation from the stream or intercepting groundwater that would have discharged to the stream or spring. If a gaining stream is the natural discharge point for a groundwater basin, pumping anywhere in the basin can potentially decrease the outflow, particularly over long time periods such as multi-year droughts.
Because of the long dry season that characterizes the Mediterranean climate in Riverside County, vegetation exploits any near-surface water sources, including the water table along perennialstream channels,the wetsoil areas around springs, and areas where the watertable is within the rooting depth of the plants. Plants that draw water directly from the water table are called phreatophytes. They are able to continue growing vigorously during the dry season and typically stand out in summer and fall aerial photographs as patches of vegetation that are denser, taller, and brighter green than the adjacent vegetation.
4.9.1. Stream Flow Measurements
Three USGS streamflow gaging stations provide a general characterization of the stream flow regime in Temescal Wash and its tributaries. Their locations are shown in Figure 4-14, and daily flows during water years 2013 through 2020 are shown in Figure 4-15. Temescal Creek at Corona Lake (USGS 11071900) is located at the outlet of Lee Lake at the upstream end of the Basin. Flow at that location is primarily ephemeral, occurring only during and immediately following rainstorm events. No flow was recorded for three consecutive years during the Bedford-Coldwater GSP 4-11
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recent drought. However, the gage also records recycled water discharges from Eastern Municipal Water District (EMWD), which historically have often been large enough to flow down Temescal Wash as far as Lee Lake. Those discharges were more common prior to the period of gaged flows but still occur in wet years when EMWD is unable to use or store all of its recycled water.
The gauge on Coldwater Canyon Creek has only been in operation for one year, and it is the only record of flow in any drainage on the eastern slopes of the Santa Ana Mountains. The flow regime includes high peaks during storm events and small but persistent base flow supported by drainage of groundwater from fractured bedrock in the watershed. These small flows rapidly percolate where the creek enters the Basin and do not reach Temescal Wash.
All of the tributary watersheds on the west side of the Basin likely have similar flow regimes.
The gauge above Main Street in Corona experiences many more peak flow events. Most of these additional flow events probably derive from imperviousrunoff in the surrounding urban area. A steady base flow of about 2 cubic feet per second (cfs) is not groundwater discharge, but so-called nuisance water (for example,sprinkler overspray onto paving, or pipe leaks) plus discharge from the wastewater treatment plant upstream of the gauge.
A review of 27 high-resolution aerial photographs (Google Earth 2021) between 1994 and 2020 did not reveal any reaches of Temescal wash that appeared to have groundwater discharge; that is, flowing or ponded reaches in an otherwise dry channel during the dry season. Thus, the reach of Temescal Wash that passes through the Bedford-Coldwater Basin does not appear to gain flow from groundwater seepage into the channel, at least during the dry season. Water levels in wells near the creek further suggest that the water table is usually below the creek bed elevation. Data showing depth to the water table are discussed in the next section.
4.9.2. Depth to Groundwater
Depth to groundwater provides a general indication of locations where gaining streams and riparian vegetation are likely to be present. However, available data are of limited use for this purpose due to insufficient geographic and vertical coverage. Available data are almost entirely from water supply wells, which are typically screened deep in the aquifer. The groundwater elevation (potentiometric head) at the depth of the well screen can be different from the true water table, which is the first zone of saturation reached when drilling down from the ground surface. Because recharge occurs at the land surface and pumping occurs at depth, deep alluvial basins such as this one typically have large downward head gradients within the aquifer system. Thus, water level information from wells can potentially underestimate the locations where the water table is shallow enough to support phreatophytic riparian vegetation.
Creeks and rivers that lose water commonly form a mound in the water table near the creek or river. The height and width of the mound depends on the transmissivity of the shallowest aquifer. As an example, in other basins where this condition is observed, groundwater elevations in a shallow well adjacent to the Arroyo Seco in the Salinas Valley California rose 5 to 10 feet more than groundwater elevations in wells 1,000 feet away when the river started Bedford-Coldwater GSP 4-12
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flowing (Feeney 1994). A groundwater ridge up to 12 feet high develops beneath Putah Creek in Yolo County California during the flow season, but the width of this ridge was estimated to be only a few hundred feet (Thomasson et al. 1960). These examples suggest that shallow wells within 100 to 200 feet of a stream channel would be needed to confirm the presence of hydraulic connection between surface water and groundwater in the Bedford-Coldwater Basin.
Groundwater does not discharge into streams unlessthe watertable is equal to or higherthan the elevation of the stream bed. In addition, the water table does not provide water to phreatophytic vegetation unless it is at least as high as the base of the root zone. The depth of the root zone is uncertain, partly because the relatively few studies of rooting depth have produced inconsistent results and partly because rooting depth for some riparian species is facultative. Thismeansthatthe plants will grow deeperrootsif the watertable declines. Many species (including cottonwood and willow) germinate on moist soils along the edge of a creek in spring. As the stream surface recedes during the first summer, the seedlings survive if the roots grow at the same rate as the water-level decline. Over a period of years, roots grow deeper as the land surface accretes from sediment deposition and/or the creek channel meanders away from the young tree or shrub.
Available water level data from wells were reviewed to identify parts of the Basin where the water table elevation might possibly be high enough to be reached by phreatophyte roots.
For screening purposes, a depth to water of less than 30 feet in wells was selected as a threshold for identifying possible phreatophyte areas. This depth allows for 10 to 15 feet of root depth, 5 feet of elevation difference between the water level in the well and the overlying true water table, and 15 feet of elevation difference between well heads and the bottoms of nearby creek channels.
A second limitation of available groundwater elevation data is the sparse geographic distribution of wells with measurements. Fortunately, many wells in the Basin with waterlevel data are located along Temescal Wash. Figure 4-16 shows a map of the eleven wells with relatively long-term water-level records. They are clustered into five areas. The only location where the typical spring depth to water was less than 30 feet was at the north end of the Basin, near the Flagler and Corona Non-Potable wells. Hydrographs of water levels in those wells are shown in Figure 4-17. Typical spring depths to water in the five wells in that area ranged from 15 to 27 feet. Slightly farther upstream—at the TVWD wells—typical depths to water were slightly greater than 30 feet. Depth to water increases rapidly to the west of Temescal Wash. At the Corona and Station 71 wells, the typical depth to water was 80 to 200 feet.
In summary, groundwater levels in the Basin appear to be too low to normally maintain a hydraulic connection with the Temescal Wash channel. Therefore, groundwater pumping does not deplete flow in Temescal Wash. Groundwater levels might be high enough to support phreatophytic riparian vegetation with roots extending 10-15 feet below the elevation of the creek bed.
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4.9.3. Riparian Vegetation
Vegetation data provide mixed evidence that the water table near some reaches of Temescal Wash is shallow enough to supply water to phreatophytes. Where tree and shrub roots are able to reach the water table, riparian vegetation is typically denser and greener than along reaches where vegetation is supplied only by residual soil moisture from the preceding wet season. Patches of dense riparian vegetation visible in multiple Google Earth (2021) aerial photographs from 1994-2014 are indicated by a crosshatch pattern in Figure 4-16. However, older and more recent aerial photographs indicate that the vegetation has not been a permanent feature of the landscape. The figure also shows the distribution of vegetation classified as Natural Communities Commonly Associated with Groundwater (NCCAG) by The Nature Conservancy in cooperation with DWR. Based on multiple historical vegetation surveys from the early 2000s, the Nature Conservancy prepared detailed statewide mapping of NCCAG vegetation that is accessible on-line (DWR et al. 2020). The extent of NCCAG vegetation is much greater than the extent of dense riparian vegetation and includes vegetation where the water table is certainly deeper than the root zone (such as near the Corona wells). Thus, some of the vegetation in the NCCAG polygons is probably not relying on groundwater. Furthermore, some of the plant species included in the NCCAG mapping are facultative phreatophytes, which means they will exploit a water table if it is within a reachable depth but otherwise survive on soil moisture (typically with smaller stature and greater spacing between plants). These species include red willow (Salix laevigata), which is the most common species mapped along Temescal Wash.
An additional test for groundwater dependence of riparian vegetation was to compare changes in groundwater elevation with changes in vegetation health during the 2012 to 2015 drought. Vegetation health can be detected by changes in the way the plant canopy absorbs and reflects light. The spectral characteristics of satellite imagery can be processed to obtain two metrics commonly used to characterize vegetation health: the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Moisture Index (NDMI). Both are calculated asratios ofselected visible and infrared light wavelengths. The Nature Conservancy developed a second on-line mapping tool called GDE Pulse that provides annual dry-season averages of NDVI and NDMI for each mapped NCCAG polygon for 1985-2018 to assist with the identification of groundwater dependent ecosystems (GDEs) (TNC 2020). In Figure 4-16, the polygons are color-coded by the change in NDMI from 2012 to 2015, with positive values in increasingly dark shades of green and negative values in increasingly dark shades of red.
Negative values indicate stress due to desiccation. The NDVI patterns were similar to the NDMI patterns.
Inconsistencies are immediately apparent. One would expect all of the polygons to have experienced moisture stress during the drought, but about one-third of them experienced little stress. In some cases, an unstressed polygon adjoins a highly stressed polygon, which would be unlikely if declining groundwaterlevels were the cause of the stress. In spite ofthese inconsistencies, the dominant pattern was a decrease in NDMI. This was notably the case for the red willow patch that occupies roughly the northern third of the Temescal Wash reach in the Basin.
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Further evidence of drought stress can be seen directly in aerial photographs. Figure 4-18 shows Google Earth (2021) photos of a reach adjacent to the golf course located about 1,000 feet upstream of the Corona Non-Potable wells. Photographs of the same location in 2012, 2014 and 2016 are shown. There was little apparent change from 2012 to 2014, but by 2016 many of the trees along the central channel appeared to be dead.
Water levelsin wells with relatively shallow depth to water declined 15 to 25 feet during 2012 to 2015, albeit unevenly in some wells. Thus, the declining NDMI values and substantial vegetation mortality both occurred during the same period that groundwater levels declined.
Notably, most of the water-level decline was between 2014 and 2016, which was the period when most of the vegetation mortality occurred. The correlation between groundwaterlevels and vegetation health does not necessarily prove causality, because other sources of water also became more scarce, including rainfall, irrigation return flow and wastewater discharges to Temescal Wash upstream of the site in the photograph. Rainfall at Elsinore during water years 2013 through 2016 averaged 5.96 inches, or 56 percent of the long-term average. The greater abundance of brown areas on the golf course fairways in 2016 relative to 2014 and 2012 suggest that irrigation had been curtailed due to the drought. The TVWD wastewater treatment plant located two miles upstream of the photo site, at the upstream end of the patch of dense riparian vegetation, normally discharges about 15 acre-feet per month (equivalent to 0.25 cfs) of treated wastewater to Temescal Wash, as shown in Figure 4-19.
Those discharges were discontinued from November 2012 through at least November 2018 except for one three-month period in winter 2015. The normal discharge could supply roughly one-third of the summer evapotranspiration (ET) demand of the entire reach of vegetation between the discharge point and the end of the Basin.
Older historical aerial photographs show that dense riparian vegetation was not always present prior to the 1990s (that is, prior to the Google Earth imagery). Figure 4-20 shows aerial photographs taken in 1967 of a 2-mile reach of Temescal Wash in the northern part of the Bedford-Coldwater Basin. It includes the area shown in Figure 4-18 (green rectangle).
There was almost no dense riparian vegetation anywhere along the Wash in 1967. Two factors probably contributed to the lack of vegetation. First, precipitation had been consistently below average since 1947 (see additional discussion in Chapter 5). Second, groundwater pumping was higher in those days to support irrigation of citrus groves (some of which are visible in the photograph). Pumping from the Bedford area averaged 3,000 acre-feet per year (AFY) during 1947 to 1967 (WEI 2015b) versus 1,800 AFY during 2015 to 2019. Both of these factors probably contributed to low surface flow and low groundwater levels, which together killed any prior dense riparian vegetation or prevented such vegetation from becoming established.
In summary, the extent, density and health of riparian vegetation has been variable historically. Vegetation appears to become denser and lusher when surface flow is more abundant and groundwater levels are consistently shallow, and it dies back during droughts and when groundwater levels are low. At any given time, the extent to which riparian vegetation along some reaches of Temescal Wash is phreatophytic and therefore affected by groundwater levels is unclear. The presence of groundwater elevations that are probably Bedford-Coldwater GSP 4-15
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within reach of phreatophyte roots, the presence of patches of dense riparian tree canopy, and the co-occurrence of groundwater declines and vegetation stress and mortality within the past decade all suggest that some vegetation is dependent on groundwater. However, other drought-related decreases in water availability could have contributed to the observed impacts on vegetation. Additional information regarding the true water table depth in the riparian zone and a more comprehensive evaluation of rainfall, irrigation, and wastewater discharge time series is needed to confirm the degree of vegetation dependence on groundwater levels.
4.9.4. Wetlands
The NCCAG vegetation mapping tool also includes a wetlands map, which is reproduced here with simplified mapping categories in Figure 4-21. In the Bedford-Coldwater Basin, almost all of the wetland polygons are within the Temescal Wash channel and accounted for in the preceding discussion of riparian vegetation. The wetland categories for those polygons are mostly marsh (palustrine) or riverine and characterized as seasonally flooded. Vegetation along the low-flow channel is classified as permanently or semi-permanently flooded, which a brief inspection of aerial photographs shows is clearly incorrect. A handful of small wetland polygons were mapped in upland areas west of Temescal Wash. Most are high up in the stream canyons where perennial stream flow or shallow groundwater is sustained by small amounts of groundwater inflow from the bedrock tributary areas and not affected by pumping in the main part of the Basin. Several patchestotaling 1.4 acres are midway between the wash and western Basin boundary, where regional groundwater levels are many tens of feet below the ground surface. The seasonal flooding orsaturation thatsupportsthe wetlandtype vegetation almost certainly derives from pooled rainfall runoff or interflow rather than discharge of regional groundwater.
The Western Riverside County Multiple Species Habitat Conservation Plan (MSHCP) was reviewed for additional information regarding plant species that might be affected by groundwater (Western Riverside County Regional Conservation Authority 2020). Two large regions mapped as narrow endemic plants and criteria area species partially overlap the Basin.
However, those categories together contain 16 upland plant species that are unaffected by groundwater.
Therefore, the few small areas mapped as wetlands outside the Temescal Wash channel would not be affected by pumping and groundwater levels.
4.9.4.1. Animals Dependent on Groundwater
Animals that depend on groundwater include fish and other aquatic organisms that rely on groundwater-supported stream flow and amphibious or terrestrial animals that lay their eggs in water. Management of habitat for animals typically focuses on species that are listed as threatened or endangered under the state or federal Endangered Species Acts. That convention is followed here. Flow in Temescal Wash is too ephemeral to support migration of anadromous fish (such as steelhead trout), and the watershed upstream of the Basin does not have stream reaches with perennial cool water suitable for spawning and rearing.
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The MSHCP includes mapped areas that are potential habitat for several animal species. The western edge of a very large habitat area for burrowing owl overlaps the eastern edge of the Basin. However, the owl is an upland species that is not dependent on riparian or wetland vegetation.
The coastal California gnatcatcher is a bird species federally listed as threatened. Critical habitat areas delineated by the U.S. Fish and Wildlife Service that are in or near the Basin are shown in Figure 4-22. The habitat polygons are all in upland areas, but a few of them overlap tributary streams underlain by narrow, shallow alluvial bodies that extend outward from the main Basin area. Groundwater in those tributary creek valleys is sustained by gradual discharge from fractured bedrock in the watershed areas, and there is little or no local groundwater pumping. To the extent that vegetation along the tributary stream valleys provides gnatcatcher habitat, it would be unaffected by pumping in the main Basin area.
In summary, there do not appear to be any listed animal species that would potentially be impacted by groundwater pumping or water levels. More common species that use riparian shrubs and trees along Temescal Wash could potentially be impacted during droughts if lowered groundwater levels cause vegetation die-back or mortality.
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Path: T:\Projects\Bedford Coldwater GSP 80802\GRAPHICS\Figure 4-6 Corona Well 3 Hydrograph.gpj Figure 4-6
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Path: T:\Projects\Bedford Coldwater GSP 80802\GIS\Maps\Figures\GSP Figures\Chapter 4 - GW Conditions\Figure 4-7 Groundwater Elevation Contours April 2015.mxd !(
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Figure 4-7
Groundwater
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Path: T:\Projects\Bedford Coldwater GSP 80802\GIS\Maps\Figures\GSP Figures\Chapter 4 - GW Conditions\Figure 4-8 Groundwater Elevation Contours April 2018.mxd !(
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Figure 4-8
Groundwater
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Figure 4-9
Concepts of
Land Subsidence
Source: Galloway et al., 1999.
After LSCE et al., 2014.
Area of
Largest Subsidence
Land
Subsidence
Regional clay layer Discontinuous
clay interbeds
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Path: T:\Projects\Bedford Coldwater GSP 80802\GIS\Maps\Figures\GSP Figures\Chapter 4 - GW Conditions\Figure 4-10 Basin-Wide Subsidence Estimates from Satellite Measurements.mxd !"a$
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Bedford-Coldwater Basin
Subsidence Estimates from Satellite Measurements
High : 0.05 feet
Low : -0.05 feet
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Data Source:
Subsidence estimates from satellite measurements provided by the TRE ALTAMIRA InSAR provided by the California Department of Water Resources.
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Basin-Wide Subsidence
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Path: T:\Projects\Bedford Coldwater GSP 80802\GIS\Maps\Figures\GSP Figures\Chapter 4 - GW Conditions\Figure 4-11 Wells with Water Quality Data.mxd !(
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!( Well with Water Quality Data from State Water
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!( Well with Water Quality Data from California
Department of Water Resources
!( Well with Water Quality Data from Regional Water
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!( Well with Water Quality Data from United States
Geological Survey
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Figure 4-11
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4-27
Path: T:\Projects\Bedford Coldwater GSP 80802\GIS\Maps\Figures\GSP Figures\Chapter 4 - GW Conditions\Figure 4-12 TDS Concentrations.mxd !(
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Figure 4-12
Total Dissolved Solids
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Path: T:\Projects\Bedford Coldwater GSP 80802\GIS\Maps\Figures\GSP Figures\Chapter 4 - GW Conditions\Figure 4-13 NO3 Concentrations.mxd !(
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Figure 4-13
Nitrate as Nitrogen
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4-29
Path: T:\Projects\Bedford Coldwater GSP 80802\GIS\Maps\Figures\GSP Figures\Chapter 4 - GW Conditions\Figure 4-14 Watersheds and Gauging Stations.mxd !
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?Æ
City of Corona
WRF-3
Wastewater
Discharge
USGS Station No:
11072100
USGS Station Name:
Temescal Creek About Main Street, Corona CA
USGS Station No:
11071760
USGS Station Name:
Coldwater Canyon Creek near Corona CA
USGS Station No:
11071900
USGS Station Name:
Temescal Creek at Corona Lake near Corona CA
TVWD
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Path: T:\Projects\Bedford Coldwater GSP 80802\GRAPHICS\Figure 4-15 Local Streamflow 2013 through 2020.gpj Figure 4-15
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4-31
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Dense riparian trees
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Path: T:\Projects\Bedford Coldwater GSP 80802\GRAPHICS\Figure 4-17 Hydrographs for Wells with Shallow Depth to Groundwater.gpj Figure 4-17
Hydrographs for Wells with
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June 2012
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Figure 4-18
Recent Riparian
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Imagery
4-34
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Path: T:\Projects\Bedford Coldwater GSP 80802\GRAPHICS\Figure 4-19 TVWD WW Discharge.gpj Figure 4-19
TVWD Wastewater
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4-35
Path: T:\Projects\Bedford Coldwater GSP 80802\GIS\Maps\Figures\GSP Figures\Chapter 4 - GW Conditions\Figure 4-20 1967 Aerial Photo.mxd Approximate Extent
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Path: T:\Projects\Bedford Coldwater GSP 80802\GIS\Maps\Figures\GSP Figures\Chapter 4 - GW Conditions\Figure 4-21 Wetlands in Basin.mxd !"a$
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NCCAG Wetlands in Basin
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Path: T:\Projects\Bedford Coldwater GSP 80802\GIS\Maps\Figures\GSP Figures\Chapter 4 - GW Conditions\Figure 4-22 Gnatcatcher Habitat.mxd !"a$
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Figure 4-22
Coastal California
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4-38
Bedford-Coldwater GSP 5-1
TODD GROUNDWATER,
H&H Water Resources,
and Stantec
5. WATER BUDGET
A water balance (or water budget) is a quantitative tabulation of all inflows, outflows, and storage change of a hydrologic system. The Sustainable Groundwater Management Act (SGMA) requires that water balances be prepared for the groundwater system and surface water system of a basin. If a basin contains multiple management areas, separate balances must be developed for each of them. Furthermore, water budgets must be developed fortime periods representing historical, current, future no project (baseline), and future growth plus climate change (growth plus climate change) conditions.
This chapter presents the basis for selecting the water budget analysis periods, describes the boundaries and general characteristics of three management areas within the BedfordColdwater Subbasin (Basin), describes modeling tools used to estimate some water budget items, and presents the surface water and groundwater budgets.
5.1. WATER BUDGET METHODOLOGY
Annual balances were developed for water years 1990 through 2018, the period simulated by the numerical groundwater model. This interval was selected because it is a long hydrologic period for which important water budget data were available. The model is described in Appendix G and provides estimates for several components of the water balance for which direct measurements are not available: flows between groundwater and surface water bodies, flows to and from adjacent basins, evapotranspiration of riparian vegetation, and storage change. The numerical model allows a dynamic and comprehensive quantification of the water balance wherein all estimated water balance elements are reconciled and are calibrated to groundwater level changes over time. Accordingly, the numerical model is the best tool to quantify those water balance components. It will be updated regularly through the Groundwater Sustainability Plan (GSP) implementation process, providing a better understanding of the surface water-groundwater system and a tool to evaluate future conditions and management actions.
5.2. DRY AND WET PERIODS
Dry and wet periods in historical hydrology can be identified on the basis of individual years or sequences of dry and wet years. GSP Regulations require that each year during the water budget analysis period be assigned a water year type, which is a classification based on the amount of annual precipitation. Figure 5-1 shows annual precipitation at Elsinore (National Oceanic and Atmospheric Administration (NOAA) Station GHCND:USC00042805) for water years 1899 through 2020. Water year types are also indicated and are assigned to five categories corresponding to quintiles of annual precipitation. The categories used here (dry, below normal, normal, above normal and wet) accurately describe the quintiles. These categories differ from the nomenclature commonly used in the Central Valley (critical, dry, below normal, above normal and wet) and elsewhere but do not accurately describe local categories and are based on the Sacramento River Index, which has little relevance to Bedford-Coldwater GSP 5-2
TODD GROUNDWATER,
H&H Water Resources,
and Stantec
conditionsin the Basin. The quintile divisionsfor precipitation during 1899 to 2020 at the Lake Elsinore station are shown in Table 5-1.
Table 5-1. Water Year Type Classification (Lake Elsinore station) Water Year Type Range as Percent of Mean
Precipitation Range
(inches)
Wet W >139 > 16.5
Above Normal AN 101 to 139 12.0 to 16.5
Normal N 75 to 101 8.9 to 12.0
Below Normal BN 56 to 75 6.6 to 8.9
Dry D <56 < 6.6
Average precipitation for 1899 to 2020 was 11.88 inches per year Individual wet and dry years are not particularly useful for groundwater management in basins where groundwater storage greatly exceeds annual pumping and recharge, which is the case in the Basin. In those basins, multi-year droughts and sequences of wet years are more relevant, because they relate to the amount of operable groundwater storage needed to support sustainable groundwater management. Multi-year wet and dry periods can be identified from a plot of cumulative departure of annual precipitation, which is also shown on Figure 5-1. Wet periods appear as upward-trending segments of the cumulative departure curve, and droughts appear as declining segments. By far the largest climatic deviationsin this record were the sustained wet conditions from 1937 to 1944 and dry conditions from 1946 to 1965. These events pre-dated the most recent 30 years, which is the period that the California Department of Water Resources (DWR) states should be used for determining year types (DWR 2016c). They also pre-date the period simulated by the groundwater model.
However, large wet and dry events like those could recur in the future, and it is prudent to consider climate uncertainty in planning for groundwater sustainability.
5.3. WATER BALANCE ANALYSIS PERIODS
GSP regulations require evaluation of the water balances over historical, current, and future periods. The historical period must include at least 10 years, and the future period must include exactly 50 years. The duration of the current period is not specified, but to be consistent with SGMA concepts it needs to include several years around 2015, which was the implementation date of SGMA. Historical and current analysis periods for the Basin were selected from within the 1990 through 2018 modeling period. Ideally, each period is characterized by average precipitation and relatively constant land and water use.
Urbanization in the Basin has been gradual throughout the 1990 to 2018 period. The historical period is represented by water years 1993 through 2007, and the current period by water Bedford-Coldwater GSP 5-3
TODD GROUNDWATER,
H&H Water Resources,
and Stantec
years 2010 to 2013. Those periods had 101 percent and 102 percent of the 1899 to 2020 average annual rainfall, respectively.
The future period is intended to represent conditions expected to occur over the next 50 years. The modelsimulation period is only 29 years(1990 to 2018). To obtain a 50-year period, simulations of future conditions used the 1993 through 2017 sequence of rainfall and natural stream flow repeated twice. Average annual precipitation during 1993 to 2017 was 94 percent of the long-term average. For the baseline scenario, no adjustments were made to the hydrologic sequence. Adjustments made to simulate future climate change are described in following sections.
5.4. MANAGEMENT AREAS
As defined in the GSP regulations, a Management Area (MA) is an area within a basin for which the GSP may identify different minimum thresholds, measurable objectives, monitoring, or projects and management actions based on differences in water use sector, water source type, geology, aquifer characteristics, or other factors. The Basin has been divided into two MAs. They are described below and in more detail in Appendix I, and their boundaries are shown in Figure 5-2.
5.4.1. Bedford Management Area
The Bedford MA occupiesroughly the eastern two-thirds of the Basin. It isseparated from the Coldwater MA by the Glen Ivy Fault, which is a partial barrier to groundwater flow. The Bedford MA connects to the Elsinore Subbasin in the south and the Temescal Basin at the north end of the Basin. Some subsurface inflow from the Elsinore Subbasin to the south, and subsurface outflow to the Temescal Basin is also possible. Temescal Wash flows along the length of the Bedford MA. It also exits the north end of the Basin but traverses a bedrock reach before entering the Temescal Basin.
5.4.2. Coldwater Management Area
The Coldwater MA is the part of the Basin west of the Glen Ivy Fault. Because of downward movement on that side of the fault, Basin thickness is much greater than in the Bedford MA.
A large open-pit aggregate mine is located in the southern part of this MA. Several streams enter the Coldwater MA from watersheds on the eastern slopes of the Santa Ana Mountains.
5.5. METHODS OF ANALYSIS
Complete, itemized surface water and groundwater balances were estimated by combining raw data (rainfall, stream flow, municipal pumping, and wastewater percolation from septic tanks and wastewater treatment plant discharge) with values simulated using models3 .
3 Water balance values are shown to nearest acre-foot to retain small items, but entries are probably accurate to only two significant digits.
Bedford-Coldwater GSP 5-4
TODD GROUNDWATER,
H&H Water Resources,
and Stantec
Collectively, the models simulate the entire hydrologic system, but each model or model module focuses on part of the system, as described below. In general, the models were used to estimate flows in the surface water and groundwater balancesthat are difficult to measure directly or that relate to time-dependent groundwater levels. These include surface and subsurface inflows from tributary areas, percolation from stream reaches within the Basin, groundwater discharge to streams, potential subsurface flow from the neighboring subbasin and between MAs, the locations and discharges of pumping wells, consumptive use of groundwater by riparian vegetation, and changes in groundwaterstorage. Descriptions of the inflows and outflows to the surface water and groundwater models are included below in Sections 5.6 and 5.7.
5.5.1. Rainfall-Runoff-Recharge Model
This Fortran-based model developed over a number of years by Todd Groundwater staff simulates hydrologic processes that occur over the entire land surface, including precipitation, interception4
, infiltration, runoff, evapotranspiration, irrigation, effects of impervious surfaces, pipe leaks in urban areas, deep percolation below the root zone, and shallow groundwater flow to streams and deep recharge. The model simulates these processes on a daily time step for 242 “recharge zones” delineated to reflect differences in physical characteristics as well as basin and jurisdictional boundaries. Simulation of watershed areas outside the Basin is included to provide estimates of stream flow and subsurface flow entering the Basin. Daily simulation results were subtotaled to monthly valuesfor input to the groundwater model. Additional details regarding the rainfall-runoff-recharge model can be found in Appendix G and the model code is available on request.
5.5.2. Groundwater Model
The groundwater flow model uses the MODFLOW 2005 code developed by the United States Geological Survey (USGS) that is a public domain open-source software as required by GSP regulation §352.4(f)(3). The model produces linked simulation of surface water and groundwater, as described below. Additional documentation of the model and calibration is provided in Appendix G.
5.5.2.1. Surface Water Module
Stream flow in MODFLOW is simulated using the Streamflow Routing Package (SFR) where a network of stream segments represents the small streams entering the Basin from Temescal Wash and tributary watersheds.
Surface water inflows to Temescal Wash were obtained from a similar groundwater flow model of the Elsinore Subbasin. Smallstream inflows were estimated using the rainfall-runoffrecharge model. Each stream segment is divided into reaches, one per model grid cell traversed by the segment. Flow isrouted down each segment from reach to reach. Along each 4 Interception refers to precipitation that does not reach the soil, but instead falls on (and is intercepted by) plant leaves, branches, and plant litter, and is subject to evaporation loss.
Bedford-Coldwater GSP 5-5
TODD GROUNDWATER,
H&H Water Resources,
and Stantec
reach mass balance is conserved in the stream, including inflow from the upstream reach and tributaries, inflow from local runoff, head-dependent flow across the stream bed to or from groundwater, evapotranspiration losses and outflow to the next downstream reach. Flow across the stream bed is a function of the wetted channel length and width, the bed permeability and the difference in elevation between the stream surface and groundwater at the reach cell. Wetted width and depth of the stream are functions of stream flow.
5.5.2.2. Groundwater Module
The MODFLOW groundwater model is constructed to cover the entire Basin. The model grid size is oriented at 40 degrees west of north (N40W) so that it is oriented consistent with the key hydrologic features including streams and faults. The model grid size uses a uniform 100 feet (ft) horizontal grid spacing to provide sufficient resolution to resolve hydraulic gradients, well drawdown cones, and groundwater-surface water interactions in the Basin.
The Basin extends up a number of narrow tributary stream canyons. These narrow canyons can be problematic to simulate using MODFLOW because they can cause difficult numerical stability issues. To limit these effects, the model grid extends up these canyons until the canyon islessthan 3 grid cells wide, orto the extent where the alluvialsediments are regularly saturated. Areas upstream of these locations have been simulated using boundary conditions to estimate inflows based on groundwater conditions and surface water model results.
The numerical model has been constructed to reflect the hydrogeological conceptual model developed for the GSP. The vertical extent of the Basin is based on the mapped depth to consolidated rock. The elevation of surface features and streambed elevations have been derived from geographic information system (GIS) files developed from the local topography and stream information.
Citrus orchards irrigated with groundwater were common in the Basin in the early 1990s, but except for one small grove in the Coldwater MA those have all been replaced by urban development. The citrus orchards present in the early 1990s were almost all replaced by urban development by 2018. Agricultural irrigation pumping of these orchards was estimated by the rainfall-runoff-recharge model, with pumping assigned to a hypothetical irrigation well at the center of each irrigated recharge zone. This pumping was phased out overtime as urban development occurred. Urban irrigation is supplied by the municipal water system, which uses imported water and local wells. Municipal well extractions are known and are entered directly into the model. All major pumpers in the Basin report their annual production to WMWD, which was the source of data for several non-municipal pumping wells. Pumping at private domestic wells is not reported and is not included in the model. The number of those wells is thought to be small, and their total production is almost certainly negligible in the context of the overall Basin water budget.
Bedford-Coldwater GSP 5-6
TODD GROUNDWATER,
H&H Water Resources,
and Stantec
5.5.3. Simulation of Future Conditions
GSP regulations §354.18(c)(3) require simulation of three future scenarios to determine their effects on water balances, yield, and sustainability indicators. For this scenario, the growth and climate change scenarios were combined, resulting in the following two scenarios:
Baseline. This represents a continuation of existing land and water use patterns, imported water availability, and climate.
Growth Plus Climate Change. This scenario implements anticipated changes in land use and associated water use, such as urban expansion, and anticipated effects of future climate change on local hydrology (rainfall recharge and stream percolation) and on the availability of imported water supplies.
Both the future simulations assume a constant level of development and related water demand in the Basin. Development in the growth plus climate change simulation is not phased in over time. This is the best way to demonstrate whether 2068 land use is sustainable because it allows for assessment of the effects of variations in climactic conditions (wet and dry cycles) on groundwater conditions, avoids subjective decisions about the concurrent timing of droughts and development, and providestime for the full effect of future conditions on groundwater to become apparent.
5.5.3.1. Baseline Scenario
The baseline simulation is a 50-year period, as required by SGMA regulations, with water budget components developed using the criteria and assumptions described below. Initial water levels are simulated water levels for September 2018 from the historical calibration simulation. That year represents relatively recent, non-drought conditions. These simulated water levels are internally consistent throughout the model flow domain and reasonably matched measured water levels at wells with available data (see Appendix G for discussion of model calibration).
Surface water and other inflows came from multiple sources. Monthly inflows in Temescal Wash were obtained from the baseline and growth plus climate change simulations produced by the Elsinore Subbasin groundwater model (Carollo and Todd 2021), which is concurrently being used to develop the GSP for that Subbasin. Small stream and bedrock inflows simulated for 1993 to 2017 of the calibration model period were repeated twice to obtain 50 years of data.
In the baseline scenario, land use remains the same as the current conditions. In the model, land use is represented by 2014 land use mapped by remote sensing methods and obtained from DWR, adjusted for subsequent urbanization identified in Google Earth imagery.
Municipal, commercial, and industrial (M&I) and private pumping were assumed to remain at existing levels. Initial estimates were obtained by calculating average pumping for each calendar month during 2010 through 2018 and applying those averages in every year of the Bedford-Coldwater GSP 5-7
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future simulation. This approach omits additions to and withdrawals from Coldwater MA storage accounts by the three municipal agencies with wells in that MA. Municipal use of imported water was also assumed to remain at existing levels. From the standpoint of the groundwater budget, total municipal water use was used only to estimate pipe leaks. Use of imported water by the Temescal Valley Water District (TVWD) was obtained from that agency’s 2015 Urban Water Management Plan (RMC and Woodard & Curran 2017), and imported water use in the parts of the City of Corona (Corona) and Elsinore Valley Municipal Water District (EVMWD) service areas within the Basin were assumed to be the same on a per-acre basis for developed areas.
The Baseline scenario also assumes wastewater percolation and recycling continue as they have in recent years. Discharges from the TVWD Water Reclamation Facility (WRF) to Temescal Wash were discontinued in 2013. All of the plant outflow is recycled for irrigation during spring, summer, and fall (assumed April through November), and most or all of it is percolated in ponds at the WRF when irrigation demand is low (December through March).
5.5.3.2. Growth Plus Climate Change Scenario
The growth plus climate change scenario incorporated anticipated effects of climate change, urban development, and associated changes in water and wastewater management. In this scenario, rainfall and reference evapotranspiration (ET0) were adjusted to 2070 conditions using monthly multipliers developed by DWR based on climate modeling studies. The multipliers were applied to historical monthly data for the 1993 to 2017 hydrologic period used in the model. DWR prepared a unique set of multipliers for each foursquare kilometer (km2
) cell of a grid covering the entire state. Nine climate grid cells overlie the Basin and its tributary watershed areas. For each recharge analysis polygon in the rainfall-runoff-recharge model, multipliers from the nearest climate grid cell were used. The climate in 2070 is expected to be drier and warmer than at present.
Figure 5-3 compares average monthly precipitation and ET0 before and after applying the climate change multipliers. Simulations of irrigated turf in the rainfall-runoff-recharge model indicated that the combined effect of the warmer and drier climate will be to increase annual irrigation demand by about 10 percent.
In the growth plus climate change scenario, bedrock inflow and surface inflow from tributary streams along the perimeter of the Basin were re-simulated using the rainfall-runoff-recharge model to reflect the effects of urban development in some of the tributary watersheds and of climate change. Urbanization also increased surface runoff within the Basin, which was routed to small streams and Temescal Wash.
Projected land use in 2068, shown in Figure 5-4, was developed on the basis of population projections, land use designations in the Temescal Canyon Area Plan (Riverside County 2018), assumed urban infill, and topography. A comparison of land use acreage by land use category and management area for 1990, 2018, and 2068 is shown in Table 5-2. Conversion of grassland to residential land use was the dominant change in both management areas and also occurred in tributary watershed areas.
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Total municipal water use in 2068 was estimated to be double the amount in 2018. This estimate is an approximate average of several factors. The Temescal Canyon Area Plan (Riverside County 2018) assigns developed land uses to almost the entire Basin area, and the area of undeveloped lands is presently about equal to the area of developed lands. Thus, the amount of developed land could plausibly double. However, the Area Plan also included estimates of future population that would extrapolate to a 2068 population only 58 percent greater than the current population. Finally, TVWD’s 2015 Urban Water Management Plan (RMC and Woodard & Curran 2017) included projections of future water use out to 2040.
Extrapolating those trends to 2068 indicates water use 1.55 times greater than in 2015.
For the growth plus climate change scenario, average annual groundwater pumping in the Coldwater MA was assumed to equal average historical pumping during 2010 through 2017, with an increase proportional to the estimated amount of irrigation return flow from future increased use of imported water. In the Bedford MA, average annual groundwater pumping was assumed to be equal to 2020 production volumes. Municipal pumping in Coldwater was distributed among wells in proportion to their averages during 2010 to 2017 and in Bedford it was distributed as recorded in 2020. All remaining municipal water use was assumed to be obtained from imported water.
Water pipe leak rates in the EVMWD and City of Corona service areas were assumed to decrease to 5 percent of delivered water from the rates reported in the 2015 Urban Water Management Plans (7.0 percent and 6.6 percent, respectively). The leak rate in the TVWD service area was assumed to continue at the low rate reported in 2015 (2 percent).
Wastewater generation was assumed to double by 2068, in proportion to the increase in total urban water use. Wastewater disposal was assumed to change, however. In recent years more of the outflow from the TVWD WRF has been percolated in ponds than has been recycled for irrigation. This proportion was assumed to reverse, such that all outflow would be recycled for irrigation during April through November and all would be percolated in ponds during November through March. The small discharge from Corona WRF-3 to Temescal Wash at the northern end of the Basin was assumed to be eliminated, consistent with the City of Corona’s plans to decommission that WRF.
In the growth plus climate change scenario, mining operations were assumed to have ended and the mine areasto have been converted to stormwater control facilities with groundwater recharge capacity during high runoff periods.
Table 5-2. Bedford-Coldwater Basin Land Use in 1990, 2018 and 2068 (acres) Bedford MA Coldwater MA Tributary Watersheds
1990 2018 2068 1990 2018 2068 1990 2018 2068
Citrus 1,261 0 0 719 32 32 0 0 0
Grassland 2,403 1,603 413 187 103 33 16,703 16,429 16,174 Shrubs/Trees 368 144 64 173 138 82 13,777 13,693 13,693 Dense riparian 256 159 159 8 27 27 0 0 0
Sparse riparian 303 303 303 0 0 0 0 0 0
Open water 0 0 0 0 0 0 0 0 0
Low-density residential 199 529 485 66 88 88 0 0 0
Residential 179 1,379 2,725 76 405 606 0 94 327
Turf 7 263 326 0 170 226 0 85 107
Commercial 0 30 671 24 33 50 0 0 0
Industrial 232 469 469 0 0 0 0 0 0
Quarry 434 252 252 441 588 588 365 555 555
Vacant 785 1,232 561 38 148 0 0 0 0
Land Use
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5.6. SURFACE WATER BALANCE
This section describes and quantifies the water balance of creeks and rivers that cross the Basin. All significant inflows to and outflows from these surface water bodies are included in the water balance. The surface water balance shares two flows in common with the groundwater balance: 1) percolation from surface water to groundwater and 2) seepage of groundwater into surface water. Each of these is an outflow from one system and an inflow to the other.
Annual surface water balances during 1990 to 2018 were compiled from monthly data for each MA, and average annual water balances were calculated for each of the three analysis periods (1993 to 2007 and 2010 to 2013 for the historical simulation, and 2019 to 2068 for the future simulations). Key features of the surface water balancesfor each management area and analysis period are described below, followed by additional information about the methods used to quantify items in the water balances.
Historical annual surface water balances for the Bedford MA during 1990 to 2018 are shown in Figure 5-5 (upper graph). Average annual surface water budgets for the model, historical, current, and future budget analysis periods are listed in Table 5-3 and detailed surface water budget tables are included in Appendix J. Inflow occurs predominantly in wet years and derives from Temescal Wash, east side tributaries and runoff, and streams entering from the Coldwater MA, in descending order of magnitude. Outflow is almost entirely surface outflow in Temescal Wash to Temescal Basin.
In the baseline simulation, discharges of reclaimed water to Temescal Wash consisted only of the small flowsfrom Corona WRF-3; TVWD WRF discharges had already ceased in 2013. Other inflows to the Bedford MA were close to the magnitudes of those flows during the historical and current periods. In the growth plus climate change scenario, Temescal Wash inflows from the Elsinore Subbasin were slightly larger due urbanization and wastewater discharges in that area. Local tributary inflows were slightly reduced due to the warmer, drier climate. There was little change in net stream percolation and outflow to the Temescal Basin.
Annual surface water balances for the Coldwater MA are also shown in Figure 5-5 (middle graph) and Table 5-3. The only inflow of significance is from tributary streams draining the eastern slopes of the Santa Ana Mountains. Those inflows decreased somewhat under the growth plus climate change scenario because of warmer, drier climatic conditions. Less inflow led to less stream percolation (33 percent lower than historical) and less outflow to the Bedford MA (14 percent lower than historical).
A substantial amount of water is imported into the Basin. It is delivered directly to users and does not flow into streams or lakes. Imports began in 1992, and annual amounts since then are shown in Figure 5-5 (bottom graph). Imported water consists of State Water Project (SWP) water purchased from the Metropolitan Water District of Southern California (Metropolitan) and delivered to TVWD through the Temescal Valley Pipeline.
Table 5‐3. Average Annual Surface Water Budgets
Bedford Management Area Coldwater Management Area
Historical
1993 to 2007
Current
2010 to 2013
Baseline1
2019 to 2068
Growth Plus
Climate Change1
2019 to 2068
Historical
1993 to 2007
Current
2010 to 2013
Baseline1
2019 to 2068
Growth Plus
Climate Change1
2019 to 2068
Inflows
Temescal Wash 13,560 10,761 10,892 12,857 0 0 0 0Tributary inflow 8,201 8,522 7,412 6,477 6,280 6,164 5,278 4,611 Wastewater discharges 712 1,227 60 0 0 0 0 0Groundwater flow into streams 791 1,137 990 1,380 16 2 2 1 Total Inflows 23,264 21,646 19,354 20,714 6,296 6,166 5,279 4,612 Outflows
Stream percolation ‐1,564 ‐2,015 ‐1,661 ‐1,714 4,160 3,216 2,780 2,779 Surface outflows ‐21,700 ‐19,631 ‐17,693 ‐19,000 2,136 2,950 2,499 1,834 Total Outflows ‐23,264 ‐21,646 ‐19,354 ‐20,714 6,296 6,166 5,279 4,612 1 The 50‐year future baseline simulation uses historical hydrology for 1993 to 2017 two times in succession.
Inflow or Outflow
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5.6.1. Inflows to Surface Water
5.6.1.1. Precipitation and Evaporation
Precipitation and evapotranspiration on the land surface are accounted for in the rainfallrunoff-recharge model. Those processes are not included in the surface water balances, which address only water in stream channels, lakes, and imported water. Precipitation and evaporation on the surface of creeks and rivers are invariably miniscule percentages of total stream flow and are not included in the water budget.
5.6.1.2. Tributary Inflows
Tributary inflows to the Basin are from Temescal Wash and tributary watersheds along the east and west sides of the Basin. Temescal Wash inflows were obtained from the Elsinore Subbasin groundwater model. Surface inflowsfrom nine Santa Ana Mountain watershedsthat discharge to the Coldwater MA were estimated using the rainfall-runoff-recharge model, with daily flows subtotaled to monthly flows for input to the groundwater model. Inflows from six eastside tributary watersheds that discharge to the Bedford MA were similarly simulated.
5.6.1.3. Valley Floor Runoff
The rainfall-runoff-recharge model simulates runoff from valley floor areas, which include impervious surfaces in urban areas. Runoff from valley floor areas was added to flows in tributary streams or Temescal Wash at several locations.
5.6.1.4. Wastewater Discharges
Reclaimed water was discharged from TVWD WRF to Temescal Wash beginning around 1991 and gradually increasing to about 2 cubic feet persecond (cfs) during 2008 to 2012. Discharges ceased after that as TVWD increased its capacity to percolate the water in winter and recycle it for irrigation in summer. The City of Corona’s WRF-3 discharges small amounts of reclaimed water to Temescal Wash near the downstream end of the Basin, averaging about 0.2 cfs but increasing to as much as 0.6 cfs in some winters. The City plans to decommission this plant and route its inflow to WRF-1 in the Temescal Basin in Corona.
5.6.1.5. Groundwater Discharge to Streams
Groundwater discharges into streams when the adjacent water table is higher than the stream bed or the water level in the stream. This occurs sometimes along Temescal Wash in the Bedford MA. Because groundwater levels fluctuate over time, estimates of these discharges were obtained from the groundwater model.
5.6.2. Outflows of Surface Water
5.6.2.1. Net Evaporation
Evaporation from streams is almost always a negligible fraction of total flow and is not explicitly itemized in the water budgets or simulated in the model.
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5.6.2.2. Surface Water Percolation to Groundwater
In wet years, percolation from streams along the reaches between the Basin boundary and Temescal Wash is a significant outflow of surface water. Along Temescal Wash in the Bedford MA, the Wash gains flow from groundwater in some reaches and loses it to groundwater in others, depending on the relationship between the stream surface and adjacent groundwater table. These exchanges vary in time as well as location, but over the long run they are of generally similar magnitudes. Because of this dynamic interaction between surface water and groundwater, estimates of flows across the bed of Temescal Wash were obtained from the groundwater model.
5.6.2.3. Surface Outflow from Management Areas and the Basin Surface outflow from the Coldwater MA to the Bedford MA was calculated by subtracting net percolation losses along the tributary streams from their inflows at the Basin boundary. The net losses were simulated by the groundwater model. Surface outflow in Temescal Wash to the Temescal Basin was calculated asthe residual in the surface water balance forthe Bedford MA.
5.7. GROUNDWATER BALANCE
Annual groundwater inflows and outflows for each management area for the 1990 to 2018 model simulation period are shown as stacked bars in Figure 5-6. Inflows are stacked in the positive (upward) direction and outflows are stacked in the negative (downward) direction. A similarstacked-bar chart for the baseline simulation isshown in Figure 5-7 and for the growth plus climate change simulation in Figure 5-8. Average annual groundwater budgets for each MA and budget analysis period are listed in Table 5-4 and detailed groundwater budget tables are included in Appendix J. Highlights of the water budgets are described below, followed by additional information on methods used to quantify each budget item.
In the Bedford MA, the major inflow is percolation from streams especially during wet years.
In recent years (2012 to 2018), reclaimed water percolation has become another major inflow. The major outflows include M&I pumping and groundwater discharge to streams.
Historically, agricultural pumping also has contributed to outflow from the basin but decreased to a negligible amount by 2007.
Percolation from streams—principally Temescal Wash—was similar across all analysis periods. This was because Temescal Wash inflows increased under the growth plus climate change scenario, offsetting decreased inflow from local tributary streams. Meanwhile, total pumping increased by 71 percent from the historical to the growth plus climate change scenario, which resulted in a slight increase in induced percolation from the Wash. The small increase in bedrock inflow under the growth plus climate change scenario was because urbanization of parts of the tributary watersheds produced enough additional recharge to more than offset the effects of climate change. Subsurface inflow progressively decreased and subsurface outflow increased from the historical period to the growth plus climate change scenario. This was caused by declining water levels in the Coldwater MA, which Bedford-Coldwater GSP 5-14
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reversed the direction of flow across the boundary between the MAs around the end of the historical period. Recharge from pipe leaksroughly doubled due to urbanization but remained a small fraction of total inflows (five percent) because of TVWD’s low reported pipe leak rate.
Overall in the Bedford MA, both future scenarios show increases in reclaimed water percolation.
Outflows in both scenarios also increased. The net result is a slightly decreased change in storage over the historical period, but the basin is still expected to have a positive change in storage (more inflow than outflow) under future conditions, even under growth and climate change projections.
In the Coldwater MA, percolation from streams occurs as infrequent, episodic events. As shown in Figure 5-6, percolation can range from 15,000 acre-feet (AF) in wet years to no stream percolation in dry years. M&I pumping has dominated basin outflows although it has decreased from its peak in the late 1990s. Similar to the Bedford MA, agricultural pumping was an outflow historically but decreased to negligible by 2001.
The differences between the historical, current, and future scenarios stem mostly from the years selected for inclusion in the averaging. Bedrock inflow decreased slightly in the growth plus climate change scenario because of the warmer, drier climatic conditions. The increase in dispersed recharge on both irrigated and non-irrigated lands under the growth plus climate change resulted from urbanization. A fraction of runoff from impervious surfaces is assumed to flow to adjacent pervious soils, creating localized concentrated recharge. This was included in the recharge for non-irrigated lands. As in the Coldwater MA, pipe leaks increased due to urbanization but remained only four percent of total inflows.
Overall in the Coldwater MA, in both future scenarios inflows significantly increase from dispersed rechange over non-irrigated land. Outflows are expected to decline as M&I pumping is projected to be limited in the future based on agreements between the GSA agencies. The combined increased inflow and decreased outflow results in significantly increased storage in future conditions, which reverses the historical water level declines in the Coldwater MA.
Table 5-4. Average Annual Groundwater Budgets
Bedford Management Area Coldwater Management Area
Historical
1993 to 2007
Current
2010 to 2013
Historical
1993 to 2017
Baseline1
2019 to 2068
Growth Plus
Climate
Change1
2019 to 2068
Historical
1993 to 2007
Current
2010 to 2013
Historical
1993 to 2017
Baseline1
2019 to 2068
Growth Plus
Climate
Change1
2019 to 2068
Groundwater Inflow
Subsurface inflow 480 103 353 102 93 10 90 41 34 48
Percolation from streams 1,564 2,015 1,516 1,661 1,714 4,160 3,216 3,327 2,780 2,779 Bedrock inflow 867 816 819 776 828 583 526 536 467 435
Dispersed recharge: non-irrigated land 776 1,040 740 929 1,031 327 487 330 1,164 1,575 Dispersed recharge: irrigated land 792 578 674 559 940 468 336 396 289 396 Pipe leaks 126 156 143 33 92 30 39 35 17 32
Reclaimed water percolation 391 587 638 1,868 2,161 0 0 0 0 0 Quarry recharge 85 21 92 162 471 0 0 0 0 0
Total Inflow 5,080 5,315 4,974 6,090 7,331 5,579 4,694 4,665 4,751 5,264 Groundwater Outflow
Subsurface outflow -179 -370 -205 -498 -423 -92 0 -55 -15 -7 Wells - M&I and domestic -1,235 -577 -1,110 -1,315 -1,895 -5,802 -2,969 -4,787 -3,002 -3,072 Wells - agricultural -728 -65 -460 0 0 -929 -186 -623 -40 -88 Groundwater discharge to streams -791 -1,137 -786 -990 -1,380 -16 -2 -10 -2 -1 Riparian evapotranspiration -482 -732 -512 -760 -1,015 -285 -234 -281 -154 -168 Quarry Operations / Losses -1,447 -1,845 -1,663 -2,422 -2,466 -606 -595 -653 0 0 Total Outflow -4,863 -4,726 -4,737 -5,986 -7,179 -7,730 -3,986 -6,410 -3,212 -3,337 Net Change in Storage
Inflows minus outflows 217 589 237 104 152 -2,152 708 -1,744 1,539 1,927 1 : The 50-year future simulation uses historical hydrology for 1993 to 2017 two times in succession.
Water Balance Items
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5.7.1. Inflows to Groundwater
Inflows to the groundwater flow system in both MAs are dominated by rainfall recharge and stream percolation, which vary widely from year to year depending on hydrologic conditions.
Variations in bedrock inflow from tributary watersheds is steadier because flow through fractured bedrock in those watersheds attenuatesthe recharge pulsesthat occurin wet years.
Urban sources ofrecharge including irrigation return flow and pipe leaks are less variable from year to year but gradually increased during the simulation period in parallel with urban growth.
5.7.1.1. Dispersed Recharge from Rainfall and Irrigation Dispersed recharge from rainfall and applied irrigation water is estimated by the rainfallrunoff-recharge model. The model simulates soil moisture storage in the root zone, with inflows from rainfall infiltration and irrigation, and outflows to evapotranspiration and deep percolation. Simulation is on a daily basis. In recharge zones with irrigated crops—which includes urban landscaping and agricultural irrigation (citrus)—irrigation is assumed to be applied when soil moisture falls below a certain threshold. When soil moisture exceeds the rootzone storage capacity,the excess becomes deep percolation. Rainfall and irrigation water comingle in the root zone and in deep percolation. For the purposes of displaying an itemized water balance, the amount of deep percolation derived from irrigation is estimated as a percentage of the simulated irrigation quantity, and the remainder of the dispersed recharge is attributed to rainfall. Deep percolation of applied irrigation water (irrigation return flow) is generally similar from year to year, whereas rainfall percolation varies significantly on an annual basis. Because urban landscape irrigation increased while agricultural irrigation decreased during the simulation period, total recharge on irrigated lands decreased only slightly. Water pipe leaks were estimated as the percentage of unaccounted for water listed in the 2015 Urban Water Management Plan (eight percent of delivered water, RMC and Woodard & Curran), distributed uniformly over areas of urban land use. Sewer pipes convey only water used indoors, and their leak rate was assumed to be half of the leak rate for water pipes. The one-dimensional dispersed recharge rates are multiplied by the surface area of each recharge zone to obtain volumetric flow rates, and those are subtotaled by management area.
Figure 5-9 shows a map of average annual dispersed recharge during 1993 to 2007. Although this period does not reflect the most current land use, it is a relatively long averaging period that includes a wide range of year types. Most dispersed recharge occurs during relatively wet years. Average annual recharge rates ranged from less than 0.4 to slightly over 13 inches per year (in/yr). Within the Basin, land use had the largest effect on recharge, with residential land uses having relatively high rates because of landscape irrigation, pipe leaks and percolation of a fraction of the runoff from impervious areas. In tributary watershed areas, partitioning of deep percolation beneath the root zone into stream base flow versus groundwater recharge had a strong influence on simulated recharge. In watersheds on the eastside of the Basin, a higher percentage of deep percolation was assigned to base flow than in watersheds on the west side of the Basin in order to better match observed stream flows.
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5.7.1.2. Percolation from Streams
Inflowsto the stream network in the surface water module of the groundwater model include a combination of gauged flows, and simulated runoff from tributary watersheds and valley floor areas obtained from the rainfall-runoff-recharge model.
The surface water module of the groundwater model simulates percolation reach by reach along each stream that crosses the basin, including Temescal Wash and small streams emanating from 15 watersheds around the periphery of the Basin. Percolation is affected by groundwater levels where the water table is equal to or higher than the elevation of the stream bed. This is sometimes the case along Temescal Wash, but the small tributary streams are mostly high above the water table elevation except up in the canyons where they first enter the Basin.
5.7.1.3. Reclaimed Water Percolation
Reclaimed wastewateris percolated in ponds at the TVWD WRF and the City of Corona’s WRF3. However, most of the reclaimed water is recycled for irrigation. Annual or monthly data describing the partitioning of reclaimed water into irrigation, pond percolation and discharge to Temescal Wash were obtained from TVWD and the City of Corona.
5.7.1.4. Subsurface Groundwater Inflow
Subsurface inflow from an adjacent MA or a neighboring basin is simulated by the groundwater model based on water level gradients and subsurface permeability along the boundary segments. In the Coldwater MA, the only such boundary is the Glen Ivy Fault, and flow across that boundary is almost entirely outward to the Bedford MA. In addition to the Glen Ivy Fault, the Bedford MA receives a small among of subsurface inflow from the Elsinore Subbasin and generates a small amount of outflow to the Temescal Basin. Small amounts of subsurface inflow to both MAs also occurs where they abut upland tributary watersheds.
Recharge in those watersheds flows toward the Basin through fractures in bedrock. This process is simulated by the rainfall-runoff-recharge model.
5.7.1.5.Quarry Recharge
Quarry recharge represents inflows of surface water into existing quarries where it is allowed to recharge into the groundwater. In the Coldwater MA, streamflow from Mayhew Creek and some other smaller streams is directed into existing quarry areas where the water is contained and allowed to percolate. Coldwater Creek has been redirected around an existing quarry. Although Coldwater Creek is not currently directed into a quarry, there have been historic instances where flood flows have gone into the quarries, especially prior to 2005. A portion of the estimated streamflow from the rainfall-runoff-recharge model for each stream is recharged to groundwater at the quarry location.
Similarly, in the Bedford MA, streamflow from Brown and McBride Creeks flows into the Mobile Sand quarry located just north of the TVWD WRF. In addition, streamflow from Temescal Wash can flow into the quarry location especially during high and flood flows. The quarry pit at this location is below the water table and is consistently flooded. To estimate Bedford-Coldwater GSP 5-18
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the recharge, the MODFLOW model applies a boundary condition based on the observed water level in the pit to estimate the volume of quarry recharge.
5.7.2. Outflows from Groundwater
Major outflows from the Basin are groundwater pumping (municipal, industrial, agricultural, and domestic), groundwater discharge into streams, and evapotranspiration by riparian vegetation.
5.7.2.1. Pumping by Wells
Pumping from M&I wells has been measured and recorded for many years by TVWD and Western. Those data are used in the groundwater model. Total pumping for both MAs was about 11,000 (acre feet per year) AFY in the 1990s and decreased to around 3,000 AFY by 2018. This trend was caused by the replacement of groundwater-supplied citrus orchards to urban land usessupplied almost entirely by imported water. In the Bedford MA, TVWD pumps groundwater to supplement recycled water used for irrigation. In the Coldwater MA, groundwater is pumped and exported for municipal use in the Elsinore Subbasin and Temescal Basin by EVMWD and the City of Corona. Pumping is expected to remain around current volumes in the Coldwater MA, consistent with the existing agreement between Corona and EVMWD. However, pumping in the Bedford MA is expected to increase to accommodate future TVWD non-potable water demands.
5.7.2.2. Subsurface Outflow
Subsurface outflows to other MAs or external basins were calculated with the groundwater model by the same methods used to simulate subsurface inflows. The two outflow boundaries are from the Coldwater MA to the Bedford MA and from the Bedford MA to the Temescal Basin. Both of those flows are minor components of the water budget (one to four percent of total outflows).
5.7.2.3. Groundwater Discharge to Streams
Discharges from the Basin to surface water bodies are simulated by the groundwater model based on streambed wetted area, permeability, and on the amount by which the simulated groundwater elevation in a model stream cell is higher than the simulated surface water elevation. This probably occurs at times along Temescal Wash, although dry-season Google Earth aerial photographs rarely show open water in the channel. The groundwater model simulated groundwater discharge to Temescal Wash that averaged 16 percent of total outflow from the Bedford MA during 1993 to 2007.
5.7.2.4. Riparian Evapotranspiration
Evapotranspiration of groundwater by phreatophytic riparian vegetation is influenced by available soil moisture and by depth to the water table. Like other types of vegetation, phreatophytes use soil moisture supplied by rainfall when it is available. Any remaining evapotranspiration demand is met by drawing water from the water table. Phreatophyte use of groundwater is assumed to decrease from the maximum rate when the water table is at Bedford-Coldwater GSP 5-19
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the land surface to zero when the water table is 20 feet or more below the ground surface.
These calculations are applied at all model cells, but non-zero amounts only occur where the depth to water is commonly less than 20 feet. Aerial photographs indicate a correlation between those areas and the presence of dense, lush riparian vegetation.
Riparian evapotranspiration (ET) was a relatively minor component of groundwater outflow in both MAs—averaging four percent of total outflowsfrom the Coldwater MA and 10 percent of total outflows from the Bedford MA.
5.7.2.5.Quarry Operations and Losses
Quarry outflows represents outflows associated with active or passive quarry operations to account for observed water conditions within the deeper quarry pits. In the Coldwater MA, excavations continued within the large quarry pits following periods of high groundwater levels for the period from 1990 to 2010. During model calibration, it was necessary to assume that additional pumping or other groundwater removal occurred during these operational periods to maintain the observed groundwater levels. Since 2010, it is our understanding that no additional pumping to maintain quarry water levels at the elevations necessary for deepening pits has occurred, which is supported by the historical model calibration.
In the Bedford MA, the rim of the Mobile Sand quarry located just north of the TVWD WRF is low enough to allow surface flow between the pit and Temescal Wash when water levels in the pit or Wash are high. To estimate these flows, the groundwater model applies a boundary condition based on the observed water levels in the pit and Wash to estimate the volume of into or out of the pit. This is a head-dependent boundary condition that is able to calculate either quarry recharge or outflow based on groundwater conditions.
5.8. CHANGE IN GROUNDWATER STORAGE
Figure 5-10 showsthe cumulative change in storage from the model for the two Management Areas during 1990 through 2068. The baseline and growth plus climate change scenario results for 2019 to 2068 are displayed as continuations of the historical storage changes from 1990 to 2018.
As shown, groundwater storage in the Bedford MA increased slightly during 1990 to 2018, presumably as a result of the decrease in total groundwater pumping. Consistent with total simulated inflows and outflows, the storage trend during 2019 to 2068 was level to slightly increasing for both future scenarios. Storage was slightly higher during droughts under the growth plus climate change scenario relative to the future baseline scenario. This is because urban recharge continues during droughts. High recharge in wet yearstended to resetstorage for both scenarios to a similar elevation that is partly limited by interaction with Temescal Wash.
Simulated historical storage in the Coldwater MA declined by a cumulative total of 60,000 AF from 1990 to 2004. EVMWD and Corona entered into an agreement to limit pumping in the MA to safe or sustainable yield in 2008 (Corona and EVMWD 2008). As a result, there was Bedford-Coldwater GSP 5-20
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little additional cumulative decline from 2005 to 2018. As a result of decreased pumping, storage under both future scenarios increased steadily from 2019 to 2068. Inflows exceeded outflows in the water budget because of increased urban recharge and continued limitation of pumping. The rate of storage increase was slightly higher under the growth plus climate change scenario relative to the baseline scenario, which can be attributed to increased urban return flow recharge.
5.9. ESTIMATE OF SUSTAINABLE YIELD
The sustainable yield is defined as the volume of pumping that the Basin can sustain without causing undesirable effects. It is not a fixed orinherent natural characteristic of a groundwater basin. Rather, it is influenced by land use activities, importation of water, wastewater and stormwater management methods, potential recharge with recycled water, and the locations of wells with respect to interconnected streams. The estimates ofsustainable yield presented in this section reflect the current status of those variables under the historical and future scenarios and evaluates whether there would be a long-term increase or decrease in basin storage if those conditions continued over a 50-year future period.
A long analysis period is needed to evaluate yield because of the episodic nature of natural recharge. Whereas pumping, irrigation return flow, and pipe leaks are fairly constant from year to year, recharge from precipitation and streams varies widely. Because of evolving land use during 1990 to 2018, no subset of years is ideal for estimating sustainable yield. For the purposes of this GSP historical sustainable yield was calculated based on 1993 to 2017, which is representative of long-term average conditions in terms of precipitation and stream flow.
Sustainable yield was estimated for each management area forthe historicalsimulation (using 1993 to 2017) and the two future simulations (both using all 50 years of the simulation). A simple estimate of sustainable yield can be obtained by adding average annual pumping to average annual change in storage, as shown in Table 5-5.
Table 5-5. Estimated Sustainable Yield
Management Area
Sustainable Yield (acre-feet per year)
Historical
1993 to 20171
Baseline
2019 to 20682
Growth Plus
Climate Change
2019 to 20682
Bedford 1,808 1,419 2,047
Coldwater 4,319 4,581 5,088
Total 6,127 6,000 7,134
1 For the historical sustainable yield estimate, average annual water budgets during 1993 to 2017 were used. 2 The 50-year future simulation uses historical hydrology for 1993 to 2017 two times in succession.
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The baseline simulation generally produces a better estimate ofsustainable yield for planning purposes because it incorporates existing land and water use patterns and a long averaging period that more completely captures climatic and conjunctive use cycles. The sustainable yield under baseline conditions was estimated by the same method used for the historical budget analysis period:simulated average annualstorage change over the 50-year simulation was added to average annual pumping for each MA.
This method of estimating sustainable yield ignores head-dependent responses to pumping in the water budget. In other words, storage change is not the only variable that responds to an increase in pumping. In reality, the response is spread out among storage change, subsurface inflow, subsurface outflow, percolation from streams and groundwater seepage into streams. If those head-dependent boundaries are major parts of the flow system, then an increase in pumping will result in an increase in the estimate of sustainable yield. This boundary interaction effect was not revealed in the Coldwater MA because head-dependent boundary flows there are relatively minor. However, the simulations in the Bedford MA show some variability in sustainable yield as a result of variable pumping in the simulations. The sustainable yield estimates for the Bedford MA understate sustainable yield because of the high degree of interconnection between groundwater and surface water in Temescal Wash.
Additional pumping increases net percolation from the Wash at times when the Wash is flowing. This increase in recharge approximately balances increased pumping, thereby preventing a long-term decrease in storage. This situation results in higher estimates of sustainable yield, as shown in the Bedford MA growth plus climate change sustainable yield in Table 5-5.
The estimates of sustainable yield presented here for the two management areas differ from previous estimates that had different objectives. A previous study of groundwater development potential for the Bedford MA quantified many aspects of the water budget but did not explicitly state an estimated sustainable yield (WEI 2015b). It was asserted that a yield estimate based on historical data would not be representative of future conditions and that future pumping and recharge could strongly affect net percolation from Temescal Wash and therefore also the calculated sustainable yield. The study also did not discuss recharge and pumping related to mining activities, which current modeling shows are important components of the water budget. However, the study recommended that total pumping of no more than 2,000 AFY be implemented in conjunction with water-level monitoring to track the associated long-term changes in storage.
For the Coldwater MA, an estimated yield of 3,300 AFY was the basis of a 2008 agreement between City of Corona and EVMWD regarding sharing of yield (Corona and EVMWD 2008).
This is roughly consistent with pumping and storage change in the current period water budget (Table 5-4), but it is smaller than the yield estimates calculated here for the baseline and growth plus climate change scenarios.
The sustainable yield estimates presented here are the result of a comprehensive review of the historical and future water budget components throughout the Basin. The higher future yield values are the result of increased urban recharge as development progresses in the Basin, as required for SGMA.
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Sustainable yields calculated from the future scenarios are based on projections far into the future. Slight imbalances in estimated water budgets can result in large cumulative changes in storage, and hence in the calculated yields. By the same token, the long planning horizon provides ample time to adjust water management (recharge and pumping) to maintain basin operation within the sustainable yield if long-term rising or falling trends in cumulative storage in fact occur. In the context of this GSP, sustainable yield estimated from the water budget is contingent on the absence of undesirable results related to water levels, storage, subsidence, water quality, or depletion of interconnected surface water. Quantitative sustainability criteria are presented in Section 6 that define thresholds at which groundwater conditions become undesirable for each of those sustainability indicators. For example, if pumping at the above estimates ofsustainable yield caused subsidence or significant impacts on riparian or aquatic habitats, the yield may need to be reduced to avoid those impacts.
Accordingly, this sustainable yield value is a broad indicator. It indicates no overdraft based on the water budget, but it must be interpreted through evaluation of undesirable results.
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6. SUSTAINABLE MANAGEMENT CRITERIA
The Sustainable Groundwater Management Act (SGMA) defines sustainable management as the use and management of groundwaterin a mannerthat can be maintained without causing undesirable results, which are defined as significant and unreasonable effects caused by groundwater conditions occurring throughout the Bedford-Coldwater Subbasin (Basin), which include:
• Chronic lowering of groundwater levels indicating a significant and unreasonable depletion of supply.
• Significant and unreasonable reduction of groundwater storage. • Significant and unreasonable seawater intrusion.
• Significant and unreasonable land subsidence that substantially interferes with surface land uses.
• Significant and unreasonable degraded water quality, including the migration of contaminant plumes that impair water supplies.
• Depletions of interconnected surface water that have significant and unreasonable adverse impacts on beneficial uses of the surface water.
For these sustainability indicators5
, a Groundwater Sustainability Plan (GSP) must develop
quantitative sustainability criteria that allow the Groundwater Sustainability Agency (GSA) to define, measure, and track sustainable management. These criteria include the following:
• Undesirable Result – significant and unreasonable conditions for any of the six sustainability indicators.
• Minimum Threshold (MT6
) – numeric value used to define undesirable results for each sustainability indicator.
• Measurable Objective (MO) – specific, quantifiable goal to track the performance of sustainable management.
Together, these sustainability criteria provide a framework to define sustainable management and delineate between favorable and unfavorable groundwater conditions. This framework also supports quantitative tracking that identifies problems promptly, allows assessment of management actions, and demonstrates progress in achieving the goal of sustainability.
5 If one or more undesirable results can be demonstrated as not present and not likely to occur, a GSA is not required to establish the respective sustainability criteria per GSP Regulations §354.26(d); in the inland Bedford-Coldwater Basin (Basin) seawater intrusion is not present and not likely to occur. 6 The abbreviations for Minimum Threshold (MT) and Measurable Objective (MO) are provided because these terms are used often; however, the full unabbreviated term is used when helpful for clarity or when included in a quotation.
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6.1. SUSTAINABILITY GOAL
The sustainability goal can be described as the mission statement of the GSA for managing the Basin; it embodies the purpose of sustainably managing groundwater resources and reflects the local community’s values—economic, social, and environmental. The sustainability goal for the Basin, stated below, was developed through discussion at several GSA meetings.
6.1.1. Description of Sustainability Goal
The goal of the GSA in preparing this GSP is to sustain groundwater resources for the current and future beneficial uses of the Bedford-Coldwater Basin in a manner that is adaptive and responsive to the following objectives:
• Provide a long-term, reliable and efficient groundwater supply for municipal, industrial, and other uses;
• Provide reliable storage for water supply resilience during droughts and shortages; • Protect groundwater quality;
• Support beneficial uses of interconnected surface waters; and • Support integrated and cooperative water resource management.
This goal is consistent with SGMA and is based on information from the Plan Area, Hydrogeologic Conceptual Model, Groundwater Conditions, and Water Budget sections that:
• Identify beneficial uses of Basin groundwater and document the roles of local water and land use agencies;
• Describe the local hydrogeologic setting, groundwater quality conditions, groundwater levels and storage, and inflows and outflows of the Basin; and • Document the ongoing water resource monitoring and conjunctive management of groundwater, local surface water, recycled water and especially imported water sources that help protect groundwater quality and maintain water supply.
6.1.2. Approach to Sustainability Indicators
The approach to assessing the sustainability indicators and setting the sustainability criteria has been based on:
• Review of available information from the Plan Area, Hydrogeologic Conceptual Model, Groundwater Conditions, and Water Budget sections of the GSP. • Discussions with Bedford-Coldwater stakeholders and local agency representatives, GSA manager meetings, and workshops.
This approach has developed throughout the process and generally began with definition of what an undesirable result is; this initially has been exploratory and qualitative and based on plain-language understanding of what undesirable means. Potential minimum thresholds Bedford-Coldwater GSP 6-3
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have been explored in terms of when, where, how long, why, under what circumstances, and what beneficial use is adversely affected. This step identified seawater intrusion as not present and not likely to occur.
Beyond a qualitative identification of what is undesirable, the approach to defining sustainability indicators varies among the undesirable results. Several of the undesirable results are directly or indirectly related to groundwater levels, including conditions related to groundwater storage, subsidence, and interconnected surface water. The definition began in terms of groundwater levels in individual wells but has recognized that storage depletion, subsidence, and impacts on connected surface water occur as waterlevels decline. As a result, the sustainability criteria for those indicators are interrelated across space and time, and are coordinated, consistent, and reasonable based on the available data.
The consideration of the causes and circumstances of undesirable results is an important one in Bedford-Coldwater as multiple agencies rely on this small Basin. Water is produced and used in the Basin by Temescal Valley Water District (TVWD) and produced for use in the Basin and in the neighboring Temescal and Elsinore Basins by the City of Corona (Corona) and Elsinore Valley Municipal Water District (EVMWD), respectively. Cooperative groundwater management between these three major agencies is essential to ensure sustainability.
The intent is to quantify and qualify sustainability criteria such that they guide good management without setting off false alarms or triggering costly, ineffective, or harmful management actions.
6.1.3. Summary of Sustainable Management Criteria
This section documents the six sustainability criteria as relevant to Bedford-Coldwater Basin and as guided by the Sustainability Goal. As documented in this section, the Basin has been and is being managed sustainably relative to all criteria (except seawater intrusion, which does not apply because the Basin is over 20 miles from the ocean). Accordingly, sustainability does not need to be achieved, but it does need to be maintained through the planning and implementation horizon. This will involve continuation and improvement of existing management actions. It also will include improvement and expansion of management actions and monitoring. These improvements are addressed for each sustainability criterion specific subsections.
While the Bedford-Coldwater Basin has been managed sustainably, the following sustainability criteria are defined in this section because potential exists for future undesirable results.
• The Minimum Threshold for defining undesirable results relative to chronic lowering of groundwater levels is defined at each Key Well by operational considerations to maintain water levels at or above current pump intakes or screen bottoms (whichever is higher) in municipal water supply wells. Undesirable results are indicated when two consecutive exceedances occur in each of two consecutive Bedford-Coldwater GSP 6-4
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years, in two-thirds or more of the currently monitored wells in each Management Area.
• The Minimum Threshold for reduction of groundwater storage for all Management Areas is fulfilled by the minimum threshold for groundwater levels as proxy. • The Minimum Threshold for land subsidence is defined as a cumulative decline equal to or greater than one foot of decline since 2015, which represents current conditions and the SGMA start date. This is equivalent to a rate of decline equal to or greater than 0.2 feet in any five-year period. The extent of cumulative subsidence across the Basin will be monitored and evaluated using Interferometric Synthetic Aperture Radar (InSAR) data available through the SGMA Data Viewer during the 5- year GSP updates. Subsidence as a result of groundwater elevation decline is closely linked to groundwater levels and it is unlikely that significant inelastic subsidence would occur if groundwater levels remain above their minimum thresholds. • The Minimum Thresholds for degradation of water quality address nitrate and total dissolved solids (TDS) for the entire Basin.
o The Nitrate Minimum Threshold (in both Management Areas) is defined as 5-year average concentrations of all monitored wells not exceeding the 10 milligrams per liter (mg/L) drinking water maximum contaminant level (MCL) for Nitrate as Nitrogen.
o The TDS Minimum Threshold (in both Management Areas) is defined as the 5-year average concentrations not exceeding the 1,000 mg/L secondary MCL for TDS.
• The Minimum Threshold for depletion of interconnected surface water is the amount of depletion associated with the lowest water levels recorded during the 2010 to 2015 drought. Specifically, undesirable results would occur if more than half of monitored wells near Temescal Wash had static water levels lower than 35 feet below the adjacent riparian vegetation ground surface elevation for a period of more than one year.
6.2. CHRONIC LOWERING OF GROUNDWATER LEVELS
Chronic lowering of groundwater levels can indicate significant and unreasonable depletion of supply, causing undesirable results to domestic, agricultural, or municipal groundwater users if continued over the planning and implementation horizon. As a clarification, droughtrelated groundwater level declines are not considered chronic if groundwater recharge and discharge are managed such that groundwater levels recover fully during non-drought periods.
Declining groundwater levels directly relate to other potential undesirable effects (for example regarding groundwaterstorage, land subsidence and interconnected surface water); these are described in subsequent criterion specific sections.
Groundwater elevation trends in the Basin are represented by hydrographs documented in Groundwater Conditions Section 4.1. Over time, groundwater elevations have varied in response to precipitation, groundwater pumping, and groundwater use trends; however, the Bedford-Coldwater GSP 6-5
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Basin does not display widespread chronic groundwater level declines and is not characterized by overdraft.
6.2.1. Description of Undesirable Results
As groundwater levels decline in a well, a sequence of increasingly severe undesirable results will occur. These include an increase in pumping costs and a decrease in pump output. With further declines, the pump may break suction, which means that the water level in the well has dropped to the level of the pump intake. This can be remedied by lowering the pump inside the well, which can cost thousands of dollars. Chronically declining water levels will eventually drop below the top of the well screen. This exposes the screen to air, which can produce two adverse effects. Water entering the well at the top of the screen will cascade down the inside of the well, and entraining air may result in cavitation damage to the pump.
The other potential adverse effect of exposure to air is accelerated corrosion of the well screen. Over time, corrosion creates a risk of well screen collapse, which often renders the well unusable. If water levels decline by more than about half of the total thickness of the aquifer (or total length of well screen), water might not be able to flow into the well at the desired rate regardless of the capacity or depth setting of the pump. This might occur where the thickness of basin fill materials is relatively thin. While describing a progression of potential adverse effects, at some point the well no longer fulfills its water supply purpose and is deemed to have “gone dry.” For the purposes of this discussion, a well going dry means that the entire screen length (to the bottom of the deepest screen) is unsaturated.
For purposes of setting a Minimum Threshold, undesirable results are defined as a well going dry. This appears to be a low standard and not protective of private wells but there are very few private wells in the Basin. The rationale is summarized as follows with more explanation in the following sections:
• There are very few active private wells in the Basin, as residential users are connected to municipal water supplies. The BCGSA is aware of a small number of private wells used for non-potable supply in the Basin. A systematic well inventory identifying all active private wells will be conducted to locate active wells and identify their uses, as described in Section 8.7. This project was designed to locate and characterize the construction and use of existing private wells so that they can be included in sustainable management of the Basin.
• Known private wells are for non-potable uses and are of similar depths and construction to the monitored municipal supply wells. No private wells have been reported to have water shortages in the California Department of Water Resources (DWR) led Household Water Supply Shortage Reporting System (DWR 2021). • Responsibility for potential undesirable results to shallow wells is shared between a GSA and a well owner; there is a reasonable expectation that a well owner would construct, maintain, and operate the well to provide its expected yield over the well’s life span, including droughts.
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6.2.2. Potential Causes of Undesirable Results
For Bedford-Coldwater Basin, the primary potential cause of declining groundwater levels and associated undesirable results would be increased groundwater production and/or reduced inflows (recharge). Given that the Bedford-Coldwater Basin is not characterized by basin-wide chronic groundwater level declines, then the undesirable results of a well losing yield, having damage, or “going dry” represent a more complex interplay of causes and shared responsibility.
Some of the potential causes are within the Bedford-Coldwater Groundwater Sustainability Agency (BCGSA) responsibility; most notably, a GSA is responsible for groundwater basin management without causing undesirable results such as chronic groundwater level declines.
SGMA also requires that a GSA address significant and unreasonable effects caused by groundwater conditions throughout the basin. This indicates that a GSA is not solely responsible for local or well-specific problems and furthermore that responsibility is shared with a well owner. A reasonable expectation exists that a well owner would construct, maintain, and operate the well to provide its expected yield over the well’slife span, including droughts, and with some anticipation that neighbors also might construct wells (consistent with land use and well permitting policies).
6.2.3. Definition of Undesirable Results
As context, the Bedford-Coldwater Sustainability Goal has the objective to provide a longterm, reliable, and efficient groundwater supply for municipal, industrial, and other uses.
In that light, the definition of undesirable results would be the chronic lowering of groundwater levels indicating a significant and unreasonable depletion of supply if continued over the planning and implementation horizon. This is defined by groundwater conditions occurring throughout the Basin, with a focus on operation of wells. This definition also recognizes that chronic lowering of groundwater levels could affect groundwater flow to or from the hydraulically connected Temescal and Elsinore Basins, and thereby potentially affect their ability to maintain sustainability.
As documented in Groundwater Conditions Section 4.1, analysis of hydrographs reveals that Bedford-Coldwater is not characterized by basin-wide chronic groundwater level declines.
While affected at times by drought, groundwater levels in broad areas of the Basin have been maintained at relatively stable levels. Moreover, the Bedford-Coldwater area has not been marked by reports of significant impacts to shallow supply wells as a result of water level declines. In the absence of reported well problems associated with declining groundwater levels, it can be concluded that undesirable results for the chronic lowering of water levels are not occurring in the Bedford-Coldwater and that the Basin is managed sustainably relative to groundwater levels.
Bedford-Coldwater GSP 6-7
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6.2.4. Potential Effects on Beneficial Uses and Users
Groundwater is a source of supply in the Basin and supplies water for municipal, industrial, and other beneficial uses. Groundwater has been and is being used for the range of beneficial uses, even during drought, and with reasonable operation and maintenance by well owners.
6.2.5. Sustainable Management Criteria for Groundwater Levels The general approach to defining sustainability criteria (minimum thresholds and measurable objectives) for groundwater levels has involved selection of representative monitoring wells, review of groundwater level data, and review of supply well location/construction information to gage potential undesirable effects on wells. Specifically, this has included evaluating historical water levels and well operations in monitored wells. This approach is founded on the idea that undesirable results are the reduction of available supply in these monitored wells.
6.2.5.1. Selection of MT by Well
The approach includes selection of existing wells currently monitored in the Basin.
Sustainability criteria would be defined for each of these wells, and each would be monitored for groundwater levels with respect to MTs and MOs. These wells are primarily production wells, which is not optimal for monitoring because pumping lowers water levels resulting in monitoring that is sometimes not representative of aquifer conditions. On the other hand, they are generally representative of production wells throughout the Basin.
Groundwater level data and hydrographs of each monitored well have been reviewed along with well construction and pumping equipment details in each monitored well. These data were used to review wellsthat the BCGSA currently monitorsto confirm that they are suitable for use as Key Wells for defining MTs and MOs. This process showed that all the wells that the BCGSA agencies currently monitor are appropriate for use as Key Wells and monitoring of these wells will continue in the future. Table 6-1 shows information on the Key Wells in the Basin. The table also shows well construction and pump intake information along with maximum historical depth to water and well-specific MT. The locations of the Key Wells are shown on Figure 6-1.
Table 6-1. Minimum Thresholds for Groundwater Levels
Local Well Name Agency Management Area Monitoring Frequency Total Well Depth
(feet)
Screen Interval
Depths (feet)
Pump Intake
Depth (feet)
Historical Maximum
Depth to Water (feet)
Date of Maximum
Depth to Water
Threshold
Description
Threshold Depth to
Water (feet)
Corona Well 20 Corona Coldwater Static - Monthly 660 200 to 580 460 375.10 1/17/2017 Pump intake 460 Corona Well 21 Corona Coldwater Static - Monthly 660 200 to 580 460 398.00 12/1/2001 Pump intake 460 Corona Well 3 Corona Coldwater Static - Monthly 543 100 to 530 479 392.00 12/16/2016 Pump intake 479 Corona Non-Potable Well 1 Corona Bedford Continuous (SCADA) Unkown Unkown Unkown 55.60 11/13/2016 Nearby pump intake 80 Corona Non-Potable Well 2 Corona Bedford Continuous (SCADA) Unkown Unkown Unkown 55.40 11/13/2016 Nearby pump intake 80 EVMWD Flagler 2A Well EVMWD Bedford Continuous (SCADA) 105 51 to 92 80 48.00 10/18/2019 Pump intake 80 EVMWD Flagler 3A Well EVMWD Bedford Continuous (SCADA) 100 51 to 90 80 57.00 10/18/2019 Pump intake 80 Corona & EVMWD Trilogy EVMWD Coldwater Quarterly 579
250 to 360 and 390 to
450 No pump 359.30 10/12/2016
Ten feet above bottom
of screen 440
EVMWD Station 71 EVMWD Bedford Quarterly 600 239 to 588 507 499.92 7/21/2017 Pump intake 507 EVMWD Mayhew Well 2 EVMWD Coldwater Quarterly 740 300 to 730 507 440.99 11/28/2017 Pump intake 507 TVWD Well 1 (Old well) TVWD Bedford Continuous (SCADA) 100 40 to 80 No pump 42.50 11/1/2016 Ten feet above bottom
of screen 70
TVWD Well 1A TVWD Bedford Continuous (SCADA) 100 40 to 80 85 53.40 11/15/2016 Ten feet above bottom
of screen 70
TVWD Well 4 TVWD Bedford Continuous (SCADA) 100 40 to 80 85 46.80 10/7/2015 Ten feet above bottom
of screen 70
TVWD TP-1 TVWD Bedford Continuous (SCADA) 103 39 to 99 85 Unknown Unknown Pump intake 85 TVWD TP-2 TVWD Bedford Continuous (SCADA) 90 30 to 85 85 Unknown Unknown Ten feet above bottom
of screen 75
TVWD Foster TVWD Bedford Continuous (SCADA) 93 38 to 88 84 Unknown Unknown Ten feet above bottom
of screen 78
TVWD New Sump TVWD Bedford Continuous (SCADA) 74 Unkown 66 101.67 8/1/1994 Pump intake 66 T:\Projects\Bedford Coldwater GSP 80802\Deliverables\GSP\6 Sustainability Criteria\Sustainability Tables v2.xlsx - WL Summary Todd Groundwater Des by: MR
Ckd by: CT
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6.2.6. Minimum Thresholds
According to GSP Regulations Section 354.28(c)(1), the minimum threshold for chronic lowering of groundwater levels must be the groundwater elevation indicating a depletion of supply at a given location that may lead to undesirable results. MTs for chronic lowering of groundwater levels are to be supported by information on the rate of groundwater elevation decline based on historical trends, water year type, and projected water use in the Basin.
However, as documented in the Groundwater Conditions Section 4.1.3, groundwater levels are not chronically declining in Bedford-Coldwater. While groundwater levels decline in dry and critically-dry years, they have recovered in normal, above normal, and wet years.
Groundwater levels in some wells were at historical lows after the recent drought ending in 2016 but are recovering.
Currently, none of the wells have groundwater levels below their respective MTs and no undesirable results are known to have occurred in the past. Nonetheless, MTs have been developed because the potential exists for chronic lowering of groundwater levels in the future.
Using available recent and reliable information on the construction of existing supply wells, the MT levelsshown in Table 6-1 are protective of mostsupply wells. Based on historical lows, the MTs account for historical groundwater level variations, and consideration has been given to supporting Basin management flexibility, for example to avoid setting off false alarms or triggering costly, ineffective, or harmful management actions.
The MTs shown in Table 6-1 were developed making use of available data. However, uncertainties exist as summarized below:
• The geographic distribution of wells in the groundwater level monitoring program is uneven.
• Information on vertical groundwater gradients is lacking and groundwater levels in shallow wells may not be represented adequately by relatively deep wells. • The specific location, status, and construction of most existing private wells is not known, or the information is not readily available (in databases).
These uncertainties have been recognized and are being addressed in this GSP as follows:
• Mapping and prioritization of geographic gaps in the monitoring program. • Installation of two new dedicated monitoring wells sited and designed to support the groundwater level monitoring program (among other objectives) and to become Key Wells.
• Identification and mapping of existing active private production wells within the Basin, as described in Section 8 Projects and Management Actions.
The benefits of these efforts will accrue over the next few years and will support review and update of the MTs in the 5-Year GSP Update in 2027.
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6.2.6.1. Minimum Thresholds and Criteria for Undesirable Results Undesirable results are based on exceedances of MT levels and must be defined not only in terms of how they occur (as described in Section 6.2.2 Potential Causes of Undesirable Results), but also when and where. By definition, undesirable results are not just droughtrelated but chronic and are not just local but basin-wide.
The distinction between drought and chronic declines may not be clear when declines are occurring, particularly during drought when it is not known whether subsequent years will bring recovery. Moreover, effects of declining levels on individual well owners may be real problems, whether or not they represent basin-wide sustainability issues.
The BCGSA will perform quarterly or more frequent groundwater level monitoring.
Accordingly, groundwater level monitoring and annual reporting provides an early warning system that allows response by the BCGSA and local groundwater users. From this perspective, two consecutive exceedances in each of two consecutive years is regarded as indicating when an undesirable result is occurring. The exceedances would be measured at a Key Well as part of the regular quarterly monitoring program. It should be noted that GSA responses do not have to wait for two years and may involve a staged response as in urban water shortage contingency plans.
While undesirable results relate to groundwater conditions throughout the Basin, the Basin has been organized into two management areas (MAs). As discussed in Section 5.4, this reflects the fact that the Basin is separated by a fault zone, limiting (but not eliminating) flow between the two MAs. Groundwater level MTs will be evaluated separately for each MA, because the groundwater histories are distinct, albeit linked. As a result, undesirable results could occur in one MA and not the other. Accordingly, undesirable results are indicated to be occurring when two-thirds or more of the currently monitored wells in the MA have had two consecutive exceedances in each of two consecutive years.
To summarize for the Bedford-Coldwater Basin:
The Minimum Threshold for defining undesirable results relative to chronic lowering of groundwater levels is defined at each Key Well by operational considerations to maintain waterlevels at or above current pump intakes orscreen bottoms(whichever is higher) in municipal watersupply wells. Undesirable results are indicated when two consecutive exceedances occur in each of two consecutive years, in two-thirds or more of the currently monitored wells in each Management Area.
6.2.6.2. Relationship of Minimum Threshold to Other Sustainability Indicators The establishment of MTs also needs to consider potential effects on other sustainability indicators. These indicators are discussed later in this section; the following are brief discussions.
• Groundwater Storage. The MTs for groundwater levels are protective of groundwater storage. These MTs are defined in terms of operational considerations Bedford-Coldwater GSP 6-11
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for wells used to support beneficial uses in the Basin. The major concern expressed in the Sustainability Goal is to have reliable storage for drought conditions. As the water level MTs support maintenance of production capacity in wells, they also support maintenance of reliable storage.
• Seawater Intrusion. There is no possibility of seawater intrusion in the BedfordColdwater Basin as it is more than 20 miles from the ocean. Accordingly, there is no seawater intrusion minimum threshold and no relationship with other minimum thresholds.
• Subsidence. Subsidence is linked to groundwater levels. It is unlikely that significant inelastic subsidence would occur if groundwater levels remain within the operational range of water levels, which have been used to define groundwater level MTs. Accordingly, the minimum threshold for groundwater levels is consistent with and supportive of the objective to prevent subsidence undesirable results. • Water Quality. General relationships are recognized, for example that contaminants may be mobilized by changing groundwater levels or flow patterns. Maintenance of groundwater levels within historical operational ranges would minimize any effects on maintenance of water quality at or above minimum thresholds. The groundwater quality issues in Bedford-Coldwater Basin are associated primarily with salt and nutrient loading and not likely to be affected by groundwater levels or flow within operational ranges.
• Interconnected Surface Water. The set of monitoring wells used to evaluate interconnected surface water overlaps with the set of wells used for the groundwater levels minimum threshold. In general, the MTs for interconnected surface water are similar to or higher than those for groundwater levels; the higher MTs would be controlling.
6.2.6.3. Effect of Minimum Threshold on Sustainability in Adjacent Areas The Bedford-Coldwater Basin is adjacent to the Temescal Basin and the Elsinore Basin.
Groundwater flow directions are from the Elsinore Basin through Bedford MA to the Temescal Basin with some drainage into the Temescal Wash. The Bedford-Coldwater groundwater level MTs would support maintenance of groundwaterlevels above theirrespective MTsin Bedford MA. This in turn will support maintenance of groundwater levels in the Temescal Basin.
6.2.6.4. Effect of Minimum Threshold on Beneficial Uses and Users Groundwater is the major source of supply in the GSP Area and supplies wells for municipal, industrial, and other beneficial uses and users. The MTs are based generally on well operations, which recognizes that groundwater has been and is being used reasonably for the range of beneficial uses even during drought, and with reasonable operation and maintenance by well owners. The MTs quantify undesirable results as involving two-thirds of wells in a MA with two consecutive exceedances in each of two consecutive years, which provides early warning of declining groundwater levels.
While there are a small number of private wells in the Basin, there are no DACs or SDACs in the Basin and the only private domestic well in the Basin belongs to the Glenn Ivy Hot Springs.
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The BCGSA believes that all other private wells in the Basin are used for non-potable supply.
Project 2 (described in Section 8.7) is designed to locate and characterize the construction and use of all existing active private wells to ensure that the minimum threshold for groundwater levels is protective of all users in the Basin, recognizing the human right to water.
6.2.6.5. Relationship of Minimum Threshold to Regulatory Standards No federal, state or local standards exist for groundwater levels.
6.2.6.6. How Management Areas Can Operate without Causing Undesirable Results The establishment of MTs has been consistently conceived and applied across both Management Areas. MTs are based on well operations, which vary from well to well representing local conditions that do not necessarily occur at the same time across the MAs.
Maintenance of water levels within the operational range in wells is not anticipated to cause undesirable results between the two MAs.
6.2.6.7. How the Minimum Threshold will be Monitored
Monitoring for the groundwater levels MT will be conducted as part of the BCGSA groundwater level monitoring program, data and analytical results will be presented in the Annual GSP Reports. The BCGSA monitoring program includes wells monitored by Corona, EVMWD, and TVWD.
6.2.7. Measurable Objectives
Measurable Objectives are defined herein as an operating range of groundwater levels, allowing reasonable fluctuations with changing hydrologic and surface water supply conditions and with conjunctive management of imported water and groundwater. The groundwater level MTs represent the bottom of the operating range and are protective of groundwater users. The top of the operating range is generally where the water table approaches the soil zone and ground surface, except where groundwater and surface water are interconnected or groundwater dependent ecosystems exist. Section 6.7 addresses these areas and potential undesirable results with Depletions of Interconnected Surface Water.
With these important exceptions, the top of the operating range is below the soil zone, thereby minimizing potential agricultural drainage problems.
The Measurable Objective is to maintain groundwater levels above the historical maximum depth to groundwater, and to maintain groundwater levels within the operating range as defined in this section.
Groundwater conditions with respect to chronic groundwater level declines are already sustainable. Therefore, no interim milestones are needed to achieve sustainability by 2042.
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6.2.7.1. Discussion of Monitoring and Management Measures to be Implemented Data gaps and sources uncertainties have been identified in this section, including the lack of reliable and accessible information on active private well pumping and construction.
Management actions to maintain groundwater levels have been ongoing and effective for decades. These actions (consistent with the Sustainability Goal objective to support integrated and cooperative water resource management) have included acquiring imported water for direct use, providing recycled water for irrigation, and other conjunctive use operations. The BCGSA will also implement management actions to inventory existing active private wells. This will include identification of locations and construction information for active wells throughout the Basin to support refinement of the groundwater level MTs and MOs in the 5-year GSP update.
Monitoring improvements are discussed in Section 7, including results of the Dedicated Monitoring Well Program initiated in June 2020.
6.3. REDUCTION OF GROUNDWATER STORAGE
Groundwater storage is the volume of water in the Basin and provides a reserve for droughts orsurface watersupply shortages. The MT forreduction of groundwaterstorage isthe volume of groundwater that can be withdrawn from a Basin or MA without leading to undesirable results. Undesirable results would involve insufficient stored groundwater to sustain beneficial uses throughout drought or water supply shortage. The storage criteria are closely linked to groundwater levels. The sustainability indicator for groundwater storage addresses the ability of the groundwater Basin to support existing and planned beneficial uses of groundwater, even during drought and surface water supply shortage.
For the each of the two MAs of the Bedford-Coldwater Basin, the water budget has been calculated using the numerical model, as described in Water Budget Section 5. In brief, this has included analyses of the cumulative change in storage for each of the two MAs for the historical and current period, 1990 through 2018, and for simulated future conditions (see Figures 5-5 and 5-6). The water budget analyses have shown the dynamic effects of drought and changes in groundwater use and indicate that groundwater storage in the Basin has been sustainably managed relative to storage. The water budget inflow and outflows have been balanced over the long term. Furthermore, as indicated in Section 6.2, none of the water supply wells have been reported as going dry in the Basin during the historical period of record.
6.3.1. Description of Undesirable Results
Given that Bedford-Coldwater Basin has not experienced any impacts to wells related to groundwater storage, the undesirable result associated would be an insufficient supply to support beneficial uses during droughts. Storage is related to groundwater levels. Thus, undesirable results associated with storage would likely be accompanied by one or more Bedford-Coldwater GSP 6-14
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undesirable results associated with groundwater levels, including reduced well yields, subsidence, and depletion of interconnected surface water.
6.3.2. Potential Causes of Undesirable Results
For groundwater storage in the Basin, the basic cause of undesirable results would be an imbalance of the water budget, such that outflows exceed inflows resulting in reduction of groundwater storage. This imbalance could be caused in turn by reduced surface water supplies and associated groundwater recharge. Such reduction could potentially include the following conditions: 1) increased pumping due to disruption of imported water, 2) reduced percolation from Temescal Wash, 3) reduced natural recharge due to increased impervious area (development), or 4) increased pumping due to reduced recycled/non potable discharge and use. Undesirable results also could occur because of changes in land use causing increased demand for groundwater; this would be most problematic in portions of the Basin without access to other water supplies.
6.3.3. Definition of Undesirable Results
Undesirable results are defined with the understanding that the objective of groundwater management is to provide reliable storage for water supply resilience during droughts and shortages. Accordingly, the definition of potential undesirable results for storage reduction includes consideration of how much storage has been used historically (i.e., operating storage) and how much stored groundwater reserve is needed to withstand droughts.
In considering conceptual operating storage or groundwater reserves, it is important to bear in mind that these are not the total amount of groundwater that could potentially be extracted from the Basin. Most wells are in the range of 75 to 700 feet deep.
The depth of the Basin ranges from less than 40 feet in some areas to more than 800 feet in others (see Figure 3-9). Groundwater wells used for water supply are generally located in the deeper portions of the Basin. Additional groundwater storage could be utilized, with the foremost assumption that withdrawals and reduction are followed by commensurate recharge and recovery. This could occur as part of enhanced conjunctive use programs.
6.3.4. Potential Effects on Beneficial Uses and Users
Groundwater is a source of water supply in the GSP Area and supplies wells for municipal, industrial, and other beneficial uses. Reduction of groundwater storage would reduce access to that supply with adverse effects on the community, economy, and environmental setting of the Temescal Valley. However, groundwater has been and is being used for the beneficial uses, even during drought.
6.3.5. Sustainable Management Criteria for Groundwater Storage The general approach to defining sustainability criteria for groundwater storage has involved review of historical cumulative change in storage and expected future storage declines during Bedford-Coldwater GSP 6-15
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droughts. Review of historical change in storage is useful to estimate about how much storage has been used in each Management Area, effectively defining an operating storage. Similarly, the approach focuses on the beneficial uses of the Basin and acknowledges much of the pumping occurs in larger municipal wells with dynamic operations. Sustainability criteria for groundwater levels also take into account historical ranges and the management of dynamic operation of municipal wells.
6.3.5.1. Description of Historical Cumulative Change in Storage: 1990 through 2018 The cumulative change in storage by management area for historical and current conditions (1990 through 2018) as simulated by the numerical model is discussed and shown in tables and figures in Section 5. Observations about the historical operating storage for each of the Management Areas are as follows:
Bedford Management Area. The average annual change in groundwater storage was stable over the model period, 1990 through 2018, with an average increase in storage of 73 acrefeet per year (AFY). This increase in storage is due to decreased pumping from 2005 to the end 2019, when pumping in the MA averaged about 1,000 AFY. The change in storage during this same period increased on average about 400 AFY. For the early portion of the model (1990 through 2004), groundwater pumping was approximately 2,500 AFY, which resulted in a slight decline in groundwater storage. The average annual decrease in storage during this period was 22 AFY. This storage response indicates the Basin can support this range of operation, given appropriate natural recharge. Groundwater storage has increased a total of 2,215 acre-feet (AF) over the model period. The simulated increasing trend of groundwater storage in this MA provides an operational range that would support beneficial uses.
Coldwater Management Area. The average annual change in groundwater storage over the model period was an average annual decrease of about 2,000 AFY. Declines in storage in this MA were more pronounced early in the model period, averaging over 3,800 AFY between 1990 and 2004. Recent groundwater storage change has been relatively stable even with a significant drought period from 2014 to 2017. The local agencies pumping from the Coldwater MA have agreed to limit their pumping to a sustainable yield volume based on available recharge. Accordingly, groundwater pumping has declined from an average of over 6,500 AFY between 1990 and 2008 to approximately 3,000 AFY from 2009 through 2018. In the Coldwater MA, the simulated groundwater storage stabilized and largely recovered during the one to two years following droughts, but still showed a general decrease in groundwater storage due to increased groundwater production over the model period. Given the storage stability in the current period (2008 through 2018) and current groundwater management practices, groundwater storage will likely continue to increase on average and recover from short term droughts on the order of one to two years. These groundwater management practicesinclude the existing agreement between local agenciesto pump within a sustainable yield.
Ongoing aggregate mining in the Coldwater MA (and to a lesser extent Bedford MA) may impact both the inflows and outflows used to calculate the change in storage. Uncertainty exists about the role in storage changes of open pits used in quarry operations, specifically Bedford-Coldwater GSP 6-16
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their contribution to additional recharge in wet years and/or additional outflow through evaporation or other processes. A potential management action to collect additional data related to quarry operations is discussed in Section 8.
6.3.6. Minimum Threshold
Undesirable results relative to groundwater storage have not occurred in the Basin and numerical modeling of future conditions indicate that groundwater storage can continue to be operated within historical limits. However, given the dynamic nature of the BedfordColdwater production wells, additionalstorage outside of the historical limits may be needed.
According to SGMA, the minimum threshold for storage is to be defined as the maximum groundwater volume that can be withdrawn without leading to undesirable results.
GSP Regulations allow the use of the groundwater level sustainability criteria (MTs and MOs) as a proxy for groundwater storage, provided that the GSP demonstrates a correlation between groundwater levels and storage. Groundwater levels and storage are directly related. This is demonstrated by comparison of groundwater level and storage trends, which reveal the same patterns of changes in pumping, response to drought, and recovery, as discussed in Section 5. The relationship of groundwater levels and storage is embodied in the calibrated numerical model.
The rationale for using groundwater levels as a proxy metric for groundwater storage is that the groundwater level MTs and MOs are sufficiently protective to prevent significant and unreasonable results relating to storage. Groundwater level MTs have been defined to protect supply wells (see Section 6.2.6) and are based on the following:
• A broad geographic distribution of Key Wells that are representative of production wells in the Basin;
• MTs that are based on operational parameters for existing water supply wells; • Analysis of existing municipal supply wells with construction information and setting of MTs to avoid operational failure in these wells; and • Groundwater level MTs that include two consecutive quarters in two years, providing early warning for storage changes, while also involving two-thirds or more of the Key Wells in each MA, thus involving a broad area, consistent with storage change.
As a practical matter, the availability of groundwater in storage will be constrained by MTs for water levels (including groundwater level proxies for depletion of interconnected surface water). The MTsfor groundwater levels will be sufficiently protective of groundwaterstorage.
To summarize for the Bedford-Coldwater Basin:
The Minimum Threshold for reduction of groundwater storage for all MAs is fulfilled by the minimum threshold for groundwater levels. The Minimum Threshold for defining undesirable results relative to chronic lowering of groundwater levels is Bedford-Coldwater GSP 6-17
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defined at each Key Well (two consecutive quarters in two years, providing early warning for storage changes, in two-thirds or more of the Key Wells in each MA).
The Sustainability Goal for the Bedford-Coldwater Basin includes an objective to provide reliable storage for water supply resilience during droughts and shortages. Use of groundwater levels as a proxy also fulfills that objective. No additional MT definition is needed.
6.3.6.1. Relationship of Minimum Threshold to Other Sustainability Indicators • Water Levels. The minimum thresholds for groundwater levels are protective of the beneficial use of the Basin – municipal, industrial, and other water supply; therefore, these levels are protective of and serve as a proxy for groundwater storage and the provision of reliable storage for drought and shortage. • Seawater Intrusion. There is no possibility of seawater intrusion in BedfordColdwater Basin. Accordingly, there is no minimum threshold and no relationship with other minimum thresholds.
• Subsidence. Subsidence is linked to groundwater levels. Because the storage reduction minimum threshold would not cause water levels to drop below their minimum thresholds, it would not interfere with the subsidence minimum threshold.
• Water Quality. Maintenance of groundwater storage within historical and operational ranges would minimize any effects on water quality relative to water quality minimum thresholds. Groundwater quality issues in Bedford-Coldwater Basin are associated primarily with salt and nutrient loading and not likely to be affected by groundwater storage within historical and operational ranges. • Interconnected Surface Water. The minimum thresholds for depletion of surface water flow are linked to groundwater levels near stream reaches with shallow groundwater. Those water levels are generally equal to or higher than the minimum thresholds for water levels in those areas. Thus, it is likely that the interconnected surface water threshold would constrain storage utilization.
6.3.6.2. Effect of Minimum Threshold on Sustainability in Adjacent Areas The Bedford-Coldwater Basin is located downstream from the Elsinore Valley Subbasin along Temescal Wash. Groundwater flow directions are from the Elsinore Valley Subbasin to the Bedford-Coldwater Basin. The groundwater level MTs for the Bedford-Coldwater Basin would support maintenance of groundwater levels and storage within the operational range in the Bedford MA adjacent to the Elsinore Valley Subbasin. This in turn will support maintenance of operational groundwater storage in the neighboring Elsinore Valley Subbasin.
6.3.6.3. Effect of Minimum Threshold on Beneficial Uses and Users Beneficial uses and users of groundwater storage include maintenance of interconnected surface water and associated groundwater dependent ecosystems (GDEs) and municipal, industrial and other groundwater users. The MTs for groundwater levels are based generally on operational considerations for wells, which recognizes that groundwater has been and is Bedford-Coldwater GSP 6-18
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being used reasonably for the range of beneficial uses even during droughts. The storage minimum threshold is consistent with the water level minimum threshold, which means that available storage will be adequate to supply beneficial uses as long as water levels remain above their minimum thresholds.
6.3.6.4. Relationship of Minimum Threshold to Regulatory Standards Other than SGMA, no federal, state or local standards exist for reduction of groundwater storage.
6.3.6.5. How Management Areas Can Operate without Causing Undesirable Results A storage change in one Management Area would be associated with a change in waterlevels.
That change could affect groundwater flow between that Management Area and an adjoining one. The boundary flow would only change if storage and water levels in the adjoining Management Area did not experience a similar change. Therefore, no incompatibility among Management Areas with respect to storage declines is anticipated.
6.3.6.6. How the Minimum Threshold will be Monitored
Monitoring for the groundwater levels MT, which is the proxy for groundwater storage, will be part of the BCGSA groundwater level monitoring program (as described in Section 7). Data and analytical results, including assessment of change in storage, are presented in GSP Annual Reports.
6.3.7. Measurable Objectives
Measurable Objectives is defined in GSP regulations as an operating range of groundwater storage, allowing changes in groundwater storage with varying hydrologic and surface water supply conditions and as with conjunctive management of surface water and groundwater.
The groundwater level MTs provide a protective level that corresponds to the minimum threshold for storage, which would keep groundwater storage within the historical operating range. The 5-Year GSP Update could include consideration of using more of thisstorage locally as part of ongoing conjunctive use while also protecting shallow wells.
The Measurable Objective for storage is fulfilled by the MO for groundwater levels, which maintains groundwater levels above the historical maximum groundwater depths in each Key Well (as quantified above in Table 6-1).
Groundwater conditions with respect to depletion of groundwater storage are already sustainable. Therefore, no interim milestones are needed to achieve sustainability by 2042.
6.3.7.1. Discussion of Monitoring and Management Measures to be Implemented Management actions to prevent chronic reduction of groundwater storage and to provide groundwater reserves for drought will be the same actions for maintenance of groundwater levels. No otherspecific management actions for storage have been identified and no specific implementation is warranted.
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6.4. SEAWATER INTRUSION
Seawater intrusion does not occur in the Bedford-Coldwater Basin because of its inland location. According to the GSP Regulations, the GSP is not required to establish criteria for such undesirable results that are not likely to occur. Accordingly, the remaining discussion in this section does not address seawater intrusion.
6.5. LAND SUBSIDENCE
Subsidence has not been a known issue in the Bedford-Coldwater Basin and undesirable results have not been reported. Nonetheless, the potential has been recognized that subsidence could occur as a result of groundwater pumping and groundwater level declines, typically in areas underlain by thick layers of fine-grained alluvial sediments.
As described in Section 4.3, available information on vertical land displacement (subsidence) includes estimates from InSAR satellite data systems. InSAR data provide mapping of ground surface elevations across the Basin, presented at regular (typically monthly) intervals.
InSAR data are made available by DWR from the TRE Altamira InSAR Dataset with vertical displacement data beginning in June 2015 and in monthly intervalsthereafter until September 2019. The accuracy of the InSAR ground surface elevation change estimates is reported to be ±16 millimeters (mm), or ±0.052 feet (ft) (Towill 2020). While these data do currently represent a relatively short period of record, the InSAR data do not show significant changes in ground surface elevation in the Basin, which is characterized by small changes within the margin of error. Given the short records of these datasets and small vertical displacements, these data have not been analyzed systematically to identify specific areas that might be subject to long-term subsidence. As datasets are updated, that may be warranted in the future.
There are no data relating potential subsidence to water levels or groundwater pumping in the Basin. SGMA allows groundwater level data to be used as a proxy for subsidence; however,relationships between pumping, groundwater levels, and subsidence have not been determined to support that. Subsidence information from DWR InSAR data will be reviewed as it becomes available.
6.5.1. Description of Undesirable Results
Land subsidence is the differential lowering of the ground surface, which can damage structures, roadways, and hinder surface water drainage. Subsidence remains a potential risk and inelastic subsidence is irreversible. Potential undesirable results associated with land subsidence due to groundwater withdrawals include the following:
• Potential damage to building structures and foundations, including water facilities, due to variations in vertical displacement causing potential cracking, compromised structural integrity, safety concerns and even collapse.
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• Potential differential subsidence affecting the gradient of surface drainage channels, locally reducing the capacity to convey floodwater and causing potential drainage problems and ponding.
• Potential differential subsidence affecting the grade or drainage of other infrastructure such as railroads, roads, and sewers.
• Potential subsidence around a production well, disrupting wellhead facilities or resulting in casing failure.
• Potential non-recoverable loss of groundwater storage as fine-grained layers collapse.
None of these undesirable results has been observed in the Basin. However, subsidence may be subtle and cumulative over time. Accordingly, the potential for future subsidence cannot be ruled out if regional groundwater levels were to decline below historical lows and minimum thresholds.
6.5.2. Potential Causes of Undesirable Results
As described in Section 4.3, changes in ground surface elevations may be caused by regional tectonism or by subsidence related to declines in groundwater elevations due to pumping.
Regarding the former, the InSAR data show a general rising trend in the western portion of the Basin suggesting regional tectonic rise. In contrast, inelastic subsidence associated with groundwater pumping and level declines would generally show a long-term downward trend, with greater subsidence occurring during times of groundwater level decline (e.g., drought) and a flattening trend with no recovery during times of rising groundwater levels and reduced pumping (e.g., wet years).
As groundwater levels decline in the subsurface, dewatering and compaction of predominantly fine-grained deposits (such as clay and silt) can cause the overlying ground surface to settle. Land subsidence due to groundwater withdrawals can be temporary (elastic) or permanent (inelastic). While elastic deformation is relatively minor, fully recoverable, and not an undesirable result, inelastic deformation involves a permanent compaction of clay layers that occurs when groundwater levels in a groundwater basin decline below historical lows. This causes not only subsidence of the ground surface, but also compaction of sediments and loss of storage capacity.
Given the above, the potential for problematic land subsidence is affected by the proportion, overall thickness, and configuration of fine-grained sediments (with greater proportions and thicknesses suggesting greater potential). Because of the variability of local sediments, subsidence also is likely to be geographically variable. Moreover, the potential forsubsidence is affected by the history of groundwater level fluctuations, such that areas with previous groundwater level declines may have already experienced some compaction and subsidence.
Subsidence is possible in Coldwater MA, due to the thickness of sediments and larger amount of pumping in this area. However, there is no evidence of thick, laterally continuous finegrained materials that would be susceptible to subsidence. No data indicate that permanent inelastic subsidence has occurred.
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6.5.3. Potential Effects on Beneficial Uses and Users
The lack of any reports of undesirable results is an indication of no noticeable effects.
Nonetheless, some subsidence could have occurred because of historical groundwater level declines without being noticed and could have contributed to drainage or flooding problems, which are also affected by multiple and sometimes more noticeable factors including variable weather, changes in streams and drainage systems, land use changes in the watershed, erosion and sedimentation. Accordingly, continued tracking of subsidence is warranted.
6.5.4. Minimum Threshold
According to the GSP Regulations Section 354.28(c)(5), the minimum threshold for land subsidence is defined as the rate and extent of subsidence that substantially interferes with surface land uses. This section first addresses the rate at which subsidence substantially interferes with surface land uses and then describes how available InSAR data can be used to measure rate and extent across the Basin.
The Minimum Threshold for subsidence is defined as a cumulative decline equal to or greater than one foot since 2015, which represents current conditions and the SGMA start date. This corresponds to a rate of decline equal to or greater than 0.2 feet in any five-year period.
The one-foot criterion is reasonable based on standards for flooding and drainage and on empirical data for well casing collapse:
• In the southwestern part of the Sacramento Valley, where documented cumulative subsidence has reached several feet, video surveys of 88 undamaged wells and 80 damaged wells showed that casing damage was uncommon in wells where subsidence was less than one foot (LSCE 2014).
• Ground floor elevations are recommended or required to be at least one foot above the Base Flood Elevation in some jurisdictions (see for example FEMA 2011 and City of Temecula 2020). Subsidence above one foot may cause some buildings to become flooded.
• The minimum freeboard along roadside ditches is often required to be one foot above the maximum anticipated water level (see for example San Diego County 2005). Greater subsidence may cause sewer and stormwater flows to flow in unintended directions.
Subsidence impacts can be relatively rapid and noticeable. However, in the Basin any subsidence in the future is likely to be gradually cumulative as would be its undesirable results. Accordingly, the 0.2 ft per 5-year rate of decline is an appropriate criterion, with the understanding that it will be re-evaluated in the 2027 GSP Update.
Based on available data and using the above criterion, significant and unreasonable subsidence has not occurred since 2015 in the Basin. Moreover, it is unlikely that the criterion Bedford-Coldwater GSP 6-22
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will be exceeded in the future as groundwater pumping will be constrained with the MT set for groundwater levels and storage.
The extent of cumulative subsidence across the Basin will be monitored using the InSAR data provided on DWR’s SGMA Data Portal website. The data consist of a closely spaced grid of elevation points approximately 300 feet apart and are characterized by considerable “noise,” meaning that adjacent points often have very different readings at the scale of 1-2 inches.
These data will be smoothed to provide results at a spatial scale at which subsidence would plausibly occur. These values for cumulative elevation change will then be compared annually with the minimum threshold criterion.
6.5.4.1. Relationship of Minimum Threshold to Other Sustainability Indicators Subsidence related to groundwater is closely linked to groundwater levels. It is unlikely that significant inelastic subsidence would occur if groundwater levels remain above historical lows, which have been used to define groundwater level MOs. In addition, the operationally defined MT levels will prohibit significant pumping if water levels decline below historical lows. Accordingly, the minimum threshold for groundwater levels is consistent with and supportive of the objective to prevent subsidence undesirable results.
The subsidence MT would have little or no effect on other MTs. Specifically, subsidence MTs would not result in significant or unreasonable groundwater elevations, would not affect pumping and change in storage, would not affect groundwater quality, orresult in undesirable effects on connected surface water.
6.5.4.2. Effect of Minimum Threshold on Sustainability in Adjacent Areas The Bedford-Coldwater Basin is adjacent to the Temescal Basin and Elsinore Valley Subbasin.
Groundwater flow directions are from the Elsinore Valley Subbasin to the Bedford-Coldwater Basin and from the Bedford-Coldwater Basin to the Temescal Basin with some drainage into the Temescal Wash. The MTs for the Basin represent current conditions; establishment of MTs and maintenance of groundwater levels would not affect the ability of the either the Temescal Basin or Elsinore Valley Subbasin GSAs to achieve or maintain sustainability, as the flows between the basins are relatively minimal, and therefore groundwater levels and, thus, subsidence, in one basin would not affect the other.
6.5.4.3. Effect of Minimum Threshold on Beneficial Uses and Users Subsidence has not been reported in the Basin, but subsidence remains a potential undesirable result that may contribute incrementally to reduced drainage, increased flooding, or other undesirable results. The effects of establishing the numerical subsidence MT are beneficial because they support a greater chance of detecting subsidence, supporting management actions to maintain groundwater levels, and preventing significant subsidence.
6.5.4.4. Relationship of Minimum Threshold to Regulatory Standards There are no federal, state or local standards specifically addressing subsidence. There are standards for flood depth, floodplain encroachment, freeboard in ditches and canals and Bedford-Coldwater GSP 6-23
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slopes of gravity-flow plumbing pipes. These vary somewhat from jurisdiction to jurisdiction, but they are generally similar and were used as the basis for selecting the MT.
6.5.4.5. How Management Areas Can Operate without Causing Undesirable Results The MTs are consistently conceived and applied across both MAs. Tracking and analysis of InSAR mapping over the next five years (until the 5-Year GSP update) may be revealing about the potential for subsidence in the Basin. Meanwhile, maintenance of groundwater levels at or above historical lows consistent with the water level MOs will tend to maintain current conditions between the successive MAs from upstream to downstream.
6.5.4.6. How the Minimum Threshold will be Monitored
The minimum threshold will be monitored using available InSAR areal data to identify any occurrence and areal extent of subsidence. Over the next few years, this evaluation will involve review of temporal InSAR data to discern seasonal elastic fluctuations and potential inelastic declines. In addition, any areal extent will be examined; this may involve smoothing of elevation changes over the InSAR grid to summarize the results to a spatial scale at which subsidence would plausibly occur. The cell values for cumulative elevation change will then be compared with the minimum threshold criterion.
6.5.5. Measurable Objectives
The Sustainability Goal includes the objective to prevent subsidence. Accordingly, the MO is zero subsidence. Undesirable subsidence results have not been reported, and accordingly, no interim milestones are defined.
6.5.5.1. Representative Monitoring
It is assumed that the InSAR subsidence monitoring programs will continue for the foreseeable future and InSAR data will be available from the DWR website. The GSP monitoring program for subsidence will involve annual download of InSAR data with analysis for signs of cumulative inelastic subsidence.
6.5.5.2. Discussion of Management Actions to be Implemented Management actions to prevent subsidence will be coordinated with actions relative to maintenance of groundwater levels. These actions involve maintaining groundwater levels above historical low water levels and will prevent significant inelastic subsidence. No other specific management actions for subsidence have been identified and no specific implementation is warranted.
6.6. DEGRADATION OF WATER QUALITY
Degraded water quality can impair water supply and affect human health and the environment. Impacts to drinking water supply wells can result in increased sampling and monitoring, increased treatment costs, use of bottled water, and loss of wells, which may be taken offline because of quality issues. As described in Groundwater Conditions Sections 4.6 Bedford-Coldwater GSP 6-24
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and 4.7, elevated concentrations in drinking water of some constituents, such as nitrate, can adversely affect human health.
Consideration of the causes and circumstances of water quality conditions is important in Bedford-Coldwater because general mineral quality is naturally poor, especially in the Bedford MA. Nonetheless, groundwater has been used for beneficial purposes including irrigation, municipal, and domestic purposes. Sustainable management is about use and management of groundwater without causing undesirable results but does not necessarily include reversing natural undesirable conditions. According to SGMA (§10727.2(b)(4)), a GSP may—but is not required to—address undesirable results that occurred before and have not been corrected by the SGMA benchmark date of January 1, 2015.
Salt and nitrate loading also are recognized as sources of groundwater quality deterioration.
The sustainability goal to protect groundwater quality is not to reverse undesirable water quality conditions by 2042 but rather to prevent circumstances wherein future management activities might make water quality worse, and insofar as possible to improve water quality in the long run. Implementation of management actions is recognized as needed now and, whether or not the results are perceptible in the short term, such actions will be helpful in the long term.
6.6.1. Potential Causes of Undesirable Results
The quality of groundwaterin Bedford-Coldwater Basin is characterized as mineralized, in part reflecting natural hydrogeologic processes (see Groundwater Conditions Section 4.4).
Groundwater also has been affected by human activities including historical agriculture and current urban, industrial, and other land uses. While contaminant sources of groundwater quality degradation exist, these are effectively regulated as described in Groundwater Conditions Section 4.6 and regularly tracked as part of other monitoring programs.
As described in the Groundwater Conditions section, TDS and nitrate are constituents of concern for the Basin. While there are elevated natural background TDS concentrations in groundwater, TDS also is an indicator of human impacts including infiltration of urban runoff, agricultural return flows, and treated wastewater discharge. Natural nitrate levels in groundwater are generally very low, and elevated concentrations are associated with agricultural activities, septic systems, confined animal facilities, landscape fertilization, and wastewater treatment facility discharges.
Other constituents considered to be contaminants have been documented (see Groundwater Conditions Section 4.6.1 and 4.7) but occurrences of these are either under regulation by the Santa Ana Regional Water Quality Control Board (RWQCB) and State Water Resources Control Board (SWRCB) (e.g., perfluorooctanesulfonic acid [PFOS] and perchlorate) or are naturally occurring with no recent exceedances of MCLs and limited potential for mobilization due to management actions. In addition, mining activities are also regulated through the County Planning Department, the Surface Mining and Reclamation Act, and RWQCB discharge permits.
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6.6.2. Description of Undesirable Results
The processes and criteria relied on to define Undesirable Resultsincluded review of available data and information summarized in the Plan Area and Groundwater Conditions sections and discussions with Bedford-Coldwater stakeholders and local agency representatives.
Undesirable Results are defined in the GSP Regulations (§354.26) as occurring when significant and unreasonable effects for any of the sustainability indicators are caused by groundwater conditions occurring throughout the Basin. The GSA is not responsible for local problems or degradation caused by others. While the Bedford-Coldwater Basin includes regulated facilities with soil and groundwater contamination (see Groundwater Conditions Sections 4.4 and 4.6.1), these sites are under regulatory oversight by State and County agencies; the GSA does not have the mandate or authority to duplicate these programs. This GSP avoids management actions that would spread groundwater contamination through managed aquifer recharge, pumping, or other activities.
6.6.3. Potential Effects on Beneficial Uses and Users
Groundwater is a major source of supply in the Basin and supports a range of beneficial uses including municipal, recreational, industrial, and other uses. Beneficial uses of water and respective water quality objectives are defined by the RWQCB in the Santa Ana River Basin Water Quality Control Plan (Basin Plan).
6.6.4. Sustainable Management Criteria for Groundwater Quality The definition of an Undesirable Result due to degraded water quality—TDS and nitrate concentrations—was evaluated in the context of regulatory objectives in each MA.
The GSA has selected a minimum threshold based on average conditions in monitored supply wells and regulatory limits. The average concentrations are totaled from each well and then divided by the total number of supply wells, to achieve a single value representing average conditions over the entire Basin. While this is slightly different than the suggested methods to determine sustainability, the GSA desired a single quantitative value to guide management.
This is because the issues of concern in Bedford-Coldwater are focused on regional nitrate and salt loading, data are insufficient to define plumes or volumes of water, and the position of isocontours is not applicable.
6.6.4.1. Water Quality Monitoring Program
Currently 12 wells are regularly monitored for TDS and/or nitrate in the Basin by GSA member agencies,shown on Table 6-2. The wells generally are sampled semi-annually with lab analysis for general minerals and physical parameters. Accordingly, this data set can be used to detect a range of problems quickly, to track trends, allow geochemical investigation, and support focused management actions.
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Local Well Name Agency
Corona Well 21 Corona
Corona Well 3 Corona
EVMWD Flagler 2A Well EVMWD
EVMWD Flagler 3A Well EVMWD
EVMWD Station 71 EVMWD
EVMWD Mayhew Well 2 EVMWD
TVWD Well 1A TVWD
TVWD Well 4 TVWD
TVWD TP-1 TVWD
TVWD TP-2 TVWD
TVWD MW 2 - Driving Range TVWD
Glen Ivy Well 1 Glen Ivy
6.6.4.2. Additional Water Quality Programs
In addition to existing monitoring, the BCGSA will conduct the following ongoing water quality coordination activities:
• Periodic review of data submitted to the Department of Pesticide Regulation (DPR), SWRCB Division of Drinking Water (DDW), Department of Toxic Substances Control (EnviroStor), and GeoTracker as part of the Groundwater Ambient Monitoring and Assessment (GAMA) database.
• Continue to participate in Salt and Nutrient Management Plan (SNMP) activities that include the Bedford MA portion of the Basin.
• Coordinate with the RWQCB and Riverside County Division of Environmental Health to discuss constituent trends and concerns in the BCGSA in relation to groundwater pumping.
The purpose of these reviews will be to monitor and summarize the status of constituent concentrations throughout the Basin with respect to typical indicators such as applicable MCLs or secondary MCLs (SMCLs). The GSP Annual Report and 5-Year Update will include a summary of the coordination and associated analyses of conditions. The GSP 5-year updates may include evaluation of whether additional minimum thresholds are needed.
6.6.5. Minimum Thresholds
Minimum Thresholds have been developed for nitrate and TDS using the best available information. MTs for nitrate and TDS are based on current conditions represented by average water quality results from all monitored wells between 2014 and 2019. The average value for each constituent was calculated for each well using results from all samples collected between 2014 and 2019. For wells with one sample, the single value was used; for wells with two or more samples, the average value was used.
Table 6-2. Bedford-Coldwater Water Quality Monitoring Wells Bedford-Coldwater GSP 6-27
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These individual well averages were then averaged together for all wells in each MA and all wells in the Basin, as shown in Table 6-3. The resulting MA and Basin-wide average concentrations provide a simple metric for evaluating TDS and nitrate concentrations in the Basin. For reference, the MCL for nitrate as N is 10 mg/L and the SMCL for TDS is 1,000 mg/L.
Table 6-3. Summary of Recent Average Total Dissolved Solids (TDS) and Nitrate Concentrations by Management Area
Bedford MA Average
Concentration,
2014 - 2019
Coldwater MA Average
Concentration,
2014 - 2019
Basin Wide Average
Concentration,
2014 - 2019
Nitrate as N 3 mg/L 2 mg/L 3 mg/L
TDS 788 mg/L 488 mg/L 713 mg/L
Number of
Wells 9 3 12
According to GSP regulations Section 354.28(c)(4) the minimum threshold shall be based on the number of supply wells, a volume of water, or a location of an isocontour that exceeds concentrations of constituents determined by the GSA to be of concern for the Basin. In setting minimum thresholds for degraded water quality, the GSA shall consider local, state, and federal water quality standards applicable to the basin. For the Bedford-Coldwater Basin, water quality MTs are based on the total number of wells (currently 12) and set for the entire Basin including both MAs.
The TDS water quality Minimum Threshold Basin-wide is defined as 5-year average concentrations not exceeding the 1,000 mg/L Secondary MCL for TDS.
The nitrate water quality Minimum Threshold Basin-wide is defined as 5-year average concentrations not exceeding the 10 mg/L drinking water MCL for Nitrate as Nitrogen.
These MTs are presented with full recognition of data gaps and uncertainties, and with commitment incorporated in this GSP to investigate increasing trends in nitrate and salt loading if they occur, and to coordinate appropriate management actions with regulatory agencies such as the RWQCB.
While the TDS and Nitrate MTs were selected based on the MCL (drinking water standards) to protect the beneficial uses of the Basin, it is recognized that there are other water quality objectives. The Upper Temescal Valley SNMP setsforth anti-degradation goalsforthe Bedford portion of the Basin, and the RWQCB Basin Plan has additional objectives for the Coldwater MA. As noted in Section 4.5.1, the SNMP objectives for the Bedford area are lower than the MCLs. However, the fundamental approach of this GSP is to protect beneficial uses as identified in the Sustainability Goal (Section 6.1). The BCGSA will work with other agencies to help achieve their objectivesfor water quality but will not define sustainability based on those objectives.
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Given historical and ongoing groundwater use, current water quality conditions are considered sustainable. As described in Section 6.6.6, Measurable Objectives, the approach is to implement management actions that will maintain or reduce TDS and nitrate concentrations in the future.
6.6.5.1. Relationship of Minimum Threshold to Other Sustainability Indicators Three of the other sustainability indicators (groundwater level declines, storage depletion, subsidence) are directly linked to groundwater levels, while the sustainability indicator for connected surface water-groundwater dependent ecosystems is related to a rate or volume of surface water depletion, also linked to groundwater levels. The MTs for water quality are not known to be directly related to specific groundwater levels or fluctuationsin groundwater levels. Nonetheless, general relationships are recognized, for example that contaminants may be mobilized by changing groundwater levels or flow patterns. Accordingly, the water quality MTs will help guide potential projects that alter groundwater levels or flow.
6.6.5.2. Effect of Minimum Threshold on Sustainability in Adjacent Areas The Bedford-Coldwater Basin is adjacent to the Elsinore Subbasin and Temescal Basin. Given the likelihood of continued flow between these basins remaining relatively similar current conditions, groundwater flow is likely to remain unchanged and groundwater quality in Bedford-Coldwater is unlikely to affect downstream Temescal Basin.
6.6.5.3. Effect of Minimum Threshold on Beneficial Uses and Users The establishment of the MTs reflects the available data regarding the current condition of the Basin relative to TDS and nitrate concentrations. Establishing the MTs represents no change and recognizes that groundwater has been and is being used reasonably for the range of beneficial uses. The MTs represent a quantified starting point for protection of groundwater quality and for projects and management actions to improve groundwater quality, consistent with a best management practices approach.
6.6.5.4. Relationship of Minimum Threshold to Regulatory Standards The MTs have been established with direct reference to regulatory standards, most notably the State-established MCLs. Other standards exist (including the Basin Plan Objectives set by the RWQCB and the Salt Nutrient Management Plan) that are lower (more strict) than the MTs. However, the Sustainability Goal and MTs are based on drinking water standards in order to protect local beneficial uses of groundwater.
6.6.5.5. How Management Areas Can Operate without Causing Undesirable Results For both MAs, the goal isto protect groundwater quality with reference to beneficial uses and all MTs are based on available information and current conditions. It is not known if the current conditions represent equilibrium conditions between the two MAs or if future changes may occur between them. Future implementation of management actions and projects will be guided by monitoring data and by the consistent goal to protect groundwater quality in both MAs.
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6.6.5.6. How the Minimum Threshold will be Monitored
The GSP is using the best available data from the BCGSA member agencies. The existing monitoring program will be improved and expanded to include dedicated monitoring wells.
These will be included within the regular sampling schedule of the BCGSA and will build on historical records with data on specific constituents and parameters. The data from these dedicated wells will be used to reassess this threshold at the next GSP 5-Year update.
6.6.6. Measurable Objectives
The sustainability goal is to protect groundwater quality with reference to beneficial uses, with general objectives of maintaining groundwater quality, preventing circumstances where future management activities might make water quality worse, and improving groundwater quality in the long term.
6.6.6.1. Description of Measurable Objectives
Measurable Objectives are defined in this GSP using the same metrics and monitoring data as used to define MTs and are established to maintain or improve groundwater quality. Given uncertainties presented by data limitations, a reasonable margin of safety includes the possibility of “negative” monitoring results while positive progress is being made.
The Measurable Objective for TDS is defined as maintaining or reducing 5-year average concentration in the Basin below the TDS Secondary MCL (1,000 mg/L) based on conditions documented in the Annual Reports.
The Measurable Objective for nitrate is defined as maintaining orreducing the 5-year average concentration in the Basin below the nitrate as nitrogen MCL (10 mg/L) based on conditions documented in the Annual Reports.
Measurable Objectives will be evaluated in increments of five years and the numeric values will be presented with comparison to current conditions. This comparison will be discussed in the context of actual progress in implementing measures to improve monitoring and management.
6.6.6.2. Discussion of Monitoring and Management Measures to be Implemented The strategy of this GSP is to identify and implement monitoring and management measures to reduce nitrate and TDS loading. Monitoring and management actions already undertaken are summarized in Plan Area Section 2.1.4. and would be continued. Additional monitoring measures are discussed in following sections.
6.7. DEPLETIONS OF INTERCONNECTED SURFACE WATER
This section builds and extends the discussion in Chapter 4 and the discussion of interconnection of surface water and groundwater. That section provided information on surface water-groundwater connections (both seasonally and with wet years and drought), Bedford-Coldwater GSP 6-30
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identification of potential GDEs, distribution of riparian vegetation, and assessment of animal species that rely on groundwater-supported streamflow.
6.7.1. Description of Undesirable Results
If a stream is hydraulically connected to groundwater, pumping from nearby wells can reduce the amount of stream flow by intercepting groundwater that would have discharged into the stream or by inducing seepage from the stream. Undesirable results associated with stream flow depletion include reduced quality and quantity of aquatic and riparian habitats and reduced water supply to downstream users. Conceptually, adverse habitat impacts can result from decreased rainfall, decreased stream flow and/or lowered groundwater levels. These variables are highly correlated in time: droughts include rainfall reductions, decreased stream flows, and lowered groundwater levels at a time when habitat impacts are usually the most severe. Furthermore, droughts and wet periods are a natural feature of California’s climate and are associated with waxing and waning of habitat conditions.
6.7.2. Potential Causes of Undesirable Results
Depletion of interconnected surface water by groundwater pumping can impact a variety of beneficial uses of surface water. A systematic evaluation of each potential impact is warranted, including impacts on downstream water users, habitats around isolated springs and wetlands, and plants and animalsthat rely on flow orshallow watertable conditions along streams.
6.7.2.1. Surface Water Users
There are no known diverters of surface water from Temescal Wash. Lee Lake Dam and reservoir (just upstream of the Basin) were built in the late 19th century on the site of a small natural lake for the purpose of storing and supplying water to what is now the City of Corona (Ellerbee 1918). The lake no longer serves a water supply function, and in recent years it has been operated solely for recreational fishing under the name “Corona Lake”.
Although not exactly a diversion, EVMWD obtained a permit that is listed as a diversion to reduce its historical discharges of treated effluent from the Regional Wastewater Reclamation Facility (WRF) to Temescal Wash upstream of the Basin, instead discharging most of that water to Lake Elsinore. Up to 3.87 cubic feet per second (cfs) of wastewater discharges that had been going to the Wash have been diverted to Lake Elsinore since 2008, as part of a lake level management plan (Permit 21165 [Application30502]). On January 24, 2020, the SWRCB approved EVMWD’s request for a time extension to generate and divert the full amount of wastewater indicated in the permit. Downstream of the Basin there is no required minimum discharge from Temescal Wash into the Prado Wetlands at the downstream end of the Wash, near Corona. However, there are minimum required discharges of treated wastewater into the wetlands from several wastewater treatment plants in the Corona area north of the Bedford-Coldwater Basin.
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6.7.2.2. Isolated Springs and Wetlands
Small off-channel wetlands are included in the Natural Communities Commonly Associated with Groundwater (NCCAG) on-line vegetation geodatabase (DWR et al. 2020). Almost all areas mapped as wetlands are along Temescal Wash and covered by the evaluation ofriparian vegetation presented in detail below. A handful of polygons totaling 1.4 acres in the BedfordColdwater Basin are located along tributary streams or in low areas west of Temescal Wash.
The vegetation is described as “seasonally flooded”, and the depth to groundwater at those locations is over 100 feet. The mapped vegetation is thus supported by seasonal ponding of rainfall runoff, not groundwater.
6.7.2.3. Animals Dependent on Groundwater
Animals dependent on groundwater include fish that permanently reside in Temescal Wash or migrate up and down the Wash during the high flow season, amphibians, and birds that inhabit riparian vegetation. Temescal Wash historically supported a steelhead trout run, remnants of which persist as resident rainbow trout in Coldwater Canyon Creek (which enters the Bedford-Coldwater Basin from the Santa Ana Mountains). Currently, perennially ponded areas along the lower reaches of the creek support robust population of invasive and exotic predatory species including bass, bullhead, sunfish, carp, and some slider turtles (Russell 2020). Arroyo chub is another fish that was once present in the Santa Ana River watershed, but it has been extirpated in most streams due to these exotic predators. Riverside County Resource Conservation District (RCRCD) implemented the Temescal Creek Native Fish Restoration Project in the early 2000s, which focused on eliminating nonnative plant and animal species that prey upon or create unfavorable habitat conditions for native fish species (Western Riverside County Regional Conservation Authority 2020). However, flow conditions in Temescal Wash do not currently support native fish (Russell 2020).
Animals dependent on riparian vegetation can also be considered dependent on groundwater. The Western Riverside County Multi-Species Habitat Conservation Plan (MSHCP) evaluates the presence and habitat needs of 146 species. The only ones mapped in the vicinity of the Basin are upland plants and burrowing owls, none of which are dependent on groundwater (Western Riverside County Regional Conservation Authority 2020). The federally threatened California coastal gnatcatcheris a bird species associated with sage scrub environments. The designated critical habitat areas are almost exclusively in upland areas outside the Basin. However, edges of a few mapped habitat areas border the Temescal Wash corridor (see Figure 4-20).
The Upper Santa Ana River Habitat Conservation Plan (SARHCP) also covers the Temescal Wash watershed and differsfrom the Western Riverside County MSHCP primarily in providing Endangered Species Act compliance for an additional set of activities related to water infrastructure construction and operation (USARSRA 2020). Although the SARHCP documents habitat suitability and historical observations of several listed species along Temescal Wash, its main focus is on habitat along the mainstem Santa Ana River. Species with fewer than five historical sightings and little suitable habitat include Arroyo chub, southwestern pond turtle, southwestern willow flycatcher, and yellow-breasted chat. There have been more than 25 historical sightings of Least Bells vireo, but no suitable habitat is mapped along Temescal Bedford-Coldwater GSP 6-32
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Wash. The flow regime in Temescal Wash is characterized as ephemeral (correct in many locations) because flow is “heavily diverted for human use” (incorrect) and that local areas of persistent flows result from agricultural return flows (incorrect). No mention is made of wastewater discharges, which are a larger factor in the flow regime. The surface hydrologic model used to support the SARHCP analysis only extends about one mile up the lowermost channelized reach of Temescal Wash. A groundwater model used to support the SARHCP projected declining water levels in the Prado wetlands area, but the plan includes no mitigation measures related to groundwater.
In summary, Temescal Wash does not appear to be a significant habitat for any listed animal species that would potentially be impacted by groundwater pumping or water levels.
However, riparian shrubs and trees and non-listed animal species that use them could potentially be impacted during droughts if lowered groundwater levels cause vegetation dieback or mortality.
6.7.2.4. Riparian Vegetation
The beneficial use of interconnected surface water most likely to be impacted by groundwater pumping is riparian vegetation along Temescal Wash. The Wash traverses three groundwater basins along its 26-mile course from Lake Elsinore to the Prado Wetlands on the Santa Ana River. The entire length of the Wash was evaluated for this GSP to maximize the available information relating vegetation to groundwater and surface flow conditions. The assortment of vegetation types is roughly the same along the entire Wash and includes (in decreasing order of abundance) red willow, California sycamore, Gooddings willow, mulefat and Fremont cottonwood.
The extent and health of riparian vegetation along Temescal Wash was evaluated using three data sets: 1) Google Earth aerial imagery dating back to 1994 (Google Earth 2021), 2) NCCAG mapping of riparian vegetation representing a composite of numerous vegetation mapping efforts around the state (most dating from the early 2000s) (DWR et al. 2020), and 3) TNC’s GDE Pulse on-line mapping tool showing vegetation moisture status based on satellite data (TNC 2020).
Inspection of the aerial imagery revealed substantial mortality of riparian trees at many locations along the entire length of Temescal Wash from 2014 to 2016 and little recovery by 2018 (the most recent image). As an example, the evolution of vegetation along the reach that passes through Dos Lagos Golf Course (near Temescal Canyon Road and Cabot Drive) is illustrated by imagesfrom 1994, 2006, 2014, 2016, and 2018 in Figure 6-2. In 1994, which was just after a prior drought and before urban development, there was moderate coverage of riparian trees in the Temescal Wash channel. Canopy extent and density increased incrementally through 2006 and up to 2014. The 2014 through 2016 drought caused extensive tree mortality evident in the 2016 photo. Only a few trees had recovered by 2018, in spite of wet conditions in 2017.
The health and vigor of riparian vegetation cannot be reliably detected in aerial photographs.
However, spectral analysis of light reflected from the vegetation does provide that Bedford-Coldwater GSP 6-33
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information. Two commonly used metrics of vegetation health and vigor are the normalized difference vegetation index (NDVI) and normalized difference moisture index (NDMI), both of which involve ratios of selected visible and infrared wavelengths. NDVI relates to the greenness of vegetation and NDMI relates to transpiration. These metrics detect sub-lethal vegetation stress not visible in normal aerial imagery. TNC compiled these two metrics from historical satellite imagery for riparian vegetation throughout California and incorporated it into the GDE Pulse on-line mapping tool (TNC 2020). The tool evaluates the metrics for every vegetation polygon in the NCCAG maps. For each polygon, the tool displays time series plots of annualsummertime NDVI and NDMI from 1985 through 2019. GDE Pulse data for NDVI and NDMI confirmed large declines in both of those metrics during 2013 through 2016 in most vegetation polygons along Temescal Wash. Some uncertainty in the methodology is apparent in occasional large differences in trends between adjoining polygons. Declines during 1984 through 1990 were of similar magnitude but not as abrupt in most locations.
A key question is whether vegetation die-back during the recent drought was due to lowered groundwater levels or reduced surface flow. There reportedly was year-round surface flow in the Wash derived from wastewater discharges prior to the drought, and a combination of reduced discharges and drought conditions killed up to 80 percent of the tree canopy in some locations along the Wash (Russell 2020). A careful comparison of the locations and timing of vegetation changes during the 1990 to 2018 period with the location and timing of changes in surface flow, groundwater pumping, and groundwater levels allows some tentative conclusions to be drawn about which factors contribute to vegetation die-back.
6.7.2.4.1. Groundwater Pumping and Shallow Groundwater Levels 1990 through 2018
Pumping from wellsin the Warm Springs and Lee Lake MAsin the Elsinore Valley Subbasin upstream from the Basin and the Bedford MA in the Bedford-Coldwater Basin along Temescal Wash was about three times greater during 1990 through 1993 than during the 2013 to 2016 drought, as shown in Figure 6-3. If water levels were only a function of pumping, they would have been lower in the early 1990s than during the recent drought, but that was not the case (except for 1990). Hydrographs of groundwater levels are available for about 22 wells at about 10 locations along the 15-mile length of Temescal Wash in the Elsinore and Bedford-Coldwater Basins. Many of the wells are in clusters at a single location. At five of the locations, water level records date back to the early 1990s.
Hydrographs of water levels at selected wells near Temescal Wash are shown in Figure 6-
4. Many wells with water-level data are production wells with significant, frequent pumping drawdown. Estimation of static water levels in those wells can be inaccurate in years when the well was operated frequently because it can take days for water levels a pumping to recover to background static levels, and pumping schedules do not always allow that much downtime.
Progressive water level declines during 2012 through 2015 were the largest in the period of record for most wells. However, at the two locations with records dating back to 1990 (Gregory and Barney Lee), water levels were as low or lower in 1990 as in the 2012 to 2015 period. 1990 was the final year of another major drought, which can be seen as the Bedford-Coldwater GSP 6-34
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declining trend in the cumulative departure of rainfall during 1984 through 1990. This suggests that low groundwater levels during 1984 through 1990 might also have caused substantial die-back, after which vegetation slowly recovered.
6.7.2.4.2. Surface Flow 1990 through 2018
Surface flow in Temescal Wash is not strongly correlated with vegetation die-back when the full 1990 through 2018 period is considered. Natural flow in Temescal Wash is mostly ephemeral and sporadic, as indicated by flows at various stream gages in the region (see Figure 4-15). Large natural flow events occur only in response to storm events in winter.
In the absence of a shallow water table, intermittent winter flow events would not be sufficient to sustain riparian vegetation through the dry season.
In contrast, discharges from wastewater reclamation facilities are generally more sustained and have also contributed significant flow to Temescal Wash. Monthly average discharges from four wastewater reclamation facilities along Temescal Wash during 1990 through 2018 are shown in Figure 6-5 and are described below:
• Eastern Municipal Water District (EMWD). By far the largest discharges have been from EMWD near the upper end of Temescal Wash in the Elsinore Subbasin.
EMWD’s service area is located outside the Bedford-Coldwater Basin and beyond the jurisdiction of this and neighboring GSPs. The EMWD discharges since 2005 have typically been around 40 to 50 cfs, which is enough to produce flow down the entire length of Temescal Wash. This is confirmed by gaged flows at the outlet of Lee Lake (7 miles downstream of the discharge), which are also shown in the Figure 6-5. Peak flows at that location coincided with EMWD discharges and were about 20 cfs smaller, reflecting percolation losses between the discharge point and the lake. • Elsinore Valley Municipal Water District (EVMWD) Regional WRF. The Regional WRF is also located near the upstream end of Temescal Wash. Its discharges shifted primarily from the Wash to Lake Elsinore starting around 2008. A small (0.77 cfs) discharge has been required continuously since then, and larger discharges occasionally resume when lake levels are high. The change in discharge operations pre-dated the drought by about 6 years, and vegetation along the 5-mile reach immediately downstream of the discharge location remained relatively healthy throughout the drought. Therefore, the change in EVMWD discharges did not appear to be a significant contributor to vegetation mortality during 2014 through 2016.
• Temescal Valley Water District (TVWD) Lee Lake WRF. The Lee Lake WRF is located about halfway down the Bedford-Coldwater Basin reach of Temescal Wash. Its discharges decreased starting in 2013, which coincided with the start of the drought. The discharges had not been large (about 0.8 cfs) and had already decreased by about half since 2005 due to increased wastewater recycling. • City of Corona WRF-3. This WRF discharges a relatively small (about 0.2 cfs) flow to Temescal Wash upstream of Cajalco Road near the downstream end of the BedfordColdwater Basin. Those discharges would not influence vegetation patterns observed upstream.
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The hiatus in EMWD discharges between January 2013 and February 2017 coincided with the drought and with the observed vegetation mortality. Because groundwater levels also declined to exceptionally low levels during that time, the cause of vegetation die-back cannot be uniquely determined based solely on information for that time period.
Looking farther back in time, riparian vegetation was generally able to increase in extent during the 1990s and early 2000s, when EMWD discharges were rare and generally small. This indicates that the vegetation was not dependent on those flows to become established. By inference, the mortality during 2014 through 2016 was not caused solely by the interruption in the discharges.
6.7.2.5. Riparian Vegetation Summary
The relationship between groundwater pumping, groundwater levels, and vegetation dieback is not clear-cut. If there were a direct correlation between the variables, one would expect to have seen lower groundwater levels and more die-back during the 1990s than during the 2014 to 2016 period, which was not the case. At a more general level, however, riparian vegetation along Temescal Wash was continuously dense and healthy in the Warm Springs portion of the Elsinore Subbasin, where groundwater pumping was very small throughout 1990 to 2018, large wastewater discharges were immediately upstream, and groundwater levels remained consistently shallow. The greatest impacts were along the downstream end of the Bedford Management Area in the Bedford-Coldwater Basin, where groundwater pumping was relatively intense, local wastewater discharges were relatively small, and groundwater levels experienced large declines during 2012 to 2016 (no data for 1990).
6.7.3. Definition of Undesirable Results
The Sustainability Goal includes an objective to support beneficial uses in the Basin, and specifically those related to interconnected surface water. Consistent with that objective, undesirable results of excessive depletion of surface water are:
Riparian vegetation die-back or mortality during droughts of a magnitude that disrupts ecological functions or causessubstantial reductionsin populations of riparian-associated species.
6.7.4. Potential Effects on Beneficial Uses and Users
The analysis presented in this section demonstrates that groundwater conditions are currently sustainable with respect to inter-connected surface water and GDEs. There are no users of surface water in the Basin and there does not appear to be a correlation between groundwater levels and streamflow. Basin outflows appear sufficient to meet the needs of downstream water users. The distribution and health of riparian vegetation does appear to be correlated with groundwater levels, but those levels have recovered since the most recent drought and riparian vegetation is in the process of recovering as well.
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6.7.5. Sustainable Management Criteria for Interconnected Surface Water SGMA requires that the minimum threshold for depletions of interconnected surface water shall be the rate or volume of surface water depletions caused by groundwater use that has adverse impacts on beneficial uses of the surface water and may lead to undesirable results (§354.28(c)(6)). However, GSP Regulations allow GSAs to use groundwater elevation as a proxy metric for any of the sustainability indicators when setting minimum thresholds and measurable objectives (23 California Code of Regulations [CCR] § 354.28(d) and 23 CCR § 354.30(d)).
It would be difficult to define a minimum threshold in terms of flow depletion in this Basin because phreatophytic riparian vegetation appears to be more correlated with areas where depth to water is consistently shallow than with the magnitude or duration of surface flow.
Because there are undoubtedly gains and losses of surface flow along Temescal Wash, and the vegetation impacts are associated with a low watertable when surface flow is not present, it is reasonable to define the minimum threshold in terms of water levels instead of flow.
6.7.6. Minimum Threshold
Given the above, the minimum threshold is defined here by groundwater levels. As noted previously, wells in the groundwater levels monitoring program are production wells with relatively deep screens that have not been sited and designed for tracking surface watergroundwaterinteractions. The lack ofsuch shallow monitoring wellsis a data gap and a source of uncertainty. Hence, the minimum threshold described here is initial. Nonetheless, it is intended to be protective of GDEs until the monitoring program can be refined to better represent near-stream shallow conditions.
Therefore, in the Bedford-Coldwater Basin:
The Minimum Threshold for depletion of interconnected surface water is the amount of depletion that occurs when the depth to water in wells near areas supporting phreatophytic riparian trees is greater than 35 feet for a period exceeding one year.
This threshold corresponds approximately to the depth to water beneath the creek channel near water-level monitoring wells during 2014 through 2016 and is defined for static water levels in the wells listed in Section 6.7.6.5. Given the above uncertainty in the relationships between groundwater pumping, groundwater levels and the health of riparian vegetation, the minimum threshold for interconnected surface water presented here must be considered tentative and subject to revision in future GSP updates. The BCGSA is committed to monitoring vegetation and examining possible management actions to avoid undesirable results. However, given the uncertainty of the relationships between pumping, stream flow, water levels and riparian vegetation health, exceedance of the minimum threshold will first trigger additional study to assess how GSA pumping is affecting shallow water levels.
Undesirable results are considered to commence if water levels along more than half of the total length of reaches in the Basin with dense riparian trees exceed the minimum threshold.
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By this definition, undesirable results did occur in the Bedford-Coldwater Basin during the recent drought, because vegetation die-back occurred along about 3.9 miles of the channel, or about 57 percent of the total length of Temescal Wash in the Basin.
6.7.6.1. Relationship of Minimum Threshold to Other Sustainability Indicators • Groundwater Levels. All the wells used to evaluate the minimum threshold (see Section 6.7.6.5) are also representative wells used for compliance with the minimum threshold for groundwater levels. The groundwater level minimum threshold involves two consecutive quarterly water-level measurements rather than a period of one year. For the wells included in both sets of criteria, the interconnected surface water threshold water levels are generally higher than the water-level thresholds. That is, along the GDE stream reaches, the interconnected surface water criteria restrict water-level declines more than the water-level criteria do. This is the logical result of the different objectives of the two sets of criteria. • Groundwater Storage. The minimum threshold for interconnected surface water would similarly be more restrictive than the minimum threshold for groundwater storage near GDE reaches, because the latter is functionally the same as the minimum threshold for water levels.
• Seawater Intrusion. Seawater intrusion would not occur in the Basin due to its inland location. No minimum threshold was defined and there is no consistency issue.
• Land Subsidence. Significant land subsidence is only likely to occur with groundwater levels below historical minimum levels. The levels specified as minimum thresholds for interconnected surface water are within the historical range and thus unlikely to cause subsidence.
• Water Quality. Water quality issues in the Basin are primarily associated with dispersed loading of nitrate and salinity and long-term increases in ambient concentrations of those constituents. Those processes are generally independent of groundwater levels. Groundwater outflow is an important mechanism for salt removal that requires relatively high groundwater levels on a long-term average basis. High levels and groundwater discharge into streams also benefit riparian vegetation and aquatic habitat. Therefore, the minimum threshold for interconnected surface water is consistent with the minimum threshold for water quality.
6.7.6.2. Effect of Minimum Threshold on Sustainability of Adjacent Areas The areas of interconnected surface water in the Basin are those that are upstream of and adjoining the Temescal Basin. Groundwater and surface water flow is from the BedfordColdwater Basin toward the Temescal Basin, consistent with topography. If water levelsin the Bedford Management Area were lowered, outflow to the Temescal Basin would decrease.
The water levels used to define the minimum threshold for depletion of interconnected surface water are within the historical range of water levels and thus would not cause unreasonable impacts on groundwater availability in the Temescal Basin. By protecting Bedford-Coldwater GSP 6-38
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vegetation along the Temescal Wash—which is a shared waterway between the basins—the minimum threshold will protect those resources for the benefit of both Basins.
6.7.6.3. Effect of Minimum Threshold on Beneficial Uses Surface diversions are not a source of supply in the Basin; all water uses are supported by imported water or groundwater. With respect to groundwater, this GSP does not propose increases in groundwater pumping above existing amounts, so groundwater levels are expected to remain within the historical range. In areas where the minimum-threshold water level for interconnected surface water is higher than the minimum-threshold for chronic lowering of groundwater levels, the interconnected surface water threshold improves groundwater availability.
The minimum threshold is expected to protect beneficial uses of surface water for riparian habitat maintenance.
6.7.6.4. Relationship of Minimum Threshold to Regulatory Standards Other than SGMA, there are no local, state, or federal regulations that specifically address stream flow depletion by groundwater pumping. The California and federal Endangered Species Acts protect species listed as threatened or endangered, including California coastal gnatcatcher. The minimum threshold for depletion of surface water is designed to prevent groundwater conditions from impacting those species beyond the level of impact that has historically occurred.
6.7.6.5. How the Minimum Threshold Will Be Monitored
Eight wells that are currently monitored for water levels are near stream reaches where interconnected surface water has been identified. These wells are listed below and shown on Figure 6-1.
• TVWD TP-1 and TP-2
• TVWD Well 1 (old well)
• TVWD Well 4
• EVMWD Flagler 2A and 3A
• Corona Non-Potable Wells 1 and 2
The wells listed above are all mostly water supply wells with relatively deep screens. They are useful for relating future conditions to historical ones, but they do not provide a reliable indication of the true water table elevation near the ground surface because shallow wells can have different water levels than deep wells.
Shallow monitoring wells are needed in riparian areas to provide accurate water table information and elucidate the relationship between deep water levels and vegetation conditions. One of the management actions in this GSP is to conduct surveys of Temescal Wash to evaluate the feasibility and need for installing shallow monitoring wells. Over time, minimum threshold groundwater elevations can be refined as a result of these surveys.
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6.7.7. Measurable Objective
The measurable objective for interconnected surface water is an amount of depletion that is less than the amount specified as the minimum threshold. Given the uncertainty in the correlation between groundwater levels and vegetation health, no specific rise in shallow groundwater levels or increase in stream flow is identified as providing a preferred set of GDE conditions.