Corona City Council
June 3, 2026

Article 5. Plan Contents for Bedford-Coldwater Basin
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§ 354.20. Management Areas
(a)
Each Agency may define one or more management areas within a basin if the Agency has determined that creation of management areas will facilitate implementation of the Plan.

Management areas may define different minimum thresholds and be operated to different measurable objectives than the basin at large, provided that undesirable results are defined consistently throughout the basin. 114, 135, 509:512

5.4,
Appendix I Figure 5-2
(b) A basin that includes one or more management areas shall describe the following in the Plan:
(1) The reason for the creation of each management area. 114, 509:512

5.4,
Appendix I
(2)
The minimum thresholds and measurable objectives established for each management area, and an explanation of the rationale for selecting those values, if different from the basin at large. 145:183

6.1, 6.2,

6.3, 6.4,

6.5, 6.6, 6.7
(3) The level of monitoring and analysis appropriate for each management area. 189:200 7 (4)
An explanation of how the management area can operate under different minimum thresholds and measurable objectives without causing undesirable results outside the management area, if applicable. 144:183 6
(c)
If a Plan includes one or more management areas, the Plan shall include descriptions, maps, and other information required by this Subarticle sufficient to describe conditions in those areas. 114, 135 5.4 Figure 5-2
Note: Authority cited: Section 10733.2, Water Code.

Reference: Sections 10733.2 and 10733.4, Water Code.

SubArticle 3. Sustainable Management Criteria
§ 354.22. Introduction to Sustainable Management Criteria This Subarticle describes criteria by which an Agency defines conditions in its Plan that constitute sustainable groundwater management for the basin, including the process by which the Agency shall characterize undesirable results, and establish minimum thresholds and measurable objectives for each applicable sustainability indicator.

Note: Authority cited: Section 10733.2, Water Code.

Reference: Section 10733.2, Water Code.

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§ 354.24. Sustainability Goal
Each Agency shall establish in its Plan a sustainability goal for the basin that culminates in the absence of undesirable results within 20 years of the applicable statutory deadline.

The Plan shall include a description of the sustainability goal, including information from the basin setting used to establish the sustainability goal, a discussion of the measures that will be implemented to ensure that the basin will be operated within its sustainable yield, and an explanation of how the sustainability goal is likely to be achieved within 20 years of Plan implementation and is likely to be maintained through the planning and implementation horizon. 145 6.1.1
Note: Authority cited: Section 10733.2, Water Code.

Reference: Sections 10721, 10727, 10727.2, 10733.2, and 10733.8, Water Code. § 354.26. Undesirable Results
(a)
Each Agency shall describe in its Plan the processes and criteria relied upon to define undesirable results applicable to the basin. Undesirable results occur when significant and unreasonable effects for any of the sustainability indicators are caused by groundwater conditions occurring throughout the basin.
145, 148,
156:157,
162:163,
167, 173

6.1.1, 6.2.1,

6.3.1, 6.5.1,

6.6.1, 6.7.1

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(b) The description of undesirable results shall include the following:
(1)
The cause of groundwater conditions occurring throughout the basin that would lead to or has led to undesirable results based on information described in the basin setting, and other data or models as appropriate.
145:146,
149, 157,
163, 168,
173:178

6.1.2, 6.2.2,

6.3.2, 6.5.2,

6.6.2, 6.7.2
(2)
The criteria used to define when and where the effects of the groundwater conditions cause undesirable results for each applicable sustainability indicator. The criteria shall be based on a quantitative description of the combination of minimum threshold exceedances that cause significant and unreasonable effects in the basin. 146:147,
149, 157,
164, 168,
178

6.1.3, 6.2.3,

6.3.3, 6.5.3,

6.6.3, 6.7.3
(3)
Potential effects on the beneficial uses and users of groundwater, on land uses and property interests, and other potential effects that may occur or are occurring from undesirable results.
145:147,
150, 157,
164:166,
178

6.1, 6.2.4,

6.3.4, 6.5.4,

6.6.4, 6.7.4
(c)
The Agency may need to evaluate multiple minimum thresholds to determine whether an undesirable result is occurring in the basin. The determination that undesirable results are occurring may depend upon measurements from multiple monitoring sites, rather than a single monitoring site.
150,
157:159,
166,
169:172,
179

6.2.5, 6.3.5,

6.5.5, 6.6.5,

6.7.5 (d)
An Agency that is able to demonstrate that undesirable results related to one or more sustainability indicators are not present and are not likely to occur in a basin shall not be required to establish criteria for undesirable results related to those sustainability indicators. 162 6.4
Note: Authority cited: Section 10733.2, Water Code.

Reference: Sections 10721, 10723.2, 10727.2, 10733.2, and 10733.8, Water Code.

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§ 354.28. Minimum Thresholds
(a)
Each Agency in its Plan shall establish minimum thresholds that quantify groundwater conditions for each applicable sustainability indicator at each monitoring site or representative monitoring site established pursuant to Section 354.36. The numeric value used to define minimum thresholds shall represent a point in the basin that, if exceeded, may cause undesirable results as described in Section 354.26. 152:156,
159:161,
164:166,
169:172,
179:181

6.2.6, 6.3.6,

6.5.4, 6.6.5,

6.7.6 (b) The description of minimum thresholds shall include the following:
(1)
The information and criteria relied upon to establish and justify the minimum thresholds for each sustainability indicator. The justification for the minimum threshold shall be supported by information provided in the basin setting, and other data or models as appropriate, and qualified by uncertainty in the understanding of the basin setting. 150,
157:159,
166,
169:172,
179

6.2.5,

6.3.5, 6.5.5,

6.6.5, 6.7.5
(2)
The relationship between the minimum thresholds for each sustainability indicator, including an explanation of how the Agency has determined that basin conditions at each minimum threshold will avoid undesirable results for each of the sustainability indicators. 152:156,
159:161,
172,
179:181

6.2.6, 6.3.6,

6.5.6, 6.6.6,

6.7.6 (3) How minimum thresholds have been selected to avoid causing undesirable results in adjacent basins or affecting the ability of adjacent basins to achieve sustainability goals. 152:156,
159:161,
172,
179:181

6.2.6, 6.3.6,

6.5.6, 6.6.6,

6.7.6 (4) How minimum thresholds may affect the interests of beneficial uses and users of groundwater or land uses and property interests.
152:156,
159:161,
172,
179:181

6.2.6, 6.3.6,

6.5.6, 6.6.6,

6.7.6 (5)
How state, federal, or local standards relate to the relevant sustainability indicator. If the minimum threshold differs from other regulatory standards, the Agency shall explain the nature of and basis for the difference.
152:156,
159:161,
172,
179:181

6.2.6, 6.3.6,

6.5.6, 6.6.6,

6.7.6 (6) How each minimum threshold will be quantitatively measured, consistent with the monitoring network requirements described in Subarticle 4. 152:156,
159:161,
172,
179:181

6.2.6, 6.3.6,

6.5.6, 6.6.6,

6.7.6

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(c) Minimum thresholds for each sustainability indicator shall be defined as follows:
(1)
Chronic Lowering of Groundwater Levels. The minimum threshold for chronic lowering of groundwater levels shall be the groundwater elevation indicating a depletion of supply at a given location that may lead to undesirable results. Minimum thresholds for chronic lowering of groundwater levels shall be supported by the following:
(A) The rate of groundwater elevation decline based on historical trends, water year type, and projected water use in the basin.
74:75,
92:95,
147:156,
184 4.1.3, 6.2
Figure 4-3:4-
6, 6-1
(B) Potential effects on other sustainability indicators. 160 6.3.6.1 (2)
Reduction of Groundwater Storage. The minimum threshold for reduction of groundwater storage shall be a total volume of groundwater that can be withdrawn from the basin without causing conditions that may lead to undesirable results. Minimum thresholds for reduction of groundwater storage shall be supported by the sustainable yield of the basin, calculated based on historical trends, water year type, and projected water use in the basin. 156:161 6.3
(3)
Seawater Intrusion. The minimum threshold for seawater intrusion shall be defined by a chloride concentration isocontour for each principal aquifer where seawater intrusion may lead to undesirable results. Minimum thresholds for seawater intrusion shall be supported by the following:
(A) Maps and cross-sections of the chloride concentration isocontour that defines the minimum threshold and measurable objective for each principal aquifer. 162 6.4 (B) A description of how the seawater intrusion minimum threshold considers the effects of current and projected sea levels. 162 6.4
(4)
Degraded Water Quality. The minimum threshold for degraded water quality shall be the degradation of water quality, including the migration of contaminant plumes that impair water supplies or other indicator of water quality as determined by the Agency that may lead to undesirable results. 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 Agency to be of concern for the basin.

In setting minimum thresholds for degraded water quality, the Agency shall consider local, state, and federal water quality standards applicable to the basin. 162:166 6.5

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(5)
Land Subsidence. The minimum threshold for land subsidence shall be the rate and extent of subsidence that substantially interferes with surface land uses and may lead to undesirable results. Minimum thresholds for land subsidence shall be supported by the following:
(A)
Identification of land uses and property interests that have been affected or are likely to be affected by land subsidence in the basin, including an explanation of how the Agency has determined and considered those uses and interests, and the Agency’s rationale for establishing minimum thresholds in light of those effects. 166:172 6.6 (B) Maps and graphs showing the extent and rate of land subsidence in the basin that defines the minimum threshold and measurable objectives. 99, 166:172 6.6 Figure 4-10 (6)
Depletions of Interconnected Surface Water. 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. The minimum threshold established for depletions of interconnected surface water shall be supported by the following:
(A) The location, quantity, and timing of depletions of interconnected surface water. 172:182, 185:188 6.7
Figures 6-
2:6-5
(B)
A description of the groundwater and surface water model used to quantify surface water depletion. If a numerical groundwater and surface water model is not used to quantify surface water depletion, the Plan shall identify and describe an equally effective method, tool, or analytical model to accomplish the requirements of this Paragraph. 179, 185:188 6.7.5
Figures 6-
2:6-5
(d)
An Agency may establish a representative minimum threshold for groundwater elevation to serve as the value for multiple sustainability indicators, where the Agency can demonstrate that the representative value is a reasonable proxy for multiple individual minimum thresholds as supported by adequate evidence. 156:161 6.3 (e)
An Agency that has demonstrated that undesirable results related to one or more sustainability indicators are not present and are not likely to occur in a basin, as described in Section 354.26, shall not be required to establish minimum thresholds related to those sustainability indicators. 162 6.4
Note: Authority cited: Section 10733.2, Water Code.

Reference: Sections 10723.2, 10727.2, 10733, 10733.2, and 10733.8, Water Code.

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§ 354.30. Measurable Objectives
(a)
Each Agency shall establish measurable objectives, including interim milestones in increments of five years, to achieve the sustainability goal for the basin within 20 years of Plan implementation and to continue to sustainably manage the groundwater basin over the planning and implementation horizon.
155:156,
161, 166,
172, 182

6.2.7, 6.3.7,

6.5.5, 6.6.6,

6.7.7 (b)
Measurable objectives shall be established for each sustainability indicator, based on quantitative values using the same metrics and monitoring sites as are used to define the minimum thresholds.
155:156,
161, 166,
172, 182

6.2.7, 6.3.7,

6.5.5, 6.6.6,

6.7.7 (c)
Measurable objectives shall provide a reasonable margin of operational flexibility under adverse conditions which shall take into consideration components such as historical water budgets, seasonal and long-term trends, and periods of drought, and be commensurate with levels of uncertainty.
155:156,
161, 166,
172, 182

6.2.7, 6.3.7,

6.5.5, 6.6.6,

6.7.7 (d)
An Agency may establish a representative measurable objective for groundwater elevation to serve as the value for multiple sustainability indicators where the Agency can demonstrate that the representative value is a reasonable proxy for multiple individual measurable objectives as supported by adequate evidence. 161, 182 6.3.7, 6.7.7 (e)
Each Plan shall describe a reasonable path to achieve the sustainability goal for the basin within 20 years of Plan implementation, including a description of interim milestones for each relevant sustainability indicator, using the same metric as the measurable objective, in increments of five years. The description shall explain how the Plan is likely to maintain sustainable groundwater management over the planning and implementation horizon. 145:147 6.1
(f)
Each Plan may include measurable objectives and interim milestones for additional Plan elements described in Water Code Section 10727.4 where the Agency determines such measures are appropriate for sustainable groundwater management in the basin. 155:156,
161, 166,
172, 182

6.2.7, 6.3.7,

6.5.5, 6.6.6,

6.7.7 (g)
An Agency may establish measurable objectives that exceed the reasonable margin of operational flexibility for the purpose of improving overall conditions in the basin, but failure to achieve those objectives shall not be grounds for a finding of inadequacy of the Plan.
155:156,
161, 166,
172, 182

6.2.7, 6.3.7,

6.5.5, 6.6.6,

6.7.7 Note: Authority cited: Section 10733.2, Water Code.

Reference: Sections 10727.2, 10727.4, and 10733.2, Water Code.

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SubArticle 4. Monitoring Networks
§ 354.32. Introduction to Monitoring Networks
This Subarticle describes the monitoring network that shall be developed for each basin, including monitoring objectives, monitoring protocols, and data reporting requirements.

The monitoring network shall promote the collection of data of sufficient quality, frequency, and distribution to characterize groundwater and related surface water conditions in the basin and evaluate changing conditions that occur through implementation of the Plan.

Note: Authority cited: Section 10733.2, Water Code.

Reference: Section 10733.2, Water Code.
§ 354.34. Monitoring Network
(a)
Each Agency shall develop a monitoring network capable of collecting sufficient data to demonstrate short-term, seasonal, and long-term trends in groundwater and related surface conditions, and yield representative information about groundwater conditions as necessary to evaluate Plan implementation. 189:195 7.1 Table 7-1 (b)
Each Plan shall include a description of the monitoring network objectives for the basin, including an explanation of how the network will be developed and implemented to monitor groundwater and related surface conditions, and the interconnection of surface water and groundwater, with sufficient temporal frequency and spatial density to evaluate the affects and effectiveness of Plan implementation. The monitoring network objectives shall be implemented to accomplish the following:
(1) Demonstrate progress toward achieving measurable objectives described in the Plan. 189:195 7.1 Table 7-1 (2) Monitor impacts to the beneficial uses or users of groundwater. 189:195 7.1 Table 7-1 (3) Monitor changes in groundwater conditions relative to measurable objectives and minimum thresholds. 189:195 7.1 Table 7-1
(4) Quantify annual changes in water budget components. 189:195 7.1 Table 7-1

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(c) Each monitoring network shall be designed to accomplish the following for each sustainability indicator:
(1)
Chronic Lowering of Groundwater Levels. Demonstrate groundwater occurrence, flow directions, and hydraulic gradients between principal aquifers and surface water features by the following methods:
(A)
A sufficient density of monitoring wells to collect representative measurements through depth-discrete perforated intervals to characterize the groundwater table or potentiometric surface for each principal aquifer.
191:192,
199, 203 7.1.1 Figure 7-1 Table 7-2
(B) Static groundwater elevation measurements shall be collected at least two times per year, to represent seasonal low and seasonal high groundwater conditions. 191:192,
199, 203 7.1.1 Figure 7-1 Table 7-2
(2) Reduction of Groundwater Storage. Provide an estimate of the change in annual groundwater in storage. 192:193 7.1.2
(3)
Seawater Intrusion. Monitor seawater intrusion using chloride concentrations, or other measurements convertible to chloride concentrations, so that the current and projected rate and extent of seawater intrusion for each applicable principal aquifer may be calculated. 193 7.1.3
(4)
Degraded Water Quality. Collect sufficient spatial and temporal data from each applicable principal aquifer to determine groundwater quality trends for water quality indicators, as determined by the Agency, to address known water quality issues. 193:194, 199, 203 7.1.5 Figure 7-2 Table 7-2
(5)
Land Subsidence. Identify the rate and extent of land subsidence, which may be measured by extensometers, surveying, remote sensing technology, or other appropriate method. 193 7.1.4

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(6)
Depletions of Interconnected Surface Water. Monitor surface water and groundwater, where interconnected surface water conditions exist, to characterize the spatial and temporal exchanges between surface water and groundwater, and to calibrate and apply the tools and methods necessary to calculate depletions of surface water caused by groundwater extractions. The monitoring network shall be able to characterize the following:
(A) Flow conditions including surface water discharge, surface water head, and baseflow contribution. 194:195 7.1.6
(B) Identifying the approximate date and location where ephemeral or intermittent flowing streams and rivers cease to flow, if applicable. 194:195 7.1.6 (C) Temporal change in conditions due to variations in stream discharge and regional groundwater extraction. 194:195 7.1.6
(D) Other factors that may be necessary to identify adverse impacts on beneficial uses of the surface water. 194:195 7.1.6
(d)
The monitoring network shall be designed to ensure adequate coverage of sustainability indicators. If management areas are established, the quantity and density of monitoring sites in those areas shall be sufficient to evaluate conditions of the basin setting and sustainable management criteria specific to that area. 189:195, 202:203 7.1
Figure 7-1,
7-2
(e) A Plan may utilize site information and monitoring data from existing sources as part of the monitoring network. 189:195 7.1 Table 7-1
(f)
The Agency shall determine the density of monitoring sites and frequency of measurements required to demonstrate short-term, seasonal, and long-term trends based upon the following factors:
(1) Amount of current and projected groundwater use. 189:195 7.1 (2) Aquifer characteristics, including confined or unconfined aquifer conditions, or other physical characteristics that affect groundwater flow. 189:195 7.1 (3)
Impacts to beneficial uses and users of groundwater and land uses and property interests affected by groundwater production, and adjacent basins that could affect the ability of that basin to meet the sustainability goal. 189:195 7.1 (4) Whether the Agency has adequate long-term existing monitoring results or other technical information to demonstrate an understanding of aquifer response. 189:195 7.1

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(g) Each Plan shall describe the following information about the monitoring network:
(1) Scientific rationale for the monitoring site selection process. 189:195 7.1 (2)
Consistency with data and reporting standards described in Section 352.4. If a site is not consistent with those standards, the Plan shall explain the necessity of the site to the monitoring network, and how any variation from the standards will not affect the usefulness of the results obtained. 195:197 7.2
(3)
For each sustainability indicator, the quantitative values for the minimum threshold, measurable objective, and interim milestones that will be measured at each monitoring site or representative monitoring sites established pursuant to Section 354.36. 189:195 7.1 (h)
The 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. 189:195 7.1 (i)
The monitoring protocols developed by each Agency shall include a description of technical standards, data collection methods, and other procedures or protocols pursuant to Water Code Section 10727.2(f) for monitoring sites or other data collection facilities to ensure that the monitoring network utilizes comparable data and methodologies. 195:197 7.2 (j)
An Agency that has demonstrated that undesirable results related to one or more sustainability indicators are not present and are not likely to occur in a basin, as described in Section 354.26, shall not be required to establish a monitoring network related to those sustainability indicators. 189:195 7.1 Note: Authority cited: Section 10733.2, Water Code.

Reference: Sections 10723.2, 10727.2, 10727.4, 10728, 10733, 10733.2, and 10733.8, Water Code
§ 354.36. Representative Monitoring
Each Agency may designate a subset of monitoring sites as representative of conditions in the basin or an area of the basin, as follows:
(a)
Representative monitoring sites may be designated by the Agency as the point at which sustainability indicators are monitored, and for which quantitative values for minimum thresholds, measurable objectives, and interim milestones are defined. 198 7.3

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(b) (b) Groundwater elevations may be used as a proxy for monitoring other sustainability indicators if the Agency demonstrates the following:
(1) Significant correlation exists between groundwater elevations and the sustainability indicators for which groundwater elevation measurements serve as a proxy. 198 7.3 (2)
Measurable objectives established for groundwater elevation shall include a reasonable margin of operational flexibility taking into consideration the basin setting to avoid undesirable results for the sustainability indicators for which groundwater elevation measurements serve as a proxy. 198 7.3
(c) The designation of a representative monitoring site shall be supported by adequate evidence demonstrating that the site reflects general conditions in the area. 198 7.3 Note: Authority cited: Section 10733.2, Water Code.

Reference: Sections 10727.2 and 10733.2, Water Code
§ 354.38. Assessment and Improvement of Monitoring Network (a)
Each Agency shall review the monitoring network and include an evaluation in the Plan and each five-year assessment, including a determination of uncertainty and whether there are data gaps that could affect the ability of the Plan to achieve the sustainability goal for the basin. 200:201 7.5 Table 7-3
(b)
Each Agency shall identify data gaps wherever the basin does not contain a sufficient number of monitoring sites, does not monitor sites at a sufficient frequency, or utilizes monitoring sites that are unreliable, including those that do not satisfy minimum standards of the monitoring network adopted by the Agency. 200:201 7.5 Table 7-3 (c) If the monitoring network contains data gaps, the Plan shall include a description of the following:
(1) The location and reason for data gaps in the monitoring network. 201 Table 7-3 (2) Local issues and circumstances that limit or prevent monitoring. 200:201 7.5 Table 7-3 (d)
Each Agency shall describe steps that will be taken to fill data gaps before the next fiveyear assessment, including the location and purpose of newly added or installed monitoring sites. 200:201 7.5 Table 7-3
(e)
Each Agency shall adjust the monitoring frequency and density of monitoring sites to provide an adequate level of detail about site-specific surface water and groundwater conditions and to assess the effectiveness of management actions under circumstances that include the following:
(1) Minimum threshold exceedances. 189:195 7.1
(2) Highly variable spatial or temporal conditions. 189:195 7.1 (3) Adverse impacts to beneficial uses and users of groundwater. 189:195 7.1 (4) The potential to adversely affect the ability of an adjacent basin to implement its Plan or impede achievement of sustainability goals in an adjacent basin. 189:195 7.1 Note: Authority cited: Section 10733.2, Water Code.

Reference: Sections 10723.2, 10727.2, 10728.2, 10733, 10733.2, and 10733.8, Water Code

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§ 354.40. Reporting Monitoring Data to the Department
Monitoring data shall be stored in the data management system developed pursuant to Section 352.6. A copy of the monitoring data shall be included in the Annual Report and submitted electronically on forms provided by the Department.

Note: Authority cited: Section 10733.2, Water Code.

Reference: Sections 10728, 10728.2, 10733.2, and 10733.8, Water Code.

SubArticle 5. Projects and Management Actions
§ 354.42. Introduction to Projects and Management Actions This Subarticle describes the criteria for projects and management actions to be included in a Plan to meet the sustainability goal for the basin in a manner that can be maintained over the planning and implementation horizon.

Note: Authority cited: Section 10733.2, Water Code.

Reference: Section 10733.2, Water Code.
§ 354.44. Projects and Management Actions
(a)
Each Plan shall include a description of the projects and management actions the Agency has determined will achieve the sustainability goal for the basin, including projects and management actions to respond to changing conditions in the basin. 204:218 8 (b) Each Plan shall include a description of the projects and management actions that include the following:
(1)
A list of projects and management actions proposed in the Plan with a description of the measurable objective that is expected to benefit from the project or management action.

The list shall include projects and management actions that may be utilized to meet interim milestones, the exceedance of minimum thresholds, or where undesirable results have occurred or are imminent. The Plan shall include the following:
(A)
A description of the circumstances under which projects or management actions shall be implemented, the criteria that would trigger implementation and termination of projects or management actions, and the process by which the Agency shall determine that conditions requiring the implementation of particular projects or management actions have occurred. 204:218

8.1,8.2,8.3,

8.4,8.5,8.6,

8.7,8.8
Tables 8-
1:8-8
(B)
The process by which the Agency shall provide notice to the public and other agencies that the implementation of projects or management actions is being considered or has been implemented, including a description of the actions to be taken. 204:218

8.1,8.2,8.3,

8.4,8.5,8.6,

8.7,8.8
Tables 8-
1:8-8
(2)
If overdraft conditions are identified through the analysis required by Section 354.18, the Plan shall describe projects or management actions, including a quantification of demand reduction or other methods, for the mitigation of overdraft. Not applicable (3) A summary of the permitting and regulatory process required for each project and management action. 204:218

8.1,8.2,8.3,

8.4,8.5,8.6,

8.7,8.8
Tables 8-
1:8-8

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(4) The status of each project and management action, including a time-table for expected initiation and completion, and the accrual of expected benefits. 204:218

8.1,8.2,8.3,

8.4,8.5,8.6,

8.7,8.8
Tables 8-
1:8-8
(5) An explanation of the benefits that are expected to be realized from the project or management action, and how those benefits will be evaluated. 204:218

8.1,8.2,8.3,

8.4,8.5,8.6,

8.7,8.8
Tables 8-
1:8-8
(6)
An explanation of 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. 204:218

8.1,8.2,8.3,

8.4,8.5,8.6,

8.7,8.8
Tables 8-
1:8-8
(7) A description of the legal authority required for each project and management action, and the basis for that authority within the Agency. 204:218

8.1,8.2,8.3,

8.4,8.5,8.6,

8.7,8.8
Tables 8-
1:8-8
(8) A description of the estimated cost for each project and management action and a description of how the Agency plans to meet those costs. 204:218

8.1,8.2,8.3,

8.4,8.5,8.6,

8.7,8.8
Tables 8-
1:8-8
(9)
A description of the management of groundwater extractions and recharge to ensure that chronic lowering of groundwater levels or depletion of supply during periods of drought is offset by increases in groundwater levels or storage during other periods. 204:218

8.1,8.2,8.3,

8.4,8.5,8.6,

8.7,8.8
Tables 8-
1:8-8
(c) Projects and management actions shall be supported by best available information and best available science. 204:218

8.1,8.2,8.3,

8.4,8.5,8.6,

8.7,8.8
Tables 8-
1:8-8
(d) An Agency shall take into account the level of uncertainty associated with the basin setting when developing projects or management actions. 204:218

8.1,8.2,8.3,

8.4,8.5,8.6,

8.7,8.8
Tables 8-
1:8-8
Note: Authority cited: Section 10733.2, Water Code.

Reference: Sections 10727.2, 10727.4, and 10733.2, Water Code.

Bedford-Coldwater GSP

TODD GROUNDWATER,
H&H Water Resources,
and Stantec

APPENDIX D
BCGSA Stakeholder Outreach Plan

STAKEHOLDER OUTREACH PLAN
BEDFORD COLDWATER GROUNDWATER SUBBASIN (#8-004.02)
of the ELSINORE BASIN (#8-004)

RIVERSIDE COUNTY, CALIFORNIA

SUSTAINABLE GROUNDWATER MANAGEMENT ACT
(SGMA) PROGRAM
Prepared For:

BEDFORD COLDWATER

GROUNDWATER SUSTAINABILITY AUTHORITY
Acting as a Groundwater Sustainability Agency
Prepared By:

Stantec Consulting Services, Inc.
300 North Lake Avenue, Suite 400
Pasadena, CA 91101
October 2018
Updated October 2021

TABLE OF CONTENTS
LIST OF ACRONYMS AND ABBREVIATIONS……………………………………………………... i

1.0 INTRODUCTION................................................................................................................1

2.0 OBJECTIVES ....................................................................................................................1

3.0 STAKEHOLDER IDENTIFICATION ..................................................................................1

4.0 OUTREACH ACTIVITIES..................................................................................................3

4.1 Public Notices and Meetings ....................................................................................3

4.1.1 Public Meetings ............................................................................................4

4.1.2 Agency Meetings ..........................................................................................4

4.2 GSA Website............................................................................................................4

4.3 Direct Mailings/Email................................................................................................5

4.4 Outreach Implementation Timeline ..........................................................................5

5.0 EVALUATION....................................................................................................................7

5.1 Public Meeting Participation and Attendance...........................................................7

5.2 Comment and Response Database .........................................................................7

6.0 REFERENCES...................................................................................................................7

APPENDIX A - SUMMARY OF STATUTORY REQUIREMENTS

i

LIST OF ACRONYMS AND ABBREVIATIONS
BCGSA Bedford Coldwater Groundwater Sustainability Authority acting as a Groundwater Sustainability Agency
CASGEM California Statewide Groundwater Elevation Monitoring Corona City of Corona
DAC disadvantaged community
DWR California Department of Water Resources
EVMWD Elsinore Valley Municipal Water District
GSA Groundwater Sustainability Agency
GSP Groundwater Sustainability Plan
JPA Joint Powers Authority
SGMA Sustainable Groundwater Management Act
TVWD Temescal Valley Water District

OUTREACH PLAN
_____________________________________________________________________________________________________________________ 1 1.0 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 Authority (BCGSA) was formed as a result of a Joint Powers Agreement to create a Joint Powers Authority (JPA). The JPA consists of the City of Corona (Corona), Elsinore Valley Municipal Water District (EVMWD), and Temescal Valley Water District (TVWD) acting as the Groundwater Sustainability Agency (GSA) for the Bedford Coldwater Groundwater Subbasin (Subbasin), a subbasin of the Elsinore Groundwater Basin. The BCGSA will be responsible for creating a Groundwater Sustainability Plan (GSP) to achieve long-term groundwater sustainability in the Subbasin.

Under SGMA Regulations (California Water Code [Water Code] Section 10723.2), the BCGSA must consider all beneficial users and users of groundwater throughout the GSP development process. The BCGSA, comprised of three local agencies, will strive to achieve sustainable groundwater management in the region in the best interests of the stakeholders and local community.

This Stakeholder Outreach Plan (Outreach Plan) outlines the communication methods and strategies the BCGSA will employ to most effectively engage and involve stakeholders throughout GSP development and SGMA implementation per California Water Code.

2.0 OBJECTIVES
The purpose of this Outreach Plan is to involve stakeholders and understand their values throughout development of the GSP for the Subbasin. The objectives of the Outreach Plan are to:
• Identify and include interested stakeholders, including: affected governments, agencies, land use and environmental organizations, interested parties, and members of the public • Provide multiple forums for stakeholder involvement
• Encourage stakeholder input throughout the GSP development process • Receive and understand information about stakeholders’ values and interests • Incorporate comments and feedback received during GSP development • Abide by SGMA Regulations and ensure broad public participation and transparency

3.0 STAKEHOLDER IDENTIFICATION
SGMA Regulations require GSAs to consider the interests of all beneficial users and users of groundwater (Water Code Section 10723.2), and establish and maintain a list of persons interesting in receiving notices regarding plan preparation, meeting announcements, and availability of draft plans, maps, and other relevant documents (Water Code Section 10723.4). Per Water Code Section 10723.8(a)(4), a list of interested parties was developed and provided to DWR during formation of the BCGSA. The BCGSA will continue to expand this list throughout the GSP development process. An initial list of stakeholders is presented in Table 1.

OUTREACH PLAN
_____________________________________________________________________________________________________________________ 2 Table 1 – List of Stakeholders in the BCGSA Area
Category Identified Stakeholders
Holders of overlying groundwater rights –
Agricultural users None identified
Holders of overlying groundwater rights –
Domestic well owners
• Golf Club at Glen Ivy
• Shea Homes, Inc.
• Other small producers
Municipal well operators
• City of Corona Department of Water and Power
• Elsinore Valley Municipal Water District
• Temescal Valley Water District
Industrial well operators • Coldwater Aggregates
Public water systems
• Western Municipal Water District
• Eastern Municipal Water District
• City of Corona Department of Water and Power
• Elsinore Valley Municipal Water District
• Temescal Valley Water District
Local land use planning agencies • Riverside County, Planning Department • City of Corona
Regulatory Agencies
• Riverside County Flood Control and Water
Conservation District
• California Regional Water Quality Control Board –
Santa Ana Region (8)
Environmental Groups • The Nature Conservatory
Surface water users, if there is a
hydrologic connection between surface
and groundwater bodies
• Santa Ana Watershed Protection Agency
• City of Corona Department of Water and Power
• Elsinore Valley Municipal Water District
• Temescal Valley Water District
The Federal Government • United States Forest Service
• United States Fish and Wildlife Service
California State Agencies
• California Department of Water Resources
• California Department of Fish and Wildlife
Groundwater Program
California Native American Tribes
• Soboba Band of Luiseño Indians
• Rincon Band of Luiseño Indians
• Agua Caliente Band of Cahuilla Indians
• Temecula Band of Luiseño Indians
Disadvantaged communities (DAC),
including, but not limited to, those served
by private domestic wells or small
community water systems
None identified
Entities listed in Water Code Section
10927 that are monitoring and reporting
groundwater elevations in all or a part of a
groundwater basin managed by the
groundwater sustainability agency
Elsinore Valley Municipal Water District is the entity
responsible for the California Statewide Groundwater
Elevation Monitoring (CASGEM) program

OUTREACH PLAN
_____________________________________________________________________________________________________________________ 3 3.1 Tribal Lands in the Basin
There are no tribal entities with land within the Basin. The list of stakeholders includes four California Native American tribes in the region, though not with land in the Basin, in order to continue the long history of coordination with tribal entities between the GSA agencies. The tribes have been contacted for stakeholder meetings as well as for consultation during the California Environmental Quality Act (CEQA) process for two new monitoring wells. The tribes have indicated no specific interest in the Basin, however the BCGSA will continue to consult with the tribes throughout GSP implementation and CEQA permitting.

3.2 Private Well Owners
The BCGSA believes there are very few active private wells, none of which are used for potable water supply in the Basin. While the BCGSA is aware of a small number of private wells, a systematic well inventory identifying all active private wells has not been completed to date. The GSP 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.

4.0 OUTREACH ACTIVITIES
The BCGSA will implement the following outreach activities to maximize stakeholder involvement during development and implementation of the GSP. A summary of SGMA stakeholder outreach requirements and Water Code sections (Dobbin, 2015) are included in Table A.1 of Appendix A.

4.1 Public Notices and Meetings
SGMA establishes public notice requirements for GSAs to ensure that the general public and other stakeholders, are aware of actions by their local GSA. Table 2 outlines the three sections of the Water Code that require public notice, including before establishing a GSA, before adopting or amending a GSP, and before imposing or increasing a fee.

Table 2 – SGMA Requirements for Public Notice
Public Notice Requirement Water Code
Section
“Before deciding to become a groundwater sustainability agency, and after publication of notice pursuant to Section 6066 of the Government Code, the local agency or agencies shall hold a public hearing in the county or counties overlying the basin.”
10723(b)
“A groundwater sustainability agency may adopt or amend a groundwater sustainability plan after a public hearing, held at least 90 days after providing notice to a city or county within the area of the proposed plan or amendment.” 10728.4
“Prior to imposing or increasing a fee, a groundwater sustainability agency shall hold at least one public meeting, at which oral or written presentations may be made as part of the meeting.”
10730(b)(1)

OUTREACH PLAN
_____________________________________________________________________________________________________________________ 4 The BCGSA will satisfy these requirements by publishing notices in local news outlets for Riverside County (The Press-Enterprise) and the City of Corona (Sentinel Weekly News), as well as posting on the BCGSA website.

In accordance with Water Code Section 10723(b), the following notices were provided to the public during formation of the BCGSA:
• On March 15, 2017 and March 22, 2017, a notice of public hearing was published in The PressEnterprise and Sentinel Weekly News to inform the public of the intent to hold a public hearing to consider the proposed decision by Bedford-Coldwater Groundwater Sustainability Authority to become the GSA for the Bedford-Coldwater Subbasin of the Elsinore Basin. • On March 29, 2017, the Bedford-Coldwater Groundwater Sustainability Authority held a public hearing in the Boardroom of the Temescal Valley Water District’s headquarters to hear comments from the public regarding the Bedford-Coldwater Groundwater Sustainability Authority’s proposal to form a GSA within the Bedford-Coldwater Subbasin.

4.1.1 Public Meetings
To promote broad public participation and stakeholder involvement (Water Code Section 10727.8(a)), the BCGSA will conduct at least two public meetings during development of the GSP. Each meeting will be open to stakeholders and will include agency representatives. These meetings will be an opportunity for stakeholders to ask questions and provide input on sections of the GSP.

Public meetings will be held in the Boardroom of the Temescal Valley Water District’s headquarters, located at 22646 Temescal Canyon Road, Temescal Valley, California 92883. More information including date and time of upcoming meetings will be provided on the BCGSA website. Throughout stakeholder outreach, the BCGSA will evaluate if additional accommodations will be necessary (e.g., evening meetings, translation for hearing impaired or non-English speaking individuals, etc.) in order to include as many stakeholders as possible.

As of this 2021 update, two public meetings have been held: November 7, 2019 in the Temescal Valley Water District boardroom, and July 15, 2021 online via Zoom. Since the start of the COVID-19 pandemic, to encourage participation and ensure the safety of all participants, all public and JPA Board meetings have been conducted through online formats.

Stakeholders will continue to be encouraged to participate in meetings and engage with BCGSA members following adoption of the GSP through email updates and website postings. Public meetings will be held as needed prior to significant updates made to the GSP throughout GSP implementation. Meeting information will be made available on the BCGSA website.

4.1.2 JPA Board Meetings
Representatives of each agency comprising the BCGSA will be present during quarterly Board meetings with the JPA. The dates, times, and location of these meetings will be posted on the BCGSA website. Time is designated during these meetings for the BCGSA to provide the JPA with updates on the progress of GSP development and SGMA implementation. There will be opportunity for the public to pose questions and comments at the start of each meeting. This public comment period will continue throughout GSP implementation.

4.2 GSA Website
The BCGSA will develop a website to facilitate the sharing of information about GSP development and SGMA implementation with stakeholders. Information will include maps, a calendar of upcoming meetings

OUTREACH PLAN
_____________________________________________________________________________________________________________________ 5 and important dates, meeting summaries, groundwater information, relevant documents, mailing list signup, and other SGMA/GSA related information. The BCGSA website is located at:
www.bedfordcoldwatergsa.com
The website will be updated regularly. There will be a designated page where users are encouraged to request more information, ask questions, or be added to the list of stakeholders. Links to the BCGSA website will be provided on the homepages of member agency websites.

Prior to initiating the development of a GSP, SGMA Regulations require that GSAs make a written statement describing the manner in which interested parties may participate in the development and implementation of the GSP available to the public and to DWR (Water Code Section 10727.8(a)). A section of the BCGSA website will allow the public to access this statement, the Outreach Plan, and any other written requirements.

4.3 Direct Mailings/Email
The BCGSA will maintain and continue to update a list of stakeholders. The list will be updated as persons request information though the website and from attendance at public meetings. Information distributed to those on the list who are interested in receiving BCGSA updates may include, plan preparation, meeting announcements, and availability of draft plans, maps, and other relevant documents (Water Code Section 10723.4).

4.4 Outreach Implementation Timeline
Stakeholder engagement opportunities will be tracked and available on the BCGSA website throughout the GSP development process. Figure 1 shows the required stakeholder engagement opportunities throughout the four phases of GSP development as described by DWR (DWR, 2018). Forms of stakeholder engagement may include public meetings, information distributed to the BCGSA list of stakeholders, or DWR open public comment periods online via the SGMA Portal found at https://sgma.water.ca.gov/portal/#intro.

Phase 1 (years 2015 to 2017) is the GSA Formation and Coordination phase and includes one stakeholder input requirement. This requirement was completed by holding a public hearing to form the GSA from the Bedford Coldwater Groundwater Sustainability Authority.

Phase 2 (year 2017 to 2022) is the GSP Preparation and Submission part of the GSP development process.

During this phase, stakeholders will be provided with opportunities to provide input on sections of the GSP by attending public meetings or reaching out on the BCGSA website.

Phase 3, occurring at any point after completion of Phase 2, consists of GSP review and evaluation. Once the GSP is submitted, any person may provide comments to DWR regarding a proposed or adopted GSP via the SGMA Portal found on DWR’s website.

Phase 4 (year 2022+) is the Implementation and Reporting phase following adoption of the GSP. Active stakeholder involvement and public meetings are encouraged by DWR during this phase.

OUTREACH PLAN
__________________________________________________________________________________________________________________________________________________________________ 6 Figure 1 – Stakeholder Input Timeline (adapted from DWR, 2018)

OUTREACH PLAN
_____________________________________________________________________________________________________________________ 7 5.0 EVALUATION
GSAs are encouraged to continually evaluate the effectiveness and monitor the progress of stakeholder engagement. The BCGSA will monitor the effectiveness of the Outreach Plan throughout GSP development and implementation by actively revising and updating the Outreach Plan to reflect any changing needs of stakeholders. The stakeholders list will be updated as needed to ensure all interested groups and beneficial users are included.

5.1 Public Meeting Participation and Attendance
Recording attendance and participation at public meetings is one method the BCGSA will use to implement the Outreach Plan and identify any adjustments that may be required. A record of attendance will be taken at each public meeting, and written feedback request forms will be available to each attendee. The forms will allow a clear pathway for the BCGSA to receive direct feedback on how to improve engagements with the public, if necessary, and to ensure individual interests are documented and considered.

5.2 Comment and Response Database
The BCGSA will maintain a database in order to ensure that comments voiced during public meetings and throughout stakeholder engagement are addressed. The database will track comments (and other information including name, date, and venue), assign responsibility for response preparation, and track distribution of responses. A copy of the information contained in the database will be included in the GSP as required by GSP Regulations Section 354.10.

6.0 REFERENCES
California Department of Water Resources (DWR), 2018. “Guidance Document for Groundwater Sustainability Plan, Stakeholder Communication and Engagement.” Sustainable Groundwater Management Program. January.

Dobbin, Kristin, et al., 2015. “Collaborating for Success: Stakeholder Engagement for Sustainable Groundwater Management Act Implementation.” Community Water Center. July.

Water Code Sections can be found online at California Legislative Information. <https://leginfo.legislature.ca.gov/faces/home.xhtml>

APPENDIX A
Summary of Statutory Requirements

Table A.1 – Summary of Statutory Requirements for Stakeholder Engagement in SGMA Timeframe Requirement
California
Water Code
Section
During GSA
Formation
“Before electing to be a groundwater sustainability
agency… the local agency or agencies shall hold
a public hearing”
10723 (b)
“A list of interested parties [shall be] developed
[along with] an explanation of how their interests
will be considered”
10723.8(a)(4)
During GSP
Development and
Implementation
“A groundwater sustainability agency may adopt
or amend a groundwater sustainability plan after a
public hearing”
10728.4
“Prior to imposing or increasing a fee, a
groundwater sustainability agency shall hold at
least one public meeting”
10730(b)(1)
“The groundwater sustainability agency shall
establish and maintain a list of persons interested
in receiving notices regarding plan preparation,
meeting announcements, and availability of draft
plans, maps, and other relevant documents”
10723.4
“Any federally recognized Indian Tribe… may
voluntarily agree to participate in the preparation
or administration of a groundwater sustainability
plan or groundwater management plan… A
participating Tribe shall be eligible to participate
fully in planning, financing, and management
under this part”
10720.3(c)
“Prior to initiating the development of a
groundwater sustainability plan, the groundwater
sustainability agency shall make available to the
public and the department a written statement
describing the manner in which interested parties
may participate in the development and
implementation of the groundwater sustainability
plan”
10727.8(a)
Throughout SGMA
Implementation
“The groundwater sustainability agency shall
consider the interests of all beneficial uses and
users of groundwater”
10723.2
“The groundwater sustainability agency shall
encourage the active involvement of diverse
social, cultural, and economic elements of the
population within the groundwater basin”
10727.8(a)

Bedford-Coldwater GSP

TODD GROUNDWATER,
H&H Water Resources,
and Stantec

APPENDIX E
Public Meeting Summaries

www.bedfordcoldwatergsa.com
31315 Chaney Street, Lake Elsinore, CA 92530
Board Members:

Paul Rodriguez, TVWD
Jacque Casillas, City of Corona
Phil Williams, EVMWD

MEETING SUMMARY
Public Meeting
Bedford Coldwater Groundwater Sustainability Authority
6:30 PM, November 7, 2019
22646 Temescal Valley Road, Temescal Valley, CA 92883
Attendees
Craig Kessler, SoCal Golf Association
Kevin Fitzgerald, SoCal Golf Association
Rachel Gray, Eastern Municipal Water District
Kristian Aifelor, City of Corona Department of Water and Power Sonny Gowan, ECS/Glen Ivy
Arean Park, KOK/Tom’s Farms
Mike Buckantz, Associates Environmental
Jim St. Martin, Chandler’s Sand and Gravel
Trevor Wood, Chandler’s Sand and Gravel
Pakiza Chatha, California Department of Water Resources Ray Alvarez, Glen Ivy Hot Springs
Brandon Barnett, KWC Engineers
Charley Land, California Department of Fish and Wildlife Ian Achimore, Santa Ana Watershed Project Authority
Jacque Casillas, City of Corona
Phil Williams, Elsinore Valley Municipal Water District Margie Armstrong, Elsinore Valley Municipal Water District Tom Moody, City of Corona
Jeff Pape, Temescal Valley Water District
Victor Harris, Stantec
Kelly Shugart, Stantec
Agenda

1. Welcome and Introductions

2. Introduction to the Sustainable Groundwater Management Act (SGMA)

3. Bedford Coldwater Groundwater Sustainability Authority

4. Open Discussion

5. Next Steps
Victor Harris presented on the above topics followed by an open discussion. Comments from stakeholders were mostly addressed by Victor Harris, Tom Moody, and Jeff Pape are summarized below.

General comments from Jeff Pape, TVWD:
• It will be helpful for the BCGSA to know details about stakeholders’ wells in the Subbasin: Has anyone had to lower pumps? Any water quality issues? • We are interested in obtaining the earliest well data available for warm water and cold water wells.

2 General comments from Tom Moody, City of Corona
• The BCGSA is interested in gaining information about the geology where wells have been drilled in order to better understand the hydrogeology and the water entering those wells.
• We want to understand where recharge is occurring in the Subbasin and that we have recharge occurring in the correct location for future modelling efforts. • We are interested in the native safe yield at each of the wells in the Subbasin so the BCGSA can know how much can be pumped safely without damaging the aquifer.

Stakeholder Comment: Will future development go into recharge in the Subbasin? Response: The BCGSA will need to do a water study, but yes, it’s possible.

Stakeholder Comment: Does water withdrawn in the basin stay in the basin or is it transported out?
Response: Most of the water stays in or very near the basin, but not 100% of it. Any exports out of the Subbasin is another aspect we need to understand. TVWD imports 100% of its potable water, about 3,000 acre-feet.

Stakeholder Comment: Is any of the water used for recharge? Response: Recycled water is percolated into the ground.

Stakeholder Comment: What should we worry about for future projects? Response: We will try to plan for known development as part of the Master Plan, for example, recycled water is required for landscape irrigation. If something deviates from the Master Plan, we will need to work it out with the developer.

Stakeholder Comment: For future projects, will developments need to be equipped with a reservoir or way to capture rainwater?
Response: It’s possible; we want to minimize runoff and maybe look into xeriscaping. Future developments could be required to do stormwater management.

Knowing how much runoff we are saving could go into offsetting extractions.

Stakeholder Comment: There is a creek passing through my client’s land and they are experiencing erosion. Would it be possible to use [BCGSA] budget to create a reservoir to hold water on that land?
Response: If it promotes general sustainability, it could be a possibility.

Stakeholder Comment: Will you develop regulations for new and existing developments? Response: There could be guidance setup for minimizing runoff, for example. The BCGSA will continue to review and update the GSP regularly. As regulations change, we will need to see how our plan fits and update, as needed.

Stakeholder Comment: Can you speak more to fees?
Response: Extraction fees are a possible authority, but it is more about compliance.

It would be an enforcement amount. Fees could potentially used as funding for new projects or enforcement.

Stakeholder Comment: Is the GSA’s authority a one-size fits all or will you look at each user individually concerning compliance with policies? Not everything would fit for the spa, for example, like landscaping policies.

Response: Policies will need to be practical and equitable for everyone.

3 Stakeholder Comment: How do you plan on gathering data? Response: We will be asking users for any data they have. Lots of wells are de minimus, less than 2 acre-feet per year, or hard rock wells and are exempt. We are in contact with most of the larger producers and hope to have good relationships with everyone in the basin. We really want to know the geology and to understand the basin.

Stakeholder Comment: Are you reaching out to other stakeholders? Response: We have contacted all we are aware of in the basin. Do you have suggestions on how to reach others? We will be reaching out during a data gathering period and will publish our list of stakeholders. We will be careful of confidentiality, especially with the mining operations. We need to understand the basin without hurting business. We will be asking everyone for their information.

DWR Comment: How can stakeholders stay engaged?
Response: Attend meetings which are posted on the BCGSA website. A listserv is a good way to keep people engaged and send notifications automatically. We will also add the presentation slides to the website.

11/1/2021
1 Bedford Coldwater Subbasin
Groundwater Sustainability Plan
Public Meeting – Thursday, November 7, 2019
Presenter: Victor Harris, PG, CEG, CHG
Agenda

1. Welcome and Introductions

2. Introduction to the Sustainable
Groundwater Management Act (SGMA)

3. Bedford Coldwater Groundwater
Sustainability Authority

4. Open Discussion

5. Next Steps
Meeting Objectives
 Help keep you informed about the
Sustainable Groundwater Management Act
 Understand your needs and priorities
 Open lines of communication
 Build common goals for the Bedford
Coldwater Subbasin
Introduction to the Sustainable
Groundwater Management Act
1 2
3 4

11/1/2021
2 The Sustainable Groundwater
Management Act (SGMA)  Sustainable Groundwater Management Act (SGMA) was passed by the California legislature in 2014  Created a framework for sustainable groundwater management in California  Sustainable Groundwater Management = “Management and use of groundwater in a manner that can be maintained during the
planning and implementation horizon without
causing undesirable results.”
“…groundwater management in California is best accomplished locally.” – Governor Jerry Brown, September 2014
SGMA  Requires the formation of Groundwater Sustainability Agencies (GSAs) – generally agencies overlying the groundwater basin  GSAs are responsible for preparing Groundwater Sustainability Plans (GSPs) and be submitted by:  January 2020 for critically over drafted basins  January 2022 for remaining high and medium priority basins  Creates a single sustainability goal for the basin or subbasin  Achieved within 20 years of GSP implementation  Maintained without causing undesirable results SGMA
Two main goals to promote basin health:

1. Stop overdraft by “balancing the
water budget”

2. Achieve sustainable yield and avoid
six undesirable results Lowering GW Levels Reduction of Storage Seawater Intrusion Degraded Quality Land Subsidence Surface Water Depletion Joseph, Trevor, April 2018. DWR’s Sustainable Groundwater Management Program Assistance Webinar. GSP Development presentation slides. 5 6
7 8

11/1/2021
3 Basin Prioritization  Four groundwater basin categories:

High, medium, low, and very low  Based on components in California Water Code Section 10933(b)  Population overlying basin or subbasin  Number of wells that draw from the basin  Irrigated acreage overlying the basin  Reliance on groundwater for primary source of water Groundwater Sustainability
Agencies  Allows for intervention by the State
Water Resources Control Board (SWRCB)
at points throughout the process of
achieving sustainable groundwater
management  SGMA Required Groundwater Sustainability Agencies (GSAs) be formed  Expanded the role of DWR to support local implementation of sustainable groundwater management by GSAs Powers and Authority of a GSA  Adopt rules, regulations, ordinances and resolutions to achieve groundwater sustainability  Conduct investigations for the purpose of:  Determining the need for groundwater management  Preparing and adopting a GSP and implementing rules and regulations  Proposing and updating fees  Monitor compliance and enforcement  Inspection of property or facilities to ascertain compliance  Require registration of a groundwater extraction facility  Require measurement and recording of groundwater extraction (costs borne by owner or operator)  Require groundwater extraction facilities to file an annual report
Powers and Authority of a
GSA (continued)  Acquire land, water rights, rights-of-way, structures, or other property  Appropriate and acquire surface or groundwater (or rights thereof)  Transport, reclaim, purify, desalinate or treat wastewater or polluted water  Additional authorities  Regulate or limit groundwater extractions  Limit construction of new wells, or reactivation of older wells  Authorize transfers and carryover of groundwater extraction allocations 9 10
11 12

11/1/2021
4 Groundwater Sustainability Plan  GSP development must be a transparent and open process encouraging stakeholder and
public input  Establish minimum thresholds for each
sustainability indicator to avoid undesirable
results
Bedford Coldwater Groundwater
Sustainability Authority
Bedford Coldwater Groundwater
Sustainability Authority  Joint Powers Authority (JPA) formed by three local agencies in February 2017 for management of the Subbasin  City of Corona  Elsinore Valley Municipal Water District  Temescal Valley Water District City of Corona TVWD Jacque Casillas, Director Phil Williams, Vice-Chairman EVMWD Paul Rodriguez, Chairman  JPA signed a resolution in March 2017 to become the GSA for the Subbasin  Governed by a representative Board member from each agency
Bedford Coldwater GSA
Basin and Agency Boundaries
13 14
15 16

11/1/2021
5 Bedford Coldwater Subbasin
Prioritization  Bedford Coldwater
Subbasin classified as a
very low priority
subbasin  Groundwater use
<9,500 acre-feet per
year and no
documented impacts to
the subbasin DWR SGMA Basin Prioritization Tool
2017 Prop 1 SGWP Grant  BCGSA was awarded funding by the Department of Water Resources (DWR) of the State of California
through the Proposition 1 Sustainable Groundwater
Planning (SGWP) Grant  SGWP Grant provides funding to assist in financing the planning and/or selected project activities
that will improve sustainable groundwater
management  BCGSA submits quarterly progress reports to DWR under the conditions of the grant
GSP Development
The First Step is a Conceptual Model
GSP Development
A Water Budget is Key to the
Conceptual Model
17 18
19 20

11/1/2021
6 Geologic
Map of the
Bedford
Coldwater
Subbasin
GSP Development
From Conceptual Model to
Groundwater Flow Model
Conceptual Model Water Budget Numerical Groundwater Model Potential Projects for BCGSA  Drill new, or locate suitable existing wells for groundwater monitoring  Surface water instrumentation and monitoring  Baseline groundwater
quality sampling
GSP Development Timeline
July 2019
• Begin Draft GSP development
July 2020
• Draft GSP available for public review
December 2020
• Final Draft GSP submitted to DWR
21 22
23 24

11/1/2021
7 Open Discussion  Who are the private groundwater users in the Subbasin?  Rough estimate of volume used  Use of groundwater  Groundwater quality  Concerns?  Who has concerns about the current groundwater conditions or elements of the GSP?  What specific subject matter should be discussed in the GSP?
Next Steps  How can you stay involved?  Visit our website: www.BedfordColdwaterGSA.com  Attend BCGSA Board meetings  Provide current contact information for BCGSA updates  Contact Victor Harris at 626-840-3592, [email protected]  Please complete our survey before you leave Thank you for your interest and participation in
the Bedford Coldwater Subbasin!
25 26

www.bedfordcoldwatergsa.com
31315 Chaney Street, Lake Elsinore, CA 92530
Board Members:

Paul Rodriguez, TVWD
Jacque Casillas, City of Corona
Phil Williams, EVMWD

MEETING SUMMARY
Public Meeting to Review the Bedford Coldwater Basin Draft Groundwater Sustainability Plan (GSP)
Bedford Coldwater Groundwater Sustainability Authority
6:00 PM, July 15, 2021
Online Zoom Meeting
Attendees
Rachel Gray, Eastern Municipal Water District
Kristian Alfelor, City of Corona Department of Water and Power Sonny Gowan, ECS/Glen Ivy
Jim St. Martin, Chandler’s Sand and Gravel
Mike Weil, California Department of Water Resources
Brent Miles, Glen Ivy Hot Springs
Phil Williams, Elsinore Valley Municipal Water District Margie Armstrong, Elsinore Valley Municipal Water District Ganesh Krishnamurthy, Elsinore Valley Municipal Water District Parag Kalaria, Elsinore Valley Municipal Water District Paul Rodriguez, Temescal Valley Water District
Melissa Estrada-Maravilla, City of Corona
Jesus Gastelum, Elsinore Valley Municipal Water District Sodavy Ou, West Yost Associates
Jerry Sincich, Temescal Valley Municipal Advisory Council (MAC) Craig Deleo, Temescal Driving Range
Eric Werner, Werner Corporation
Tom Moody, City of Corona
Jeff Pape, Temescal Valley Water District
Chad Taylor, Todd Groundwater
Maureen Reilly, Todd Groundwater
Terese Quintanar, Elsinore Valley Municipal Water District Victor Harris, H & H Water Resources
Kelly Shugart, Stantec
Agenda

1. Groundwater Sustainability Plan (GSP) Background

2. Introduction to the Bedford Coldwater Basin

3. SGMA Requirements

4. Recommended Actions and Projects

5. Schedule and Timeline

6. Questions, Comments, and Open Discussion
The second Stakeholders Meeting of the Bedford-Coldwater Groundwater Sustainability Authority was held via teleconference. Participants joined by accessing Zoom web meeting.

The meeting began at 6:00 p.m. and was recorded.

2 Mr. Victor Harris made introductions of those attending and explained methods for participants to indicate the desire to speak or ask questions. Mr. Harris explained that the purpose of the meeting was to present a summary of the recently completed Bedford Coldwater Groundwater Sustainability Plan (GSP), and invite questions or comments from basin stakeholders. He presented and explained a PowerPoint presentation and welcomed questions and comments at the completion of the presentation. The PowerPoint is attached to this summary for reference.

After the PowerPoint presentation, the following questions were posed by stakeholders:

Stakeholder Question: Are there any new regulations that would prohibit private well owners from replacing or installing new wells?
Response: The BCGSA and GSP has not introduced new regulations regarding well installations and will adopt the Riverside County well guidance. Well regulations can be found on the Riverside County website.

Stakeholder Question: Are you willing to discuss the GSP with local citizens groups in the Temescal Valley?
Response: Yes.

Because of the relatively few questions or concerns voiced by attendees, Mr. Harris invited additional comments or questions during the public review period (ending September 6, 2021) via email or telephone contact (contact information was provided in the presentation). He also requested responses to a questionnaire distributed immediately after the meeting via email to invitees.

The meeting ended at approximately 7:00 pm.

Bedford Coldwater Subbasin
Groundwater Sustainability Plan
Public Meeting – Thursday, July 15, 2021
Presenter: Victor Harris, PG, CEG, CHG
BCGSA Administrator

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Meeting Information

Agenda

1. Groundwater Sustainability Plan (GSP)
Background

2. Introduction to the Bedford Coldwater Basin

3. SGMA Requirements

4. Recommended Actions and Projects

5. Schedule and Timeline

6. Questions, Comments, and Open Discussion

Acknowledgements
 Bedford-Coldwater Groundwater
Sustainability Authority (BCGSA)
Board and Staff
 California Department of Water
Resources (DWR) Funding
Jacque Casillas,
Director
Phil Williams,
Vice-Chairman
Paul Rodriguez,
Chairman

First Stakeholder Meeting
Questions and Input
 November 7, 2019, Temescal Valley Water District
 Introduction to Sustainable Groundwater Management Act (SGMA), BGSA, and GSP development
Issues Discussed:
 Protection of water
quality
 Future projects
 New regulations
 Fees
 How to stay engaged

SGMA Background
 Sustainable Groundwater Management Act (SGMA)
was passed by the California legislature in 2014
 Stop overdraft and achieve sustainable yield
 Requires the formation of Groundwater
Sustainability Agencies (GSAs) overlying the
groundwater basin
 GSAs are responsible for preparing Groundwater
Sustainability Plans (GSPs)
“…groundwater management in California is
best accomplished locally.”
– Governor Jerry Brown, September 2014

BedfordColdwater
Subbasin
• Coldwater Management
Area
• Bedford Management
Area

Geology of the Basin

Groundwater Level History

SGMA Terminology
 Sustainability Criteria = Quantitative ways
the GSA can define, measure, and track
sustainable management
 Undesirable results = 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
 Management Action = Initiated when MTs
are approached or exceeded
Lowering
GW Levels
Reduction
of Storage
Seawater
Intrusion
Degraded
Quality
Land
Subsidence
Surface Water
Depletion

Joseph, Trevor, April 2018. DWR’s Sustainable Groundwater Management Program Assistance Webinar. GSP Development presentation slides.

Six Undesirable Results

Consequences of Undesirable
Results
 Increased pumping costs
 Entrained air in discharge/accelerated
corrosion
 Loss of production
 Loss of groundwater-dependent habitat
 Subsidence
 Loss of groundwater in storage
 Loss of emergency supply

Sustainability Goal for the
Bedford-Coldwater Basin
 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.

Minimum Thresholds for
Sustainability
Sustainability Criteria Minimum Threshold
Lowering of GW Levels Maintain water levels at or above current pump intakes or screens (2 exceedances occur in 2 consecutive years in >2/3 or more wells in each management area)
Reduction of GW in Storage Based on water levels
Land Subsidence 0.2 feet in any 5-year period
Degradation of GW Quality 5-year average TDS<1,000 mg/l, Nitrates<10 mg/l Depletion of
Interconnected Streams
Depth to water in wells near groundwater-supported
vegetation is more than 35 ft for more than 1 year
Well Screen
Water Table
Pump

Monitoring Network
Flaggler 2A
Corona 3
New Sump

Monitoring Well
Construction and
Transducer Installation

Management Action 1
 Provide for Collection, Compilation, and Storage
of Information Required for Annual Reports and
Submit Annual Reports
Contents
 Executive Summary
 Groundwater Contour Maps
 Hydrographs
 Extraction Amounts
 Amount of Imported Supply
 Change in Groundwater in Storage
 Progress in Plan Implementation

Management Action 2
 Routinely Record Groundwater Levels and Take
Action if Necessary

Management Action 3
 Monitor Selected Groundwater Quality
Constituents and Coordinate with the Regional
Water Quality Control Board

Management Action 4
 Track Trends in Groundwater Levels Near Temescal
Wash and Take Action as Necessary

Management Action 5
 Review InSAR* Data on the DWR Dataviewer During
5-Year Updates
* Interferometric Synthetic Aperture Radar

Project 1
 Investigate
Groundwater/
Surface Water
Interaction at
Temescal Wash

Project 2
 Initiate a Survey of Active Private Wells

Project 3
 Evaluation of Interaction of Aggregate Pits and
Groundwater Flow

Benefits of the GSP
 Ensures long-term sustainability of the Basin
 Evaluates and prepares for climate change
 Protects groundwater-dependent ecosystems
 Protects all groundwater users in the Basin
 Provides for transparent and open Basin management
 Provides for continuing stakeholder input

GSP Implementation Schedule
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Select GSP Administrator 
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 Action 4 – Track Trends in Groundwater Levels near Temescal Wash and Take Action as Necessary
Action 5 – Review InSAR data on the SGMA Dataviewer During Annual and 5-year Updates     
Project 1 – Investigate Groundwater/Surface Water Interaction at Temescal Wash
Project 2 – Initiate a Survey of Private Wells
Project 3 – Evaluation of the Effects of Aggregate Pits on Groundwater Flow and Quality
Prepare 5-Year Evaluation 
2022 2023 2024 2025 2026

Survey
Meeting Date: July 15, 2021
Organization or Business Name: ______________________________________________________________ Stakeholder Name: __________________________________________________________________________ Email:__________________________________________________________ Phone: ____________________________________________ How helpful was this meeting in understanding development of the draft GSP for the Bedford-Coldwater Subbasin? Please circle response: 1 2 3 4 5
Not helpful Neutral Very helpful
Please provide suggestions for improvement of stakeholder outreach:

Question: Response:

3. Is the timeline for GSP implementation clear?

4. Do you have any concerns or suggestions about implementing the GSP in the BedfordColdwater Subbasin?

5. Please note any other comments or questions regarding implementation of the GSP in the Bedford-Coldwater Subbasin or the GSP document itself. (Reminder: written comments are due on the Draft GSP by September 6, 2021. Please email this survey and any addtional comments to [email protected]).

2. Do you own or operate a water well in the vicinity of the basin? Do you plan to in the future?

1. Has this presentation increased your knowledge about the Groundwater Sustainability Plan (GSP)?
Please submit your survey to
[email protected]

Open Discussion
 How can you stay involved?
 Visit our website: www.BedfordColdwaterGSA.com
 Attend BCGSA Board meetings
 Provide current contact information for BCGSA
updates
 Contact Victor Harris at 626-840-3592 or:
[email protected]
Thank you for your interest and participation in
the Bedford Coldwater Subbasin GSP!

11/1/2021
1 Bedford Coldwater Subbasin
Groundwater Sustainability Plan
Public Meeting – Thursday, July 15, 2021
Presenter: Victor Harris, PG, CEG, CHG
BCGSA Administrator
Agenda

1. Groundwater Sustainability Plan (GSP)
Background

2. Introduction to the Bedford Coldwater Basin

3. SGMA Requirements

4. Recommended Actions and Projects

5. Schedule and Timeline

6. Questions, Comments, and Open Discussion
Acknowledgements
 Bedford-Coldwater Groundwater
Sustainability Authority (BCGSA)
Board and Staff
 California Department of Water
Resources (DWR) Funding
Jacque Casillas, Director Phil Williams, Vice-Chairman Paul Rodriguez, Chairman First Stakeholder Meeting
Questions and Input  November 7, 2019, Temescal Valley Water District  Introduction to Sustainable Groundwater Management Act (SGMA), BGSA, and GSP development
Issues Discussed:  Protection of water quality  Future projects  New regulations  Fees  How to stay engaged 1 2
3 4

11/1/2021
2 SGMA Background  Sustainable Groundwater Management Act (SGMA) was passed by the California legislature in 2014  Stop overdraft and achieve sustainable yield  Requires the formation of Groundwater Sustainability Agencies (GSAs) overlying the
groundwater basin  GSAs are responsible for preparing Groundwater Sustainability Plans (GSPs) “…groundwater management in California is best accomplished locally.” – Governor Jerry Brown, September 2014
BedfordColdwater
Subbasin
• Coldwater Management Area
• Bedford Management Area
Geology of the Basin
5 6
7 8

11/1/2021
3 Groundwater Level History
SGMA Terminology
 Sustainability Criteria = Quantitative ways
the GSA can define, measure, and track
sustainable management
 Undesirable results = 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
 Management Action = Initiated when MTs
are approached or exceeded
Lowering GW Levels Reduction of Storage Seawater
Intrusion Degraded Quality Land Subsidence Surface Water Depletion Joseph, Trevor, April 2018. DWR’s Sustainable Groundwater Management Program Assistance Webinar. GSP Development presentation slides.

Six Undesirable Results
9 10
11 12

11/1/2021
4 Consequences of Undesirable
Results
 Increased pumping costs
 Entrained air in discharge/accelerated
corrosion
 Loss of production
 Loss of groundwater-dependent habitat
 Subsidence
 Loss of groundwater in storage
 Loss of emergency supply
Sustainability Goal for the
Bedford-Coldwater Basin  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.

Minimum Thresholds for
Sustainability
Sustainability Criteria Minimum Threshold
Lowering of GW Levels Maintain water levels at or above current pump intakes or screens (2 exceedances occur in 2 consecutive years in >2/3 or more wells in each management area)
Reduction of GW in Storage Based on water levels Land Subsidence 0.2 feet in any 5-year period Degradation of GW Quality 5-year average TDS<1,000 mg/l, Nitrates<10 mg/l Depletion of
Interconnected Streams Depth to water in wells near groundwater-supported vegetation is more than 35 ft for more than 1 year Well Screen Water Table Pump Monitoring Network Flaggler 2A Corona 3 New Sump
13 14
15 16

11/1/2021
5 Monitoring Well
Construction and
Transducer Installation
Management Action 1  Provide for Collection, Compilation, and Storage of Information Required for Annual Reports and
Submit Annual Reports Contents  Executive Summary  Groundwater Contour Maps  Hydrographs  Extraction Amounts  Amount of Imported Supply  Change in Groundwater in Storage  Progress in Plan Implementation Management Action 2  Routinely Record Groundwater Levels and Take Action if Necessary
Management Action 3  Monitor Selected Groundwater Quality Constituents and Coordinate with the Regional
Water Quality Control Board
17 18
19 20

11/1/2021
6 Management Action 4  Track Trends in Groundwater Levels Near Temescal Wash and Take Action as Necessary
Management Action 5  Review InSAR* Data on the DWR Dataviewer During 5-Year Updates * Interferometric Synthetic Aperture Radar Project 1  Investigate
Groundwater/
Surface Water
Interaction at
Temescal Wash
Project 2  Initiate a Survey of Active Private Wells
21 22
23 24

11/1/2021
7 Project 3  Evaluation of Interaction of Aggregate Pits and Groundwater Flow
Benefits of the GSP  Ensures long-term sustainability of the Basin  Evaluates and prepares for climate change  Protects groundwater-dependent ecosystems  Protects all groundwater users in the Basin  Provides for transparent and open Basin management  Provides for continuing stakeholder input GSP Implementation Schedule Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Select GSP Administrator P Action 1 – Provide for Collection, Compilation, and Storage of Information Required For Annual Reports and Submit Annual Reports P P P P P 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 Action 4 – Track Trends in Groundwater Levels near Temescal Wash and Take Action as Necessary Action 5 – Review InSAR data on the SGMA Dataviewer During Annual and 5-year Updates P P P P P Project 1 – Investigate Groundwater/Surface Water Interaction at Temescal Wash Project 2 – Initiate a Survey of Private Wells Project 3 – Evaluation of the Effects of Aggregate Pits on Groundwater Flow and Quality Prepare 5-Year Evaluation P 2022 2023 2024 2025 2026 Open Discussion  How can you stay involved?  Visit our website: www.BedfordColdwaterGSA.com  Attend BCGSA Board meetings  Provide current contact information for BCGSA updates  Contact Victor Harris at 626-840-3592,or:
[email protected]
Thank you for your interest and participation in
the Bedford Coldwater Subbasin GSP!
25 26
27 28

Meeting Date: July 15, 2021
Organization or Business Name: ______________________________________________________________Stakeholder Name:
__________________________________________________________________________ Email:__________________________________________________________ Phone: ____________________________________________How helpful was this meeting in understanding development of the draft GSP for the Bedford‐Coldwater Subbasin?Please circle response: 1 2 3 45 Not helpful Neutral Very helpful
BCGSA Stakeholder Survey
Question: Response:3. Is the timeline for GSP implementation clear?4. Do you have any concerns or suggestions about implementing the GSP in theBedford‐Coldwater Subbasin?5. Please note any other comments or questions regarding implementation of the GSP in the Bedford‐Coldwater Subbasin or the GSP document itself. ( Reminder: written comments are due on the Draft GSP by September 6, 2021.Please email this survey and any addtional comments [email protected] ).2. Do you own or operate a water well in the vicinity of the basin? Do you plan toin the future?1. Has this presentation increased your knowledge about the Groundwater Sustainability Plan (GSP)?
Please provide suggestions for improvement of stakeholder outreach:

Bedford-Coldwater GSP

TODD GROUNDWATER,
H&H Water Resources,
and Stantec

APPENDIX F
Draft GSP Comments and Responses

September 6, 2021
Bedford Coldwater Groundwater Sustainability Authority
c/o Temescal Valley Water District
22646 Temescal Valley Road
Temescal Valley, CA 92883
Submitted via email: [email protected]
Re: Public Comment Letter for the Bedford-Coldwater Basin Draft GSP Dear Victor Harris,
On behalf of the above-listed organizations, we appreciate the opportunity to comment on the Draft Groundwater Sustainability Plan (GSP) for the Bedford-Coldwater Basin being prepared under the Sustainable Groundwater Management Act (SGMA). Our organizations are deeply engaged in and committed to the successful implementation of SGMA because we understand that groundwater is critical for the resilience of California’s water portfolio, particularly in light of changing climate. Under the requirements of SGMA, Groundwater Sustainability Agencies (GSAs) must consider the interests of all beneficial uses and users of groundwater, such as domestic well owners, environmental users, surface water users, federal government, California Native American tribes and disadvantaged communities (Water Code 10723.2).

As stakeholder representatives for beneficial users of groundwater, our GSP review focuses on how well disadvantaged communities, tribes, climate change, and the environment were addressed in the GSP.

While we appreciate that some basins have consulted us directly via focus groups, workshops, and working groups, we are providing public comment letters to all GSAs as a means to engage in the development of GSPs across the state. Recognizing that GSPs are complicated and resource intensive to develop, the intention of this letter is to provide constructive stakeholder feedback that can improve the GSP prior to submission to the State.

Based on our review, we have significant concerns regarding the treatment of key beneficial users in the Draft GSP and consider the GSP to be insufficient under SGMA. We highlight the following findings:

1. Beneficial uses and users are not sufficiently considered in GSP development. a. Human Right to Water considerations are not sufficiently incorporated. b. Public trust resources are not sufficiently considered. c. Impacts of Minimum Thresholds, Measurable Objectives and Undesirable Results on beneficial uses and users are not sufficiently analyzed.

2. Climate change is not sufficiently considered.

3. Data gaps are not sufficiently identified and the GSP does not have a plan to eliminate them.

Bedford-Coldwater Basin Draft GSP Page 1 of 11

4. Projects and Management Actions do not sufficiently consider potential impacts or benefits to beneficial uses and users.

Our specific comments related to the deficiencies of the Draft Bedford-Coldwater Basin GSP along with recommendations on how to reconcile them, are provided in detail in Attachment A.

Please refer to the enclosed list of attachments for additional technical recommendations:

Attachment A GSP Specific Comments
Attachment B SGMA Tools to address DAC, drinking water, and environmental beneficial uses and users
Attachment C Freshwater species located in the basin
Attachment D The Nature Conservancy’s “Identifying GDEs under SGMA: Best Practices for using the NC Dataset”
Thank you for fully considering our comments as you finalize your GSP.

Best Regards,
Ngodoo Atume
Water Policy Analyst
Clean Water Action/Clean Water Fund
Samantha Arthur
Working Lands Program Director
Audubon California
E.J. Remson
Senior Project Director, California Water Program
The Nature Conservancy
J. Pablo Ortiz-Partida, Ph.D.

Western States Climate and Water Scientist
Union of Concerned Scientists
Danielle V. Dolan
Water Program Director
Local Government Commission
Melissa M. Rohde
Groundwater Scientist
The Nature Conservancy
Bedford-Coldwater Basin Draft GSP Page 2 of 11

Attachment A
Specific Comments on the Bedford-Coldwater Basin Draft Groundwater Sustainability Plan

1. Consideration of Beneficial Uses and Users in GSP development Consideration of beneficial uses and users in GSP development is contingent upon adequate identification and engagement of the appropriate stakeholders. The (A) identification, (B) engagement, and (C) consideration of disadvantaged communities, drinking water users, tribes, groundwater dependent ecosystems, streams, wetlands, and freshwater species are essential for ensuring the GSP integrates existing state policies on the Human Right to Water and the Public Trust Doctrine.

A. Identification of Key Beneficial Uses and Users
Disadvantaged Communities, Drinking Water Users, and Tribes The identification of Disadvantaged Communities (DACs), drinking water users, and tribes is insufficient , due to lack of clarity around tribal lands in the basin. The GSP states that there are no tribal lands in the basin, but includes four tribes in the list of stakeholders presented in Appendix D, Table 1.

The GSP indicates that there are no DACs in the basin (Section 2.1.2). The GSP includes a map of the density of domestic wells in the basin (Figure 2-4). The GSP should be further improved by including a map of individual domestic well locations and by indicating the population dependent on groundwater for their source of drinking water.

The missing elements regarding tribes and domestic wells are required for the GSA to fully understand the specific interests and water demands of these beneficial users, to support the development of water budgets using the best available information, and to support the development of sustainable management criteria and projects and management actions that are protective of these users.

RECOMMENDATIONS
● Describe the occurrence of tribal lands in the basin. If tribes have interests in the basin, describe them in detail.
● Include a map of individual domestic well locations and a table of well data showing screen depths. Indicate the population dependent on groundwater for their source of drinking water.

Interconnected Surface Waters
The identification of Interconnected Surface Water (ISW) is insufficient .

The GSP describes the use of aerial photos to analyze stream reaches during the dry season.

However, this analysis is insufficient to determine interconnected reaches. The GSP states: “the reach of Temescal Wash that passes through the Bedford-Coldwater Basin does not appear to Bedford-Coldwater Basin Draft GSP Page 3 of 11

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.” Both of these sentences appear to discount the time periods when the stream reaches may be interconnected. The regulations [23 CCR §351(o)] define ISW as “surface water that is hydraulically connected at any point by a continuous saturated zone to the underlying aquifer and the overlying surface water is not completely depleted”. “At any point” has both a spatial and temporal component. Even short durations of interconnections of groundwater and surface water can be crucial for surface water flow and supporting environmental users of groundwater and surface water.

Therefore, potential ISWs are not being identified, described, nor managed in the GSP. Until a disconnection can be proven, include all potential ISWs in the GSP. This is necessary to assess whether surface water depletions caused by groundwater use are having an adverse impact on environmental beneficial users of surface water.

RECOMMENDATIONS
● Provide a map showing all the stream reaches in the basin, with reaches clearly labeled. Consider any segments with data gaps as potential ISWs and clearly mark them as such on maps provided in the GSP.
● Provide depth-to-groundwater contour maps using the best practices presented in Attachment D, to aid in the determination of ISWs. Specifically, ensure that the first step is contouring groundwater elevations, and then subtracting this layer from land surface elevations from a digital elevation model (DEM) to estimate depth to groundwater contours across the landscape. This will provide accurate contours of depth-to-groundwater along streams and other land surface depressions where GDEs are commonly found.
● Use seasonal data over multiple water year types to capture the variability in environmental conditions inherent in California’s climate, when mapping ISWs. ● Reconcile ISW data gaps with specific measures (shallow monitoring wells, stream gauges, and nested/clustered wells) along surface water features in the Monitoring Network section of the GSP.

Groundwater Dependent Ecosystems
The identification of Groundwater Dependent Ecosystems (GDEs) is insufficient , due to a lack of comprehensive, systematic analysis of the basin’s GDEs.

The GSP uses TNC’s GDE Pulse Tool to describe trends in plant growth (e.g., NDVI) and plant moisture (e.g., NDMI), and provided a map of change in NDMI (Figure 4-16) plotted on NC dataset polygons. Additionally, the GSP provides general discussion of riparian vegetation and depth to groundwater. However, the depth to groundwater data was not directly used to verify the NC dataset polygons.

In particular, we found that some mapped features in the NC dataset were improperly disregarded based on the following:

Bedford-Coldwater Basin Draft GSP Page 4 of 11

● GDEs were disregarded based on the presence or proximity of surface water. However, partial reliance on surface water does not necessarily prove that the plants and animals do not access groundwater. Many GDEs often simultaneously rely on multiple sources of water (i.e., both groundwater and surface water), or shift their reliance on different sources on an interannual or inter-seasonal basis. Additionally, adverse impacts can occur to GDEs due to pumping that further separates groundwater from surface water. ● Mapped features in the NC dataset were disregarded if Normalized Difference Vegetation Index (NDVI) and Normalized Difference Moisture Index (NDMI) data downloaded from GDE Pulse did not correlate with groundwater. This is an incorrect method, since a lack of a relationship does not preclude that groundwater is providing some of the ecosystem's water needs. If the ecosystem is tapping into shallow groundwater then the ecosystem should be categorized as a GDE. If there are no data to characterize groundwater conditions in the shallow principal aquifer, then the GDE should be retained as a potential GDE and data gaps reconciled in the Monitoring Network section of the GSP.

RECOMMENDATIONS
● Develop and describe a systematic approach for analyzing the basin’s GDEs. For example, provide a map of the NC Dataset. On the map, label polygons retained or removed from the NC dataset (and the removal reason if polygons are not considered potential GDEs). Discuss how local groundwater data was used to verify whether polygons in the NC Dataset are supported by groundwater in an aquifer. Refer to Attachment D of this letter for best practices for using local groundwater data to verify whether polygons in the NC Dataset are supported by groundwater in an aquifer. ● Use depth to groundwater data from multiple seasons and water year types (e.g., wet, dry, average, drought) to determine the range of depth to groundwater around NC dataset polygons. We recommend that a baseline period (10 years from 2005 to 2015) be established to characterize groundwater conditions over multiple water year types.

Refer to Attachment D of this letter for best practices for using local groundwater data to verify whether polygons in the NC Dataset are supported by groundwater in an aquifer.
● Provide depth-to-groundwater contour maps, noting the best practices presented in Attachment D. Specifically, ensure that the first step is contouring groundwater elevations, and then subtracting this layer from land surface elevations from a DEM to estimate depth-to-groundwater contours across the landscape. ● If insufficient data are available to describe groundwater conditions within or near polygons from the NC dataset, include those polygons as “Potential GDEs” in the GSP until data gaps are reconciled in the monitoring network. ● Please provide a complete inventory, map, or description of fauna (e.g., birds, fish, amphibian) and flora (e.g., plants) species in the basin and note any threatened or endangered species (see Attachment C in this letter for a list of freshwater species located in the Bedford-Coldwater basin). The GSP provides a habitat map of the federally listed bird species gnatcatcher, but this is the only species referenced under the GDE discussion. The GSP mentions the Western Riverside County Multiple Species Habitat Conservation Plan (MSHCP), but provides few details.

Bedford-Coldwater Basin Draft GSP Page 5 of 11

Native Vegetation and Managed Wetlands
Native vegetation and managed wetlands are water use sectors that are required 1 , 2 to be included into the water budget. The integration of native vegetation into the water budget is sufficient . We commend the GSA for including the groundwater demands of this ecosystem in the historical, current and projected water budgets. Managed wetlands are not mentioned in the GSP, so it is not known whether or not they are present in the basin.

RECOMMENDATION
● State whether or not there are managed wetlands in the basin. If there are, ensure that their groundwater demands are included as separate line items in the historical, current, and projected water budgets.

B. Engaging Stakeholders
Stakeholder Engagement during GSP development
Stakeholder engagement during GSP development is insufficient . SGMA’s requirement for public notice and engagement of stakeholders 3 is not fully met by the description in the Stakeholder Outreach Plan included in the GSP (Appendix D). We note the following deficiencies with the overall stakeholder engagement process:
● The opportunities for public involvement and engagement are described in very general terms. They include attendance at public meetings, stakeholder email list, and updates to the GSP website.
● Domestic well owners are specifically mentioned in the Stakeholder Engagement Plan as holders of overlying groundwater rights, however no information is provided other than stating that their participation is invited in the GSP development process. ● The Stakeholder Outreach Plan does not include a plan for continual opportunities for engagement through the implementation phase of the GSP for tribes and environmental stakeholders.
3 “A communication section of the Plan shall include a requirement that the GSP identify how it encourages the active involvement of diverse social, cultural, and economic elements of the population within the basin.” [23 CCR §354.10(d)(3)]
2 “The water budget shall quantify the following, either through direct measurements or estimates based on data: (3) Outflows from the groundwater system by water use sector, including evapotranspiration, groundwater extraction, groundwater discharge to surface water sources, and subsurface groundwater outflow.” [23 CCR §354.18] 1 “’Water use sector’ refers to categories of water demand based on the general land uses to which the water is applied, including urban, industrial, agricultural, managed wetlands, managed recharge, and native vegetation.” [23 CCR §351(al)]
Bedford-Coldwater Basin Draft GSP Page 6 of 11

RECOMMENDATIONS
● Include a more detailed and robust Stakeholder Outreach Plan that describes active and targeted outreach to engage domestic well owners, environmental stakeholders, and tribal stakeholders during the remainder of the GSP development process and throughout the GSP implementation phase. Refer to Attachment B for specific recommendations on how to actively engage stakeholders during all phases of the GSP process.
● Describe the occurrence of tribal lands in the basin. The GSP states that there are no tribal lands in the basin, but includes four tribes in the list of stakeholders presented in Table 1. If tribes have interests in the basin, describe them in detail. ● Describe efforts to consult and engage with tribes within the basin. Refer to the DWR guidance entitled Engagement with Tribal Governments for specifics on how to consult with tribes. 4
C. Considering Beneficial Uses and Users When Establishing Sustainable Management Criteria and Analyzing Impacts on Beneficial Uses and Users The consideration of beneficial uses and users when establishing sustainable management criteria (SMC) is insufficient . The consideration of potential impacts on all beneficial users of groundwater in the basin are required when defining undesirable results 5 and establishing minimum thresholds. 6 , 7 Disadvantaged Communities and Drinking Water Users
The GSP has aligned the minimum thresholds for contaminants of concern to maximum contaminant levels (MCLs), but has done so by averaging monitored concentrations over a 5-year period and over the entire basin. 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. The monitored concentrations are totaled from each well and then divided by the total number of wells to achieve a single value representing average conditions over the entire Basin. 7 “The description of minimum thresholds shall include [...] how state, federal, or local standards relate to the relevant sustainability indicator. If the minimum threshold differs from other regulatory standards, the agency shall explain the nature of and the basis for the difference.” [23 CCR §354.28(b)(5)] 6 “The description of minimum thresholds shall include [...] how minimum thresholds may affect the interests of beneficial uses and users of groundwater or land uses and property interests.” [23 CCR §354.28(b)(4)] 5 “The description of undesirable results shall include [...] potential effects on the beneficial uses and users of groundwater, on land uses and property interests, and other potential effects that may occur or are occurring from undesirable results.” [23 CCR §354.26(b)(3)]
4 DWR Guidance Document for Engagement with Tribal Governments https://water.ca.gov/-/media/DWR-Website/Web-Pages/Programs/Groundwater-Management/Sustainable-Groundwat er-Management/Best-Management-Practices-and-Guidance-Documents/Files/Guidance-Doc-for-SGM-Engagement- with-Tribal-Govt_ay_19.pdf
Bedford-Coldwater Basin Draft GSP Page 7 of 11

The GSP acknowledges that the method of averaging concentrations (p. 6-25) “is slightly different than the suggested methods to determine sustainability, [but] the GSA desired a single quantitative value to guide management.” Despite this explanation, we still disagree with averaging monitored concentrations over time and space. This is not an adequate methodology since concentrations averaged over 5-years and over the entire basin can not detect impacts to beneficial users of groundwater.

The GSP discounts domestic wells in the setting of SMC, based on the rationale that there are very few private wells in the basin, known private wells are for non-potable use, and responsibility for potential undesirable results to shallow wells is shared between a GSA and a well owner.

Therefore, potential impacts on all beneficial users of groundwater in the basin have not been considered when defining undesirable results and establishing minimum thresholds.

RECOMMENDATIONS
Chronic Lowering of Groundwater Levels
● Consider and evaluate the impacts of selected minimum thresholds and measurable objectives on drinking water users within the basin. Further describe the impact of passing the minimum threshold for drinking water users. For example, provide the number of domestic wells that would be de-watered at the minimum threshold.

Degraded Water Quality
● Set minimum thresholds for degraded water quality that are compared to individually monitored concentrations, not those that are averaged over time or space. ● Describe direct and indirect impacts on drinking water users when defining undesirable results for degraded water quality. For specific guidance on how to consider domestic water users, refer to “Guide to Protecting Water Quality Under the Sustainable Groundwater Management Act.” 8
● Evaluate the cumulative or indirect impacts of proposed minimum thresholds for TDS and nitrate on drinking water users.
● Provide distinct maps for PFOS, PFOA and sulfate contamination plumes as required in SGMA regulations 9
.

Groundwater Dependent Ecosystems and Interconnected Surface Waters The GSP uses 2014-2016 groundwater elevations as minimum thresholds for the depletion of interconnected surface water SMC (using groundwater elevations as proxy). We are concerned that this will not avoid undesirable results to environmental beneficial users. The true impacts to ecosystems under this scenario are not fully discussed in the GSP. If minimum thresholds are set to historic low groundwater levels and the subbasin is allowed to operate just above or close to those levels over many years, there is a risk of causing catastrophic damage to ecosystems that are more adverse than what was occurring at the height of the 2012-2016 drought. This is because California ecosystems, which are adapted to our Mediterranean climate, have some 9 “Groundwater quality issues that may affect the supply and beneficial uses of groundwater, including a description and map of the location of known groundwater contamination sites and plumes.” [23 CCR §354.16(d)] 8 Guide to Protecting Water Quality under the Sustainable Groundwater Management Act https://d3n8a8pro7vhmx.cloudfront.net/communitywatercenter/pages/293/attachments/original/1559328858/Guide_to _Protecting_Drinking_Water_Quality_Under_the_Sustainable_Groundwater_Management_Act.pdf?1559328858.

Bedford-Coldwater Basin Draft GSP Page 8 of 11

drought strategies that they can utilize to deal with short-term water stress. However, if the drought conditions are prolonged, the ecosystem can collapse.

The GSP states (p. 6-37) that “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.” The basin’s ecosystems could be further damaged or even destroyed if groundwater conditions are maintained just above those levels in the long-term, since the subbasin would be permitted to sustain extreme dry conditions over multiple seasons and years.

RECOMMENDATIONS
● Define chronic lowering of groundwater SMC directly for environmental beneficial users of groundwater. GDEs are discussed only in relation to the depletions of interconnected surface water SMC (using groundwater elevations as proxy for depletions of interconnected surface waters), but not directly for the chronic lowering of groundwater SMC.
● When defining undesirable results for chronic lowering of groundwater levels and depletions of interconnected surface waters, provide specifics on what biological responses (e.g., extent of habitat, growth, recruitment rates) would best characterize a significant and unreasonable impact to GDEs. Undesirable results to environmental users occur when ‘significant and unreasonable’ effects on beneficial users are caused by groundwater conditions in the subbasin. Thus, potential impacts on environmental beneficial uses and users need to be considered when defining undesirable results 10 in the subbasin. Defining undesirable results is the crucial first step before the minimum thresholds 11 can be determined.

2. Climate Change
The SGMA statute identifies climate change as a significant threat to groundwater resources and one that must be examined and incorporated in the GSPs. The GSP Regulations 12 require integration of climate change into the projected water budget to ensure that projects and management actions sufficiently account for the range of potential climate futures.

The integration of climate change into the projected water budget is insufficient . The GSP does incorporate climate change into the projected water budget using DWR change factors for 2070.

However, the GSP did not consider the 2070 extremely wet and extremely dry climate scenarios in the projected water budget. The GSP should clearly and transparently incorporate the extremely wet and dry scenarios provided by DWR into projected water budgets or select more appropriate extreme scenarios 12 “Each Plan shall rely on the best available information and best available science to quantify the water budget for the basin in order to provide an understanding of historical and projected hydrology, water demand, water supply, land use, population, climate change, sea level rise, groundwater and surface water interaction, and subsurface groundwater flow.” [23 CCR §354.18(e)]
11 The description of minimum thresholds shall include [...] how minimum thresholds may affect the interests of beneficial uses and users of groundwater or land uses and property interests.” [23 CCR §354.28(b)(4)] 10 “The description of undesirable results shall include [...] potential effects on the beneficial uses and users of groundwater, on land uses and property interests, and other potential effects that may occur or are occurring from undesirable results”. [23 CCR §354.26(b)(3)]
Bedford-Coldwater Basin Draft GSP Page 9 of 11

for their basins. While these extreme scenarios may have a lower likelihood of occurring, their consequences could be significant, therefore they should be included in groundwater planning.

We acknowledge and commend the inclusion of climate change into key inputs (precipitation, evaporation, and surface water flow) of the projected water budget. Additionally, the sustainable yield is calculated based on the projected pumping for future projections that include climate change. However, if the water budgets are incomplete, including the omission of extremely wet and dry scenarios, then there is increased uncertainty in virtually every subsequent calculation used to plan for projects, derive measurable objectives, and set minimum thresholds. Plans that do not adequately include climate change projections may underestimate future impacts on vulnerable beneficial users of groundwater such as ecosystems and domestic well owners.

RECOMMENDATIONS
● Integrate extreme wet and dry scenarios into the projected water budget to form the basis for development of sustainable management criteria and projects and management actions.
● Incorporate climate change scenarios into projects and management actions.

3. Data Gaps
The consideration of beneficial users when establishing monitoring networks is insufficient . Without adequate monitoring and identification of data gaps, beneficial users of groundwater including GDEs, surface water users, and drinking water users will remain unprotected by the GSP. The Plan therefore fails to meet SGMA’s requirements for the monitoring network 13 . We recommend the following steps to ensure that the monitoring network is protective of all beneficial users of groundwater.

RECOMMENDATIONS
● Provide maps that overlay monitoring well locations with the locations of GDEs and domestic wells to clearly identify potentially impacted areas. Ensure that existing and proposed representative monitoring sites adequately cover portions of the basin with GDEs and domestic wells.
● Provide a detailed plan for the investigation of shallow groundwater/surface water interaction at Temescal Wash as discussed in Section 8.6, instead of leaving this for a future project. Reconcile data gaps in the monitoring network by evaluating how the gathered data will be used to identify and map GDEs and ISWs. 13 “The monitoring network objectives shall be implemented to accomplish the following: [...] (2) Monitor impacts to the beneficial uses or users of groundwater.” [23 CCR §354.34(b)(2)] Bedford-Coldwater Basin Draft GSP Page 10 of 11

● Determine what ecological monitoring can be used to assess the potential for significant and unreasonable impacts to GDEs or ISWs due to groundwater conditions in the subbasin. The GSP mentions biological surveys in Section 8.6, but no details are given.

4. Addressing Beneficial Users in Projects and Management Actions The consideration of beneficial users when developing projects and management actions is insufficient , due to lack of identification of benefits or impacts of identified projects and management actions to key beneficial users of groundwater such as GDEs, surface water users, and drinking water users. Therefore, potential project and management actions may not protect these beneficial users. Groundwater sustainability under SGMA is defined not just by sustainable yield, but by the avoidance of undesirable results for all beneficial users.

RECOMMENDATIONS
Because GDEs, aquatic habitats, surface water users, and drinking water users were not sufficiently identified in the GSP, please consider including the following related to potential project and management actions in the GSP:
● Recharge ponds, reservoirs and facilities for managed stormwater recharge can be designed as multiple-benefit projects to include elements that act functionally as wetlands and provide a benefit for wildlife and aquatic species. For guidance on how to integrate multi-benefit recharge projects into your GSP refer to the “Multi-Benefit Recharge Project Methodology Guidance Document” 14 .
● For domestic well owners, include discussion of a drinking water well impact mitigation program to proactively monitor and protect drinking water wells through GSP implementation. Refer to Attachment B for specific recommendations on how to implement a drinking water well mitigation program.
● For domestic well owners, include a discussion of whether potential impacts to water quality from projects and management actions could occur and how the GSA plans to mitigate such impacts.
● Develop management actions that incorporate climate and water delivery uncertainties to address future water demand and prevent future undesirable results. 14 The Nature Conservancy. 2021. Multi-Benefit Recharge Project Methodology for Inclusion in Groundwater Sustainability Plans. Sacramento. Available at:
https://groundwaterresourcehub.org/sgma-tools/multi-benefit-recharge-project-methodology-guidance/ Bedford-Coldwater Basin Draft GSP Page 11 of 11

Attachment B
SGMA Tools to address DAC, drinking water, and
environmental beneficial uses and users
Stakeholder Engagement and Outreach
Clean Water Action, Community Water Center and Union of Concerned Scientists developed a guidance document
called Collaborating for success: Stakeholder engagement for Sustainable Groundwater Management Act
Implementation. It provides details on how to conduct
targeted and broad outreach and engagement during
Groundwater Sustainability Plan (GSP) development and
implementation. Conducting a targeted outreach involves:
• Developing a robust Stakeholder Communication and Engagement plan that includes outreach at frequented locations (schools, farmers markets, religious settings, events) across the plan area to increase the involvement and participation of disadvantaged communities, drinking water users and the environmental stakeholders. • Providing translation services during meetings and technical assistance to enable easy participation for non-English speaking stakeholders.
• GSP should adequately describe the process for requesting input from beneficial users and provide details on how input is incorporated into the GSP.

The Human Right to Water
The Human Right to Water Scorecard was developed
by Community Water Center, Leadership Counsel for
Justice and Accountability and Self Help Enterprises to aid Groundwater Sustainability Agencies (GSAs) in
prioritizing drinking water needs in SGMA. The
scorecard identifies elements that must exist in GSPs
to adequately protect the Human Right to Drinking
water.

Drinking Water Well Impact Mitigation Framework
The Drinking Water Well Impact Mitigation
Framework was developed by Community Water
Center, Leadership Counsel for Justice and
Accountability and Self Help Enterprises to aid
GSAs in the development and implementation of
their GSPs. The framework provides a clear
roadmap for how a GSA can best structure its
data gathering, monitoring network and
management actions to proactively monitor and
protect drinking water wells and mitigate impacts
should they occur.

Groundwater Resource Hub
The Nature Conservancy has
developed a suite of tools based on
best available science to help GSAs,
consultants, and stakeholders
efficiently incorporate nature into
GSPs. These tools and resources are
available online at
GroundwaterResourceHub.org. The
Nature Conservancy’s tools and
resources are intended to reduce
costs, shorten timelines, and increase
benefits for both people and nature.

Rooting Depth Database
The Plant Rooting Depth Database provides information that can help assess whether groundwater-dependent vegetation are accessing groundwater. Actual rooting depths will depend on the plant species and site-specific conditions, such as soil type and

availability of other water sources. Site-specific knowledge of depth to groundwater combined with rooting depths will help provide an understanding of the potential groundwater levels are needed to sustain GDEs.

How to use the database
The maximum rooting depth information in the Plant Rooting Depth Database is useful when verifying whether vegetation in the Natural Communities Commonly Associated with Groundwater (NC Dataset) are connected to groundwater. A 30 ft depth-togroundwater threshold, which is based on averaged global rooting depth data for phreatophytes1, is relevant for most plants identified in the NC Dataset since most plants have a max rooting depth of less than 30 feet. However, it is important to note that deeper thresholds are necessary for other plants that have reported maximum root depths that exceed the averaged 30 feet threshold, such as valley oak (Quercus lobata), Euphrates poplar (Populus euphratica), salt cedar (Tamarix spp.), and shadescale (Atriplex confertifolia). The Nature Conservancy advises that the reported max rooting depth for these deeper-rooted plants be used. For example, a depth-to groundwater threshold of 80 feet should be used instead of the 30 ft threshold, when verifying whether valley oak polygons from the NC Dataset are connected to groundwater. It is important to re-emphasize that actual rooting depth data are limited and will depend on the plant species and site-specific conditions such as soil and aquifer types, and availability to other water sources.

The Plant Rooting Depth Database is an Excel workbook composed of four worksheets:

1. California phreatophyte rooting depth data (included in the NC Dataset)

2. Global phreatophyte rooting depth data

3. Metadata

4. References
How the database was compiled
The Plant Rooting Depth Database is a compilation of rooting depth information for the groundwater-dependent plant species identified in the NC Dataset. Rooting depth data were compiled from published scientific literature and expert opinion through a crowdsourcing campaign. As more information becomes available, the database of rooting depths will be updated. Please Contact Us if you have additional rooting depth data for California phreatophytes.
1 Canadell, J., Jackson, R.B., Ehleringer, J.B. et al. 1996. Maximum rooting depth of vegetation types at the global scale. Oecologia 108, 583–595. https://doi.org/10.1007/BF00329030

GDE Pulse
GDE Pulse is a free online tool that allows Groundwater Sustainability Agencies to assess changes in groundwater dependent ecosystem (GDE) health using satellite, rainfall, and groundwater data. Remote sensing data from satellites has been used to monitor the health of vegetation all over the planet. GDE pulse has compiled 35 years of satellite imagery from NASA’s Landsat mission for every polygon in the Natural Communities Commonly Associated with Groundwater Dataset. The following datasets are available for downloading:

Normalized Difference Vegetation Index (NDVI) is a satellite-derived index that represents the greenness of vegetation. Healthy green vegetation tends to have a higher NDVI, while dead leaves have a lower NDVI. We calculated the average NDVI during the driest part of the year (July - Sept) to estimate vegetation health when the plants are most likely dependent on groundwater.

Normalized Difference Moisture Index (NDMI) is a satellite-derived index that represents water content in vegetation. NDMI is derived from the Near-Infrared (NIR) and Short-Wave Infrared (SWIR) channels. Vegetation with adequate access to water tends to have higher NDMI, while vegetation that is water stressed tends to have lower NDMI. We calculated the average NDVI during the driest part of the year (July– September) to estimate vegetation health when the plants are most likely dependent on groundwater.

Annual Precipitation is the total precipitation for the water year (October 1st – September 30th) from the PRISM dataset. The amount of local precipitation can affect vegetation with more precipitation generally leading to higher NDVI and NDMI.

Depth to Groundwater measurements provide an indication of the groundwater levels and changes over time for the surrounding area. We used groundwater well measurements from nearby (<1km) wells to estimate the depth to groundwater below the GDE based on the average elevation of the GDE (using a digital elevation model) minus the measured groundwater surface elevation.

ICONOS Mapper
Interconnected Surface Water in the Central Valley
ICONS maps the likely presence of interconnected surface water (ISW) in the Central Valley using depth to groundwater data. Using data from 2011-2018, the ISW dataset represents the likely connection between surface water and groundwater for rivers and streams in California’s Central Valley. It includes information on the mean, maximum, and minimum depth to groundwater for each stream segment over the years with available data, as well as the likely presence of ISW based on the minimum depth to groundwater. The Nature Conservancy developed this database, with guidance and input from expert academics, consultants, and state agencies.

We developed this dataset using groundwater elevation data available online from the California Department of Water Resources (DWR). DWR only provides this data for the Central Valley. For GSAs outside of the valley, who have groundwater well measurements, we recommend following our methods to determine likely ISW in your region. The Nature Conservancy’s ISW dataset should be used as a first step in reviewing ISW and should be supplemented with local or more recent groundwater depth data.

Attachment C
Freshwater Species Located in the Bedford-Coldwater Subbasin To assist in identifying the beneficial users of surface water necessary to assess the undesirable result “depletion of interconnected surface waters”, Attachment C provides a list of freshwater species located in the Bedford-Coldwater Subbasin. To produce the freshwater species list, we used ArcGIS to select features within the California Freshwater Species Database version 2.0.9 within the basin boundary. This database contains information on ~4,000 vertebrates, macroinvertebrates and vascular plants that depend on fresh water for at least one stage of their life cycle. The methods used to compile the California Freshwater Species Database can be found in Howard et al. 20151. The spatial database contains locality observations and/or distribution information from ~400 data sources. The database is housed in the California Department of Fish and Wildlife’s BIOS2 as well as on The Nature Conservancy’s science website3.

Scientific Name Common Name Legal Protected Status
Federal State Other
BIRDS
Icteria virens Yellow-breasted Chat Special Concern BSSC - Third priority
Vireo bellii pusillus Least Bell's Vireo Endangered Endangered Anas platyrhynchos Mallard
Ardea alba Great Egret
Ardea herodias Great Blue Heron
Butorides virescens Green Heron
Egretta thula Snowy Egret
Himantopus
mexicanus Black-necked Stilt
Megaceryle alcyon Belted Kingfisher
Oxyura jamaicensis Ruddy Duck
Pelecanus
erythrorhynchos
American White
Pelican Special Concern BSSC - First priority
Phalacrocorax
auritus
Double-crested
Cormorant
Podilymbus podiceps Pied-billed Grebe
Setophaga petechia Yellow Warbler BSSC - Second
priority

CRUSTACEANS
Crangonyx spp. Crangonyx spp.

Hyalella spp. Hyalella spp.

HERPS
Actinemys
marmorata
marmorata
Western Pond Turtle Special Concern ARSSC
Anaxyrus boreas
boreas Boreal Toad
1 Howard, J.K. et al. 2015. Patterns of Freshwater Species Richness, Endemism, and Vulnerability in California.

PLoSONE, 11(7). Available at: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0130710 2 California Department of Fish and Wildlife BIOS: https://www.wildlife.ca.gov/data/BIOS 3 Science for Conservation: https://www.scienceforconservation.org/products/california-freshwater-speciesdatabase

Anaxyrus californicus Arroyo Toad Endangered Special Concern ARSSC Pseudacris
cadaverina California Treefrog ARSSC
Rana draytonii California Red-legged
Frog Threatened Special Concern ARSSC
Spea hammondii Western Spadefoot
Under
Review in
the
Candidate or
Petition
Process
Special Concern ARSSC
Taricha torosa Coast Range Newt Special Concern ARSSC
Thamnophis
hammondii
hammondii
Two-striped
Gartersnake Special Concern ARSSC
Thamnophis sirtalis
sirtalis Common Gartersnake

INSECTS & OTHER INVERTS
Alotanypus spp. Alotanypus spp.

Argia spp. Argia spp.

Baetis adonis A Mayfly
Baetis spp. Baetis spp.

Cheumatopsyche
spp. Cheumatopsyche spp.

Chironomidae fam. Chironomidae fam.

Coenagrionidae fam. Coenagrionidae fam.

Cricotopus bicinctus Not on any status
lists
Cricotopus trifascia Not on any status
lists
Dicrotendipes spp. Dicrotendipes spp.

Eukiefferiella spp. Eukiefferiella spp.

Hetaerina spp. Hetaerina spp.

Hydropsyche spp. Hydropsyche spp.

Hydroptila spp. Hydroptila spp.

Hydroptilidae fam. Hydroptilidae fam.

Labrundinia spp. Labrundinia spp.

Libellulidae fam. Libellulidae fam.

Limnophyes spp. Limnophyes spp.

Micrasema spp. Micrasema spp.

Microtendipes spp. Microtendipes spp.

Nectopsyche spp. Nectopsyche spp.

Ochrotrichia spp. Ochrotrichia spp.

Parametriocnemus
spp.

Parametriocnemus
spp.

Paraphaenocladius
spp.

Paraphaenocladius
spp.

Paratendipes spp. Paratendipes spp.

Pentaneura spp. Pentaneura spp.

Phaenopsectra spp. Phaenopsectra spp.

Polypedilum spp. Polypedilum spp.

Procladius spp. Procladius spp.

Pseudochironomus
spp.

Pseudochironomus
spp.

Rheotanytarsus spp. Rheotanytarsus spp.

Simulium spp. Simulium spp.

Sperchon spp. Sperchon spp.

Tanytarsus spp. Tanytarsus spp.

Thienemannimyia
spp. Thienemannimyia spp.

Tinodes spp. Tinodes spp.

Tipulidae fam. Tipulidae fam.

Tribelos spp. Tribelos spp.

Tricorythodes spp. Tricorythodes spp.

MOLLUSKS
Ferrissia spp. Ferrissia spp.

Lymnaea spp. Lymnaea spp.

Menetus opercularis Button Sprite CS
Physa spp. Physa spp.

Planorbidae fam. Planorbidae fam.

PLANTS
Baccharis salicina Not on any status
lists
Cyperus
erythrorhizos Red-root Flatsedge
Mimulus guttatus Common Large
Monkeyflower
Mimulus pilosus Not on any status
lists
Phacelia distans NA
Plagiobothrys
acanthocarpus Adobe Popcorn-flower
Platanus racemosa California Sycamore
Pluchea odorata
odorata Scented Conyza
Pluchea sericea Arrow-weed
Rorippa palustris
palustris Bog Yellowcress
Rumex salicifolius
salicifolius Willow Dock
Salix gooddingii Goodding's Willow
Salix laevigata Polished Willow
Salix lasiandra
lasiandra
Not on any status
lists
Veronica anagallisaquatica NA

1 July 2019
IDENTIFYING GDEs UNDER SGMA
Best Practices for using the NC Dataset
The Sustainable Groundwater Management Act (SGMA) requires that groundwater dependent ecosystems (GDEs) be identified in Groundwater Sustainability Plans (GSPs). As a starting point, the Department of Water Resources (DWR) is providing the Natural Communities Commonly Associated with Groundwater Dataset (NC Dataset) online1 to help Groundwater Sustainability Agencies (GSAs), consultants, and stakeholders identify GDEs within individual groundwater basins. To apply information from the NC Dataset to local areas, GSAs should combine it with the best available science on local hydrology, geology, and groundwater levels to verify whether polygons in the NC dataset are likely supported by groundwater in an aquifer (Figure 1)2. This document highlights six best practices for using local groundwater data to confirm whether mapped features in the NC dataset are supported by groundwater.
1 NC Dataset Online Viewer: https://gis.water.ca.gov/app/NCDatasetViewer/ 2 California Department of Water Resources (DWR). 2018. Summary of the “Natural Communities Commonly Associated with Groundwater” Dataset and Online Web Viewer. Available at: https://water.ca.gov/-/media/DWR-Website/WebPages/Programs/Groundwater-Management/Data-and-Tools/Files/Statewide-Reports/Natural-Communities-DatasetSummary-Document.pdf Figure 1. Considerations for GDE identification.

Source: DWR2
Attachment D

2 The NC Dataset identifies vegetation and wetland features that are good indicators of a GDE. The dataset is comprised of 48 publicly available state and federal datasets that map vegetation, wetlands, springs, and seeps commonly associated with groundwater in California3. It was developed through a collaboration between DWR, the Department of Fish and Wildlife, and The Nature Conservancy (TNC).

TNC has also provided detailed guidance on identifying GDEs from the NC dataset4 on the Groundwater Resource Hub5, a website dedicated to GDEs.

BEST PRACTICE #1. Establishing a Connection to Groundwater Groundwater basins can be comprised of one continuous aquifer (Figure 2a) or multiple aquifers stacked on top of each other (Figure 2b). In unconfined aquifers (Figure 2a), using the depth-to-groundwater and the rooting depth of the vegetation is a reasonable method to infer groundwater dependence for GDEs. If groundwater is well below the rooting (and capillary) zone of the plants and any wetland features, the ecosystem is considered disconnected and groundwater management is not likely to affect the ecosystem (Figure 2d). However, it is important to consider local conditions (e.g., soil type, groundwater flow gradients, and aquifer parameters) and to review groundwater depth data from multiple seasons and water year types (wet and dry) because intermittent periods of high groundwater levels can replenish perched clay lenses that serve as the water source for GDEs (Figure 2c). Maintaining these natural groundwater fluctuations are important to sustaining GDE health.

Basins with a stacked series of aquifers (Figure 2b) may have varying levels of pumping across aquifers in the basin, depending on the production capacity or water quality associated with each aquifer. If pumping is concentrated in deeper aquifers, SGMA still requires GSAs to sustainably manage groundwater resources in shallow aquifers, such as perched aquifers, that support springs, surface water, domestic wells, and GDEs (Figure 2). This is because vertical groundwater gradients across aquifers may result in pumping from deeper aquifers to cause adverse impacts onto beneficial users reliant on shallow aquifers or interconnected surface water. The goal of SGMA is to sustainably manage groundwater resources for current and future social, economic, and environmental benefits. While groundwater pumping may not be currently occurring in a shallower aquifer, use of this water may become more appealing and economically viable in future years as pumping restrictions are placed on the deeper production aquifers in the basin to meet the sustainable yield and criteria. Thus, identifying GDEs in the basin should done irrespective to the amount of current pumping occurring in a particular aquifer, so that future impacts on GDEs due to new production can be avoided. A good rule of thumb to follow is: if groundwater can be pumped from a well - it’s an aquifer.

3 For more details on the mapping methods, refer to: Klausmeyer, K., J. Howard, T. Keeler-Wolf, K. Davis-Fadtke, R. Hull, A. Lyons. 2018. Mapping Indicators of Groundwater Dependent Ecosystems in California: Methods Report. San Francisco, California. Available at: https://groundwaterresourcehub.org/public/uploads/pdfs/iGDE_data_paper_20180423.pdf 4 “Groundwater Dependent Ecosystems under the Sustainable Groundwater Management Act: Guidance for Preparing Groundwater Sustainability Plans” is available at: https://groundwaterresourcehub.org/gde-tools/gsp-guidance-document/ 5 The Groundwater Resource Hub: www.GroundwaterResourceHub.org

3 Figure 2. Confirming whether an ecosystem is connected to groundwater. Top: (a) Under the ecosystem is an unconfined aquifer with depth-to-groundwater fluctuating seasonally and interannually within 30 feet from land surface. (b) Depth-to-groundwater in the shallow aquifer is connected to overlying ecosystem. Pumping predominately occurs in the confined aquifer, but pumping is possible in the shallow aquifer. Bottom: (c) Depthto-groundwater fluctuations are seasonally and interannually large, however, clay layers in the near surface prolong the ecosystem’s connection to groundwater. (d) Groundwater is disconnected from surface water, and any water in the vadose (unsaturated) zone is due to direct recharge from precipitation and indirect recharge under the surface water feature. These areas are not connected to groundwater and typically support species that do not require access to groundwater to survive.

4 BEST PRACTICE #2. Characterize Seasonal and Interannual Groundwater Conditions SGMA requires GSAs to describe current and historical groundwater conditions when identifying GDEs [23 CCR §354.16(g)]. Relying solely on the SGMA benchmark date (January 1, 2015) or any other single point in time to characterize groundwater conditions (e.g., depth-to-groundwater) is inadequate because managing groundwater conditions with data from one time point fails to capture the seasonal and interannual variability typical of California’s climate. DWR’s Best Management Practices document on water budgets6 recommends using 10 years of water supply and water budget information to describe how historical conditions have impacted the operation of the basin within sustainable yield, implying that a baseline7 could be determined based on data between 2005 and 2015. Using this or a similar time period, depending on data availability, is recommended for determining the depth-to-groundwater.

GDEs depend on groundwater levels being close enough to the land surface to interconnect with surface water systems or plant rooting networks. The most practical approach8 for a GSA to assess whether polygons in the NC dataset are connected to groundwater is to rely on groundwater elevation data. As detailed in TNC’s GDE guidance document4, one of the key factors to consider when mapping GDEs is to contour depth-to-groundwater in the aquifer that is supporting the ecosystem (see Best Practice #5).

Groundwater levels fluctuate over time and space due to California’s Mediterranean climate (dry summers and wet winters), climate change (flood and drought years), and subsurface heterogeneity in the subsurface (Figure 3). Many of California’s GDEs have adapted to dealing with intermittent periods of water stress, however if these groundwater conditions are prolonged, adverse impacts to GDEs can result. While depth-to-groundwater levels within 30 feet4 of the land surface are generally accepted as being a proxy for confirming that polygons in the NC dataset are supported by groundwater, it is highly advised that fluctuations in the groundwater regime be characterized to understand the seasonal and interannual groundwater variability in GDEs. Utilizing groundwater data from one point in time can misrepresent groundwater levels required by GDEs, and inadvertently result in adverse impacts to the GDEs. Time series data on groundwater elevations and depths are available on the SGMA Data Viewer9.

However, if insufficient data are available to describe groundwater conditions within or near polygons from the NC dataset, include those polygons in the GSP until data gaps are reconciled in the monitoring network (see Best Practice #6).

Figure 3. Example seasonality
and interannual variability in
depth-to-groundwater over
time. Selecting one point in time,
such as Spring 2018, to
characterize groundwater
conditions in GDEs fails to capture
what groundwater conditions are
necessary to maintain the
ecosystem status into the future so
adverse impacts are avoided.

6 DWR. 2016. Water Budget Best Management Practice. Available at:
https://water.ca.gov/LegacyFiles/groundwater/sgm/pdfs/BMP_Water_Budget_Final_2016-12-23.pdf 7 Baseline is defined under the GSP regulations as “historic information used to project future conditions for hydrology, water demand, and availability of surface water and to evaluate potential sustainable management practices of a basin.” [23 CCR §351(e)] 8 Groundwater reliance can also be confirmed via stable isotope analysis and geophysical surveys. For more information see The GDE Assessment Toolbox (Appendix IV, GDE Guidance Document for GSPs4). 9 SGMA Data Viewer: https://sgma.water.ca.gov/webgis/?appid=SGMADataViewer

5 BEST PRACTICE #3. Ecosystems Often Rely on Both Groundwater and Surface Water GDEs are plants and animals that rely on groundwater for all or some of its water needs, and thus can be supported by multiple water sources. The presence of non-groundwater sources (e.g., surface water, soil moisture in the vadose zone, applied water, treated wastewater effluent, urban stormwater, irrigated return flow) within and around a GDE does not preclude the possibility that it is supported by groundwater, too. SGMA defines GDEs as "ecological communities and species that depend on groundwater emerging from aquifers or on groundwater occurring near the ground surface" [23 CCR §351(m)]. Hence, depth-to-groundwater data should be used to identify whether NC polygons are supported by groundwater and should be considered GDEs. In addition, SGMA requires that significant and undesirable adverse impacts to beneficial users of surface water be avoided. Beneficial users of surface water include environmental users such as plants or animals10, which therefore must be considered when developing minimum thresholds for depletions of interconnected surface water.

GSAs are only responsible for impacts to GDEs resulting from groundwater conditions in the basin, so if adverse impacts to GDEs result from the diversion of applied water, treated wastewater, or irrigation return flow away from the GDE, then those impacts will be evaluated by other permitting requirements (e.g., CEQA) and may not be the responsibility of the GSA. However, if adverse impacts occur to the GDE due to changing groundwater conditions resulting from pumping or groundwater management activities, then the GSA would be responsible (Figure 4).

Figure 4. Ecosystems often depend on multiple sources of water. Top: (Left) Surface water and groundwater are interconnected, meaning that the GDE is supported by both groundwater and surface water. (Right) Ecosystems that are only reliant on non-groundwater sources are not groundwater-dependent. Bottom: (Left) An ecosystem that was once dependent on an interconnected surface water, but loses access to groundwater solely due to surface water diversions may not be the GSA’s responsibility. (Right) Groundwater dependent ecosystems once dependent on an interconnected surface water system, but loses that access due to groundwater pumping is the GSA’s responsibility.

10 For a list of environmental beneficial users of surface water by basin, visit: https://groundwaterresourcehub.org/gdetools/environmental-surface-water-beneficiaries/

6 BEST PRACTICE #4. Select Representative Groundwater Wells Identifying GDEs in a basin requires that groundwater conditions are characterized to confirm whether polygons in the NC dataset are supported by the underlying aquifer. To do this, proximate groundwater wells should be identified to characterize groundwater conditions (Figure 5). When selecting representative wells, it is particularly important to consider the subsurface heterogeneity around NC polygons, especially near surface water features where groundwater and surface water interactions occur around heterogeneous stratigraphic units or aquitards formed by fluvial deposits. The following selection criteria can help ensure groundwater levels are representative of conditions within the GDE area:
● Choose wells that are within 5 kilometers (3.1 miles) of each NC Dataset polygons because they are more likely to reflect the local conditions relevant to the ecosystem. If there are no wells within 5km of the center of a NC dataset polygon, then there is insufficient information to remove the polygon based on groundwater depth. Instead, it should be retained as a potential GDE until there are sufficient data to determine whether or not the NC Dataset polygon is supported by groundwater.
● Choose wells that are screened within the surficial unconfined aquifer and capable of measuring the true water table.
● Avoid relying on wells that have insufficient information on the screened well depth interval for excluding GDEs because they could be providing data on the wrong aquifer. This type of well data should not be used to remove any NC polygons.

Figure 5. Selecting representative wells to characterize groundwater conditions near GDEs.

7 BEST PRACTICE #5. Contouring Groundwater Elevations
The common practice to contour depth-to-groundwater over a large area by interpolating measurements at monitoring wells is unsuitable for assessing whether an ecosystem is supported by groundwater. This practice causes errors when the land surface contains features like stream and wetland depressions because it assumes the land surface is constant across the landscape and depth-to-groundwater is constant below these low-lying areas (Figure 6a). A more accurate approach is to interpolate groundwater elevations at monitoring wells to get groundwater elevation contours across the landscape. This layer can then be subtracted from land surface elevations from a Digital Elevation Model (DEM)11 to estimate depth-to-groundwater contours across the landscape (Figure b; Figure 7). This will provide a much more accurate contours of depth-to-groundwater along streams and other land surface depressions where GDEs are commonly found.

Figure 6. Contouring depth-to-groundwater around surface water features and GDEs. (a) Groundwater level interpolation using depth-to-groundwater data from monitoring wells. (b) Groundwater level interpolation using groundwater elevation data from monitoring wells and DEM data.

Figure 7. Depth-to-groundwater contours in Northern California. (Left) Contours were interpolated using depth-to-groundwater measurements determined at each well. (Right) Contours were determined by interpolating groundwater elevation measurements at each well and superimposing ground surface elevation from DEM spatial data to generate depth-to-groundwater contours. The image on the right shows a more accurate depth-togroundwater estimate because it takes the local topography and elevation changes into account.

11 USGS Digital Elevation Model data products are described at: https://www.usgs.gov/core-sciencesystems/ngp/3dep/about-3dep-products-services and can be downloaded at: https://iewer.nationalmap.gov/basic/

8 BEST PRACTICE #6. Best Available Science
Adaptive management is embedded within SGMA and provides a process to work toward sustainability over time by beginning with the best available information to make initial decisions, monitoring the results of those decisions, and using the data collected through monitoring programs to revise decisions in the future. In many situations, the hydrologic connection of NC dataset polygons will not initially be clearly understood if site-specific groundwater monitoring data are not available. If sufficient data are not available in time for the 2020/2022 plan, The Nature Conservancy strongly advises that questionable polygons from the NC dataset be included in the GSP until data gaps are reconciled in the monitoring network. Erring on the side of caution will help minimize inadvertent impacts to GDEs as a result of groundwater use and management actions during SGMA implementation.

ABOUT US
The Nature Conservancy is a science-based nonprofit organization whose mission is to conserve the lands and waters on which all life depends. To support successful SGMA implementation that meets the future needs of people, the economy, and the environment, TNC has developed tools and resources (www.groundwaterresourcehub.org) intended to reduce costs, shorten timelines, and increase benefits for both people and nature.

KEY DEFINITIONS
Groundwater basin is an aquifer or stacked series of aquifers with reasonably welldefined boundaries in a lateral direction, based on features that significantly impede groundwater flow, and a definable bottom. 23 CCR §341(g)(1) Groundwater dependent ecosystem (GDE) are ecological communities or species that depend on groundwater emerging from aquifers or on groundwater occurring near the ground surface. 23 CCR §351(m)
Interconnected surface water (ISW) surface water that is hydraulically connected at any point by a continuous saturated zone to the underlying aquifer and the overlying surface water is not completely depleted. 23 CCR §351(o) Principal aquifers are aquifers or aquifer systems that store, transmit, and yield significant or economic quantities of groundwater to wells, springs, or surface water systems. 23 CCR §351(aa)

1 Board Members:

Paul Rodriguez, TVWD
Jacque Casillas, City of Corona
Phil Williams, EVMWD
November 1, 2021
To: Ngoro Atume – Clean Water Action/Clean Water Fund
Dr. J. Pablo Ortiz-Partida – Union of Concerned Scientists Samantha Arthur – Audubon California
Danielle V. Dolan – Local Government Commission
E.J. Remson – The Nature Conservancy (TNC)
Melissa M. Rohde – The Nature Conservancy
Via email
RE: Public Comment Letter for the Bedford-Coldwater Basin Draft GSP Dated September 6, 2021 The Bedford-Coldwater Groundwater Sustainability Agency (BCGSA) appreciates your thorough review of our Groundwater Sustainability Plan (GSP). Throughout the process, the BCGSA has encouraged and welcomed public input, including the comment letter you submitted September 6, 2021. We have reviewed your comments and are editing the Bedford-Coldwater GSP in response to them. In addition, detailed responses to your comments are provided below. Your September 6 comment letter is attached for reference.

1. Comment: “Beneficial uses and users are not sufficiently considered in GSP development” Beneficial uses and users have been considered throughout the GSP. We are adding text to Chapter 2 of the GSP to more completely document groundwater users in the Basin.

A. Comment: “Human Right to Water considerations are not sufficiently incorporated.” Disadvantaged Communities, Drinking Water Users, and Tribes There are no disadvantaged communities (DACS) or tribal lands in the Basin, and the BCGSA believes there are very few active private wells, none of which are used for potable water supply in the Basin. We have clarified and added text in the Executive Summary and Chapters 2, 5 and 6 in response to your comment.

DACs
No DACs or severely disadvantaged communities (SDACs) have been identified in the Basin.

Tribal Lands
The comment takes issue with the statement that there are no tribal lands in the Basin when tribal entities were included in the list of stakeholders. 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

2 Board Members:

Paul Rodriguez, TVWD
Jacque Casillas, City of Corona
Phil Williams, EVMWD
and regional tribal entities coordinate to assess infrastructure project sites prior to groundbreaking to identify and protect potential cultural resources.

Comment: “The identification of…drinking water users …is not sufficient” While the BCGSA is aware of a small number of private wells in the Basin, 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.

The BCGSA solicited information from private well owners during public meetings and through email and postal outreach but received little response.

Comment: “The identification of Interconnected Surface Water (ISW) is insufficient” The comment claims that brief periods of interconnection can be ecologically significant, and we have not proven that those do not occur.
• If connection is due to surface flow creating losing stream conditions, then the gaged inflows document when surface flow is available that might establish connection. However:
o Surface inflow from the Lee Lake Management Area in the Elsinore Subbasin is not affected by groundwater management in the Bedford-Coldwater Basin. o Any habitat value from those periods results from surface inflow, not groundwater discharge.
• Groundwater discharge is not flashy, the way stream flow is. Thus, although air photos represent only moments in time, they are more likely to detect groundwater discharge than surface flow events.
• Revisiting the Google Earth air photos including wet and dry seasons, we see groundwater emerging into a dry channel starting around the golf course in 2002 to 2004, 2012, and 2018. Throughflow (probably continuous from the Lee Lake Management Area in the Elsinore Subbasin) appeared to happen in 2005 to 2006, November 2009, and June 2012.

However:
o Perennial pools could easily be hidden from view by tree canopy. In the absence of perennial pools, the years with groundwater discharge-supported water in channel are probably too infrequent to support fish. Perennial pools can be important refugia for fish and other aquatic species. A channel survey for pools is needed. o The years with throughflow or groundwater discharge to a dry channel were years with significant wastewater discharges from Eastern Municipal Water District and/or Elsinore Valley Municipal Water District (verified by wastewater discharges before 2012 and gaged flow at Lee Lake after 2012). The possible open water in February 2018 upstream of Cajalco Road was the only event in a year without Lee Lake outflow.

The comment from the reviewers does not give examples of aquatic species and life history stages for which brief periods of groundwater-supported flow every few years are “essential”.

3 Board Members:

Paul Rodriguez, TVWD
Jacque Casillas, City of Corona
Phil Williams, EVMWD
We discussed the possible existence of aquatic species in the Bedford-Coldwater portion of the Temescal Wash with the Natural Resources Manager of the Riverside County Resource Conservation District and none were identified.

The conclusion “Therefore, potential ISWs are not being identified, described nor managed in the GSP” is an exaggeration. “Potential ISW” is a TNC term, not a Sustainable Groundwater Management Act (SGMA) term. There is extensive description and analysis of surface flow, riparian vegetation, and wetlands in the GSP. The GSP is managing groundwater dependent ecosystems (GDEs) by not allowing depth to water near Temescal Wash to drop more than 35 feet below the ground surface, which is much more restrictive than the water level minimum threshold.

The GSA recognizes that there is limited data on groundwater/surface water interaction and have identified this as a data gap. As noted in Section 8 of the GSP, a management action is described to monitor water levels in the vicinity of Temescal Wash, and a specific project is proposed to gather more information on potential groundwater/surface water interaction (including dedicated monitoring wells) along Temescal Wash.

Comment: “The identification of Groundwater Dependent Ecosystems is insufficient, due to a lack of comprehensive, systematic analysis of the basin’s GDWs.” • The comment incorrectly states that some GDEs were disregarded based on the proximity or presence of surface water. This is an incorrect representation of the GSP, which stated that at “wetland” polygons where depth to groundwater is clearly too large to have groundwater discharge, any “wetland” vegetation is likely seasonally supported by rainfall and local ponding of runoff.
• The comment states that the lack of correlation between groundwater levels and normalized difference vegetation index (NDVI) changes is not evidence that NDVI is unrelated to groundwater levels. This fails to explain how an uncorrelated variable can be a causal factor in NDVI.
• The last bullet of “Recommendations” requests a “complete inventory” of fauna and flora in the Basin. The GSP discusses thirteen animal species by name and the five most abundant woody riparian vegetation species by name. All of the species discussed in the MSHCP and USARHCP that historically or presently occur along Temescal Wash were reviewed for potential groundwater dependence. A longer list of species associated with riparian or wetland areas—particularly ones not a focus in the HCPs—would not change the analysis results.
• The last bullet of “Recommendations” incorrectly states that “The GSP mentions the Western Riverside County Multispecies Habitat Conservation Plan but provides few details.” In fact, Sections 4.9.4 and 4.9.4.1 each include a full paragraph describing the Multiple Species Habitat Conservation Plan (MSHCP) content that relates to Temescal Wash and the Basin. Also, Section 6.7.2.3 includes a full paragraph describing all species mentioned in the MSHCP whose habitat areas overlap the Basin. Furthermore, the comment neglected to note that the GSP also reviewed and discussed the Upper Santa Ana River Habitat

4 Board Members:

Paul Rodriguez, TVWD
Jacque Casillas, City of Corona
Phil Williams, EVMWD
Conservation Plan (HCP), the Temescal Creek Native Fish Restoration Project, interviews with Resource Conservation District (RCD) staff (two additional long paragraphs in (Section 6.7.2.3), and review of U.S. Fish and Wildlife Service (USFWS) critical habitat maps (Section 4.9.4.1). In summary, the comment grossly mischaracterizes the evaluation of plant and animal species as inadequate when in fact, the consideration of relevant species was ample and the analysis went far beyond simply listing species, which by itself is of little value.

B. Comment: “Public trust resources are not sufficiently considered.” The GSA encouraged stakeholder engagement throughout the GSP process. Outreach efforts included website updates, individual phone calls, email, and postal mail. Domestic well owners were invited to participate but none indicated concern about the development of the GSP. As noted above there are no tribes in the Basin, although tribes in the region were invited to public meetings and consulted for the monitoring well construction project. We are updating our outreach plan to include continuing engagement during GSP implementation.

C. Comment: “Impacts of Minimum Thresholds, Measurable Objectives and Undesirable Results on beneficial uses and users are not sufficiently analyzed.” DACs and drinking water users
Aside from the production wells of the BCGSA agencies, there is only one small community water system in the Basin, the Glen Ivy Hot Springs. The Glen Ivy well is regulated as a small community water system and is included in the sustainable management criteria. This well is also included as a monitoring well in the GSP and water levels and quality in the well will continue to be assessed as part of GSP implementation. As indicated in prior responses, there are no DACs or SDACs in the Basin and there are no known private domestic potable wells in the Basin. Project 2 (Section 8.7) will identify all active private wells in the Basin so that they can be included in sustainable management.

Distinct maps for perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and sulfate contamination are unavailable due to lack of available data and not required by SGMA.

Groundwater Dependent Ecosystems and Interconnected Surface Waters The comment letter characterizes the sustainable management criteria (SMC) for interconnected surface water as observed groundwater elevations from the 2014-2016 drought. This is incorrect.

The SMC is not defined in terms of historical groundwater elevations during 2014-2016. The minimum threshold (MT) for ISW is very clearly stated in Section 6.7.6:
“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.” It should be noted that this MT is much more restrictive than the MT for chronic declines in groundwater levels (see GSP Table 6.1).

5 Board Members:

Paul Rodriguez, TVWD
Jacque Casillas, City of Corona
Phil Williams, EVMWD

2. Comment: “Climate change is not sufficiently considered.” The comment states that “the GSP did not consider the 2070 extremely wet and extremely dry climate scenarios in the projected water budget.” The comment appears to be referring to two alternative sets of monthly climate multipliers provided in the files of climate change factors downloadable from the SGMA Data Portal. Those sets of factors are labeled Drier/Extreme-Warming (DEW) and Wetter/Moderate-Warming (WMW). There is no requirement to use anything but the expected factors.

In fact, the California Department of Water Resources (DWR) document “Guidance for Climate Change Data Use during Groundwater Sustainability Plan Development” does not even mention the alternative data sets. Rather, Section 4.5 of the guidance document states that uncertainty in climate change predictions is represented by inter-annual variability in the 50-year future simulations. It also states that the evaluation of sustainability will be based on the “central tendency” of the climate change factors, which is represented by the primary climate factor data set. The DEW and WMW data sets are for optional research purposes. Therefore, the climate change analysis in the GSP is adequate.

Our interpretation is that DWR is requesting two water budgets only (2030 and 2070) and that “uncertainty” is represented by the interannual variability represented by the 50 years of analysis. In other words, the climate change scenario is itself an expression of uncertainty relative to the future baseline scenario. Also, projects are evaluated on the “central tendency”, which is based on the expected climate change factors (the ones used in the GSP climate change analysis). There is no requirement for additional analysis of alternative climate change factor sets such as those identified in the comment.

3. Comment: “Data gaps are not sufficiently identified and the GSP does not have a plan to eliminate them.”
Data gaps in the monitoring network have been identified and projects and management actions to address those data gaps are included in the GSP. The existing Project 1 (Section 8.6) has been more clearly defined to include the siting and installation of shallow monitoring wells to eliminate the data gap for interconnected surface water, as described in response 4 below.

4. Comment: “Projects and Management Actions do not sufficiently consider potential impacts or benefits to beneficial uses and users.”
Please see previous responses regarding the identification of beneficial users and uses, including the project already in the GSP to locate all private (including domestic) wells (Project 2, Section 8.7).

Regarding interconnected surface water and GDEs, Project 1 (Section 8.6) was clarified and expanded to add more detail in a phased approach involving well siting and permitting review, followed by construction of shallow monitoring wells along Temescal Wash where possible. A survey for perennial pools along the entire length of Temescal Wash in the Basin will also be conducted. The new wells along Temescal Wash will greatly increase the knowledge of groundwater conditions near the wash, and appropriate reduction in pumping to protect GDEs, if required (Management Action 4).

6 Board Members:

Paul Rodriguez, TVWD
Jacque Casillas, City of Corona
Phil Williams, EVMWD
Once again, thank you for your detailed review of the Bedford-Coldwater GSP. We hope these responses to your comments are helpful.

Sincerely,
Victor Harris
BCGSA Administrator
Attachment: “Public Comment Letter for the Bedford-Coldwater Basin Draft GSP” dated September 6, 2021

Bedford-Coldwater GSP

TODD GROUNDWATER,
H&H Water Resources,
and Stantec

APPENDIX G
Bedford-Coldwater GSP Numerical
Groundwater Model Documentation Report

BEDFORD-COLDWATER
BASIN

GROUNDWATER

SUSTAINABILITY PLAN

GROUNDWATER MODEL

DOCUMENTATION REPORT
November 2021
2490 Mariner Square Loop, Suite 215
Alameda, CA 94501
510.747.6920
www.toddgroundwater.com

SIGNATURE PAGE
_____________________________
Katherine White, PE
Senior Hydrologist
Todd Groundwater, Alameda, CA
_____________________________
Michael P. Maley, PG, CHg, CEG, PE
Principal Hydrogeologist
Todd Groundwater, Alameda, CA

Bedford-Coldwater GSP
Groundwater Model Report i TODD GROUNDWATER
Table of Contents

1. Introduction............................................................................................................................. 1

1.1. Scope and Objective ........................................................................................................ 1

1.2. Summary of Previous Models.......................................................................................... 1

2. Basin Geology and Structure ................................................................................................... 2

2.1. Bedford Coldwater Basin ................................................................................................. 2

2.1.1. Physiography............................................................................................................ 2

2.1.2. Hydrology................................................................................................................. 2

2.1.3. Management Areas.................................................................................................. 2

2.2. Regional Geology ............................................................................................................. 3

2.2.1. Geologic Units.......................................................................................................... 3

2.2.2. Faults........................................................................................................................ 4

2.2.3. Pull-Apart Basin........................................................................................................ 4

2.2.4. Definable Basin Bottom ........................................................................................... 5

2.3. Groundwater conditions.................................................................................................. 5

2.3.1. Aquifer...................................................................................................................... 5

2.3.2. Recharge and Discharge Areas................................................................................. 5

2.3.3. Primary Groundwater Uses...................................................................................... 6

3. Rainfall-Runoff-Recharge Model ............................................................................................. 7

3.1. Approach.......................................................................................................................... 7

3.2. Land Use and Recharge Zones......................................................................................... 8

3.3. Rainfall ............................................................................................................................. 9

3.4. Interception ..................................................................................................................... 9

3.5. Runoff and Infiltration ..................................................................................................... 9

3.6. Root Zone Depth and Moisture Content ....................................................................... 10

3.7. Evapotranspiration......................................................................................................... 11

3.8. Irrigation......................................................................................................................... 11

3.9. Deep Percolation from Root Zone to Shallow Groundwater......................................... 12

3.10. Movement of Shallow Groundwater to Deep Recharge and Stream Base Flow........... 12

3.11. Evapotranspiration by Riparian Vegetation................................................................... 13

3.12. Groundwater Inflow....................................................................................................... 13

3.13. Calibration of Rainfall-Runoff-Recharge Model............................................................. 14

4. Numerical Groundwater Model Development...................................................................... 15

4.1. General Approach .......................................................................................................... 15

4.2. Model Setup................................................................................................................... 15

4.2.1. Model Code Selection............................................................................................ 15

4.2.2. Base Period ............................................................................................................ 16

4.2.3. Model Domain and Grid......................................................................................... 16

4.2.4. Model Layers.......................................................................................................... 17

4.2.5. Faults...................................................................................................................... 18

4.2.6. Aquifer Conditions................................................................................................. 18

4.3. Boundary Conditions...................................................................................................... 19

4.3.1. Surface Recharge ................................................................................................... 19

4.3.2. Streams .................................................................................................................. 19

4.3.3. Mountain Front Recharge...................................................................................... 20

4.3.4. Evapotranspiration................................................................................................. 21

4.3.5. Groundwater Pumping........................................................................................... 22

Bedford-Coldwater GSP
Groundwater Model Report ii TODD GROUNDWATER

4.3.6. Recycled Water Recharge Ponds ........................................................................... 22

4.3.7. Quarries.................................................................................................................. 22

4.3.8. Subsurface Flow with Adjacent Groundwater Basins............................................ 23

4.4. Aquifer Properties.......................................................................................................... 24

4.4.1. Aquifer Characteristics........................................................................................... 24

4.4.2. Zone Approach....................................................................................................... 25

4.4.3. Hydraulic Conductivity ........................................................................................... 25

4.4.4. Vertical Conductance............................................................................................. 25

4.4.5. Specific Yield and Specific Storage......................................................................... 26

4.5. Initial Condition.............................................................................................................. 26

5. Historical Model Results........................................................................................................ 27

5.1. Calibration Methodology ............................................................................................... 27

5.1.1. Approach................................................................................................................ 27

5.1.2. Calibration Methodology ....................................................................................... 27

5.1.3. Primary and Alternative Calibration ...................................................................... 28

5.2. Statistical Calibration ..................................................................................................... 29

5.2.1. Primary Calibration Results.................................................................................... 29

5.2.2. Alternative Calibration Results .............................................................................. 30

5.2.3. Comparison to Previous Model Calibration for Coldwater MA............................. 31

5.3. Groundwater Level Trends............................................................................................. 32

5.3.1. Bedford MA Hydrographs...................................................................................... 32

5.3.2. Coldwater MA Hydrographs................................................................................... 32

5.4. Evaluation Of Groundwater Flow .................................................................................. 34

5.5. Model-Based Hydrologic Budget ................................................................................... 35

6. Simulation of Future Conditions............................................................................................ 37

6.1. Baseline Scenario ........................................................................................................... 37

6.1.1. Baseline Assumptions............................................................................................ 37

6.1.2. Baseline Water Budget Results.............................................................................. 38

6.1.3. Baseline Groundwater Flow Evaluation................................................................. 39

6.2. Growth and Climate Change Scenario ........................................................................... 39

6.2.1. Growth and Climate Change Assumptions............................................................ 39

6.2.2. Growth and Climate Change Scenario Water Budget Results............................... 40

6.2.3. Future Growth and Climate Change Groundwater Map ....................................... 41

7. SGMA Requirements.............................................................................................................. 43

7.1. Model Data Gaps ........................................................................................................... 43

7.2. Model Accuracy.............................................................................................................. 44

7.3. Limitations to Calibration............................................................................................... 44

8. References Cited.................................................................................................................... 46 List of Tables (all tables follow text except where noted) Table 1 Bedford-Coldwater Basin Land Use (acres) (in Text) Table 2 Average Annual Groundwater Pumping
Table 3 Aquifer Properties
Table 4 Summary of Primary Calibration for The Bedford-Coldwater Model (in Text) Table 5 Statistical Calibration by Well

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Groundwater Model Report iii TODD GROUNDWATER
Table 6 Summary of Alternative Calibration for The Bedford-Coldwater Model (in Text) Table 7 Bedford-Coldwater GW Basin Water Balance (in acre-feet per year) - Historical Table 8 Bedford MA Water Balance (in acre-feet per year) - Historical Table 9 Coldwater MA Water Balance (in acre-feet per year) - Historical Table 10 Change in Groundwater in Storage (in acre-feet per year) - Historical Table 11 Bedford-Coldwater GW Basin Balance (in acre-feet per year) - Projected Future Baseline Table 12 Bedford MA Water Balance (in acre-feet per year) - Projected Future Baseline Table 13 Coldwater MA Water Balance (in acre-feet per year) - Projected Future Baseline Table 14 Change in Groundwater in Storage (in acre-feet per year) - Projected Future Baseline Table 15 Bedford-Coldwater GW Basin Water Balance (in acre-feet per year) - Projected Future Growth with Climate
Table 16 Bedford MA Water Balance (in acre-feet per year) - Projected Future Growth with Climate Change
Table 17 Coldwater MA Water Balance (in acre-feet per year) - Projected Future Growth with Climate Change
Table 18 Change in Groundwater in Storage (in acre-feet per year) - Projected Future Growth with Climate Change
List of Figures (all figures follow text)
Figure 1. Location and Topography of Bedford-Coldwater Basin Figure 2 Local Watersheds that Drain into the Bedford-Coldwater Basin Figure 3 Schematic Plan View Showing Faulting Associated with Pull-Apart Basins Figure 4 1990 and 2018 Land Use for Recharge Polygons
Figure 5 Average Annual Rainfall
Figure 6 Relationship of Rainfall to Infiltration
Figure 7 Rainfall to Runoff Calibration
Figure 8 Location of MODFLOW Model Domain
Figure 9 Location of Management Areas
Figure 10 Topographic Elevation of the Top of Model Layer 1 Figure 11 Bottom Elevation Distribution for Model Layer 1 Figure 12 Bottom Elevation Distribution for Model Layer 2 Figure 13 Bottom Elevation Distribution for Model Layer 3 Figure 14 Schematic NW-SE Cross Section to Illustrate Relative Model Layer Thicknesses Figure 15 Schematic NE-SW Cross Section to Illustrate Relative Model Layer Thicknesses Figure 16 Location of Faults Included in MODFLOW model
Figure 17 Location of Streams
Figure 18 Distribution of General Head Boundary Used for Mountain Front Recharge Figure 19 Distribution of Evapotranspiration (ET) Zones Figure 20 Location of Pumping Wells with Measured Pumping Rates Figure 21 Locations of Estimated Pumping for Historical Agriculture Figure 22 Annual Groundwater Pumping Volumes in Basin

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Figure 23 Location of Primary Quarry Areas and Wastewater Facilities Figure 24 Boundary Conditions Applied for Recharge Ponds, Quarries and Subsurface Flow Figure 25 Distribution of Aquifer Property Zones for Layers 1, 2 and 3 Figure 26 Initial Groundwater Conditions for Layer 2
Figure 27 Location of Monitoring Wells in MODFLOW Model in Bedford MA Figure 28 Location of Monitoring Wells in MODFLOW Model in Coldwater MA Figure 29 Scatter Plot Comparing Simulated to Measured Groundwater Levels Figure 30 Calibration Hydrographs Bedford MA North Temescal Wash Area Figure 31 Calibration Hydrographs Bedford MA North Temescal Wash Area Figure 32 Calibration Hydrographs Bedford MA Mid Temescal Wash Area Figure 33 Calibration Hydrographs Coldwater MA Coldwater Quarry Area Figure 34 Calibration Hydrographs Coldwater MA Mayhew Quarry Area Figure 35 Calibration Hydrographs Coldwater MA Other Quarry Area Figure 36 Calibration Hydrographs Coldwater MA North of Quarry Area Figure 37 Layer 1 Groundwater Elevations End of Simulation September 2018 Figure 38 Layer 1 Groundwater Elevations Near Highest Levels March 1995 Figure 39 Layer 1 Groundwater Elevations Near Lowest Levels October 2010 Figure 40 Simulated Change in Groundwater in Storage for Historical Simulation Figure 41 Simulated Groundwater Storage Change for Future Baseline Scenario Figure 42 Layer 1 Groundwater Elevations Future Baseline Scenario September 2068 Figure 43 2068 Land Use for Recharge Polygons for Future Growth Scenario Figure 44 Simulated Groundwater Storage Change for Growth-Climate Change Scenario Figure 45 Layer 1 Groundwater Elevations Future Growth Scenario September 2068

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1. INTRODUCTION
The groundwater model was developed to support the Groundwater Sustainability Plan (GSP) for the Bedford-Coldwater Subbasin of the Elsinore Groundwater Basin (DWR Groundwater Basin 8-004.02) and is prepared in accordance with Sustainable Groundwater Management Act (SGMA). For convenience, DWR Basin 8-004.02 will be referred to as the Bedford-Coldwater Subbasin (Basin) in this memo.

1.1. SCOPE AND OBJECTIVE
SGMA effectively requires that groundwater modeling be used to demonstrate that a GSP will achieve sustainable basin operation. Various numerical model that has been developed, periodically updated, and used for various scenarios since the 1990s. The objective of this model was to simulate the surface water and groundwater model for the entire Basin that updates key parameters the Basin boundary, discretization, geologic layering, aquifer parameter distribution. The assessment and final model focuses on applicability to SGMA GSP regulations including consistency with DWR Best Management Practices for surface water and groundwater modeling (DWR, 2016). This comprehensive groundwater model serves as a quantitative tool for computing Basin-wide and management area specific water budgets as required by the SGMA GSP regulations.

1.2. SUMMARY OF PREVIOUS MODELS
The Basin Model (Bedford-Coldwater Model) incorporates the hydrologic, geologic and groundwater data to develop a numerical groundwater model to evaluate local water budgets and assess sustainability criteria. An earlier groundwater model was developed for use on the Coldwater Basin Recharge Feasibility Study (MWH, 2004). The Bedford-Coldwater Model builds on earlier data from the 2004 MWH model, and expands the previous model in order to cover the rest of the Basin. This report documents the setup and calibration of the model, including the steps used to process to incorporate this data into the groundwater model.

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2. BASIN GEOLOGY AND STRUCTURE
The following summarizes the hydrogeologic conceptual model (HCM) and groundwater conditions from the GSP (see Sections 3 and 4). The HCM and groundwater conditions create a foundation of the technical aspects of the Basin’s hydrogeology necessary for model development. This section references figure and text in Sections 3 and 4 of the GSP.

2.1. BEDFORD COLDWATER BASIN
The Basin is a subbasin of the Elsinore Basin and covers approximately 11 square miles in western Riverside County (Figure 1). The Basin is located between the Santa Ana Mountains to the west and the Perris Plain on the east. The Basin is separated from the Temescal Subbasin to the northwest by a groundwater divide near Bedford Wash. A jurisdictional boundary separates the Basin with the Elsinore Valley Subbasin to the south. The Basin is thin in some areas, which impedes groundwater flow especially at the northern and southern boundaries.

2.1.1. Physiography
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 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 varies from below 12 inches to more than 26 inches over the Study Area. The longterm 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.

2.1.2. Hydrology
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 of the Basin. These waterways are ephemeral and are dry much of the year, flowing mainly during the winter. Water enters the basin as surface runoff and subsurface inflow from watersheds draining into the basin. The overall watershed tributary to the Basin was divided into 15 sub-watersheds for the purpose of simulating inflow to the model, as shown on Figure 2.

2.1.3. Management Areas
Two management areas have been designated for the Basin. These are:
• Bedford Management Area (Bedford MA) consists of the eastern areas of the Basin including Temescal Wash, and the Bedford area extends from the Elsinore Valley Subbasin to the south to the Temescal Subbasin to the north.
• Coldwater Management Area (Coldwater MA) consists of the western areas of the Basin and is more than 800 feet thick (Todd and AKM, 2008). The Coldwater Area does not share a boundary with either the Elsinore Valley or the Temescal Subbasins.

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The Glen Ivy fault separates the Bedford area from the Coldwater area, resulting in differing geology, water use, water quality, and sources of water between the two areas. The fault offsets the aquifer units in the Bedford MA from the units in the Coldwater MA by up to approximately 250 feet (Todd, 2019), with the total basin thickness greater on the west side of the fault (Coldwater MA) relative to the east side of the fault (Bedford MA). These differences serve as the basis for defining two management areas in the Basin for the purpose of facilitating implementation of the GSP. The Bedford and Coldwater MAs will be used in the water budget analysis for the surface water and groundwater modeling results.

The Bedford MA is the area east of the Glen Ivy fault and west of the Estelle Mountain area. Alluvial sediments are up to 500 feet thick in the Bedford MA (Todd and AKM, 2008). Land uses are primarily urban residential and commercial/industrial in the Bedford MA. Temescal Wash flows from the southeast to northwest along the full length of the Bedford MA along the northern boundary of the Basin.

The Coldwater MA is the area located in a deep basin area located west the Glen Ivy fault and east of the Santa Ana Mountains. Alluvial sediments are more than 800 feet thick in the Coldwater MA (Todd and AKM, 2008). The City of Corona and Elsinore Valley Municipal Water District established a production agreement in 2008 to ensure the sustainable use of groundwater in the Coldwater area (EVMWD, 2008). Glen Ivy Hot Springs is a community water system with one well in the Coldwater MA, it is estimated the water system serves 750 people.

2.2. REGIONAL GEOLOGY
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 northwestsoutheast trending fault zone including the Elsinore, Chino, and related faults. The Elsinore fault zone, including the Glen Ivy Fault, bound the Basin on the west and trend along the mountain front.

2.2.1. Geologic Units
The Bedford-Coldwater Basin is composed of alluvial fan, recent alluvial along Temescal Wash and older sedimentary rocks. 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. Alluvial deposits along Temescal Wash and local tributaries define the eastern boundary of the Basin. The alluvial fan deposits in the Coldwater area extend into the Bedford area and appear to have been disrupted by faulting (GSP, Section 3, Figure 3-5).

Both older and recent alluvial fans have been deposited along the mountain front on the western edge of the Basin. Although these deposits are relatively thick, the entire unit is heterogeneous. 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).

Alluvial thicknesses tend to increase toward the center of the basin away from the faults (MWH, 2004, Todd and AKM 2008).

Underlying much of the Basin is 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. In the northern Bedford area, a variety of

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Tertiary sedimentary units crop out including the Silverado (Paleocene), Vaqueros (Miocene), Topanga (Miocene), and Puente (Miocene) formations (GSP, Section 3, Figure 3-5).

These uplands surrounding the Basin are composed principally of granitic, volcanic and older sedimentary rocks of Jurassic and Cretaceous age. The Coldwater MA is surrounded by the metamorphic, volcanic and granitic basement rocks of the Santa Ana Mountains to the south and west.

Around the Bedford MA is an area of sedimentary units of Tertiary age that crop out along the mountain front generally lying east of the Glen Ivy Fault within the Elsinore Fault Zone. This zone of sedimentary units broadens to the north and contains numerous mapped formations of Cretaceous and Tertiary age.

2.2.2. Faults
The Glen Ivy Fault is associated with the right lateral strike-slip-dominated Elsinore Fault Zone that extends approximately 200 km from Baja California north to the Corona area. Bedrock faulting in the area largely controls depth to bedrock and the resultant alluvial thickness (MWH, 2004). The units in the Basin are truncated by the Glen Ivy fault that separates the Bedford area from the Coldwater area.

The location and effect of the Glen Ivy fault on the units of the Basin are shown on cross sections presented in GSP Section 3 (Figures 3-6 through 3-8). As shown on these cross sections, the Glen Ivy fault and related faults offset the units approximately by as much as 250 feet. This offset is inferred from well logs that extend to bedrock near the fault. Groundwater flow in the Basin is strongly affected by the Glen Ivy fault (Todd and AKM 2008, WEI 2015b) and the fault appears to be a nearly complete barrier to subsurface flow (MWH, 2004)

2.2.3. Pull-Apart Basin
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 MA is one of these pull-apart basins. Pull-apart 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 debris flow deposits which are extremely poorly sorted with a mixture of clay, sand, gravel and boulders as seen on the well logs at the lower depths. Since the movement on the faults is right-lateral, the oldest sediments will be located at the lower levels in the northern part of the Basin. As the pull-apart basin forms, progressively younger sediments will be deposited from north to south. Because of this type of deposition, the lower units of the pull-apart basin can be chaotic.

Pull-apart basins are topographic depressions that form at releasing bends or steps in basement strikeslip fault systems. Traditional plan view models of pull-apart basins usually show a rhombic to spindleshaped depression developed between two parallel master vertical strike-slip fault segments. The basin is bounded longitudinally by a transverse system of oblique-extensional faults, termed “basin sidewall faults” (Figure 3). Basins commonly display a length to width ratio of 3:1 (Wu et.al., 2012).

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. Based on the geology, the Glen Ivy fault limits deep groundwater flow, resulting in a limitation of the hydraulic connection between the Coldwater ad 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

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the Bedford area resulting in minor inflows from Bedford into the Coldwater area. This is shown in some recent groundwater level data (GSP Sections 3 and 4). 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 (MWH, 2004, Todd and AKM 2008), indicating more compartmentalization with depth.

2.2.4. 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 GSP, Section 3 (Figures 3-9). Aquifer thickness is greatest in the Coldwater portion of the Basin west of the Glen Ivy fault. Additional cross sections showing these relationships are provided in the GSP, Section 3 (Figures 3-6 through 3-8).

2.3. GROUNDWATER CONDITIONS
Understanding the groundwater conditions is important in development of the surface water and groundwater models. A summary of the discussion of the groundwater conditions and water balance based on the model results is provided in GSP Sections 4 and 5 is provided below.

2.3.1. Aquifer
The Basin is defined by the lateral extents of the alluvial material described above. This material is bounded by bedrock in the Santa Ana Mountain 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 over shallow bedrock in narrow valleys (Todd and AKM, 2008 and WEI, 2015b). 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 Basin is thin in some areas, which impedes groundwater flow. This is especially relevant at the northern and southern boundaries of the Basin. With the exception of the Glen Ivy fault described above, there are no other known aquifer characteristics impeding or impacting flow in the Basin.

The Basin aquifer is truncated by the Glen Ivy Fault that separates the Bedford area from the Coldwater area. The location and effect of the Glen Ivy Fault on the units of the Basin are shown on cross sections in GSP, Section 3 (Figures 3-6 through 3-8). As shown on these cross sections, the Glen Ivy Fault offsets the units by up to 250 feet. As noted above, these faults may sometimes impede groundwater flow, backing up groundwater west of the fault within the Coldwater MA and limiting flow into the Bedford MA (Todd 2019). However, there is insufficient 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.

2.3.2. Recharge and Discharge Areas
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. Most of the Basin recharge comes from the infiltration of runoff from precipitation in

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the Santa Ana Mountains west of the Basin and the Peninsular Ranges east of the Basin. Large amounts of runoff from the mountains flows 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 for recharge varies annually with changes in 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 exceeds the recharge capacity of 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). Discharge from wastewater treatment and subsurface inflow occur to a limited extent in the Basin. Recharge associated with wastewater is associated with discharge at the wastewater treatment facilities. Subsurface inflow occurs along the Basin boundaries. This is not considered to be a significant source of recharge to the Basin (Todd and AKM 2008).

Sand and gravel mining has been the predominant industrial land use in the southern half of the Coldwater MA, an activity that continues today. Localized sand and gravel operations are also located along Temescal Wash in the Bedford MA. In addition, berms along washes, diversions of surface water, and the presence of large gravel pits enhance groundwater recharge of runoff in Coldwater area (Todd and AKM, 2008).

Discharge from the Basin is almost entirely from groundwater pumping, evapotranspiration, and mining operations. There is some limited discharge across the northern Basin boundary with the Temescal Subbasin, but the thin alluvial material in this area limits the volume and timing of subsurface outflow along this boundary (Todd and AKM, 2008).

2.3.3. Primary Groundwater Uses
The primary groundwater uses in the Basin are municipal pumping, with limited private pumping for small water system, commercial, industrial and residential users. Groundwater use estimates are included in GSP Section 5 (Water Budget). Groundwater in the principal aquifer in the Bedford area is primarily used for non-potable municipal and irrigation water supply. 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. There has historically also been non-potable pumping in this area to support agricultural, recreational, small residential, and industrial water uses.

Gravel operations in the Coldwater MA extract water for industrial use to support sand and gravel mining. Their pumping amounts have ranged from about 100 AFY to 300 AFY, except for a period of increased production from 1975 through 1980 when production averaged about 450 AFY (Todd and AKM 2008).

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3. RAINFALL-RUNOFF-RECHARGE MODEL
A rainfall-runoff-recharge model developed by Todd Groundwater was used to prepare estimates of groundwater recharge from rainfall, irrigation, bedrock inflow, and pipe leaks. It also generated the estimates of groundwater use for agricultural irrigation and flows in ungauged streams tributary to or within the basin. Several commercially available software programs were used to prepare model input and evaluate model output, such as Microsoft Excel and ArcGIS. Finally, the rainfall-runoff-recharge model and several pre-processing utility programs were developed in the Fortran 90 programming language by Todd Groundwater.

3.1. APPROACH
The rainfall-runoff-recharge model is built around a soil moisture balance of the root zone, which is simulated continuously using daily time steps for the 29-year calibration period. Numerous variables are involved in the physical processes of rainfall, interception, runoff, infiltration, root zone soil moisture storage, evapotranspiration, irrigation, shallow groundwater storage, recharge of deeper regional aquifers from shallow groundwater, and lateral flow of shallow groundwater into streams. Accordingly, the groundwater basin and tributary watersheds were divided into small recharge zones over which the most influential variables were relatively homogeneous. The daily water balance was then simulated for each zone, and the results aggregated geographically to cells in the groundwater model grid and temporally to the model stress periods.

The rainfall-runoff-recharge model provides several benefits to the groundwater modeling effort:
• It represents the hydrological processes with governing equations that reflect the actual physical processes, at least in a simplified way. This allows sensitivity or suspected errors to be traced to specific assumptions and processes.
• It enforces the principle of conservation of mass on the recharge and stream flow values.

Beginning with rainfall, all water mass is accounted for as it moves through the hydrological system.
• It allows additional data sets to be included in model calibration. In tributary watersheds with gauged stream flow data, measured flows can be compared with simulated flows, which consist of the sum of direct runoff and shallow-groundwater seepage to streams. Simulated irrigation frequency can be compared with actual grower practices, and applied irrigation amounts can be compared with water delivery data recorded by the District. Simulated urban irrigation amounts can be compared with seasonal variations in measured urban water use, which are primarily related to urban irrigation.
• It provides estimates of stream flow in ungauged tributary streams, as well as runoff from valley floor areas within the active model domain.
• It provides estimates of inflow from bedrock and/or upland areas adjacent to the active model domain and constrains the amounts of inflow according to the water balance for each tributary watershed.
• It simulates the effects of runoff from impervious surfaces in urban areas, either to storm drainage systems or to adjacent pervious soils.
• It simulates changes in land use over the 29-year calibration period and the resulting changes in recharge and irrigation demand.

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• It combines and parses all of these flows—plus estimated recharge from leaky water and sewer pipes—into recharge values by model cell and stress period in the format required by MODFLOW.

The following sections describe the input data sets and the assumptions and governing equations used to simulate each hydrologic process included in the rainfall-runoff-recharge model.

3.2. LAND USE AND RECHARGE ZONES
Recharge zones were developed by intersecting and editing numerous maps in GIS. The starting point was a map of the Bedford-Coldwater Basin and the boundaries of all surrounding watersheds that flow into it. The Basin area was divided into the Bedford MA and Coldwater MA. The Basin and tributary watersheds were then divided into numerous polygons reflecting land use as of 1990 and changes in land use since then. Land use was delineated into 13 categories based on DWR land use maps for Riverside County from 1993 and 2000, a statewide crop map developed by LandIQ for DWR in 2014 and Google Earth historical aerial imagery available for 1990-2018. The primary change in land use has been urbanization of undeveloped (natural vegetation) areas. Polygons were delineated to represent the locations of changes in land use so that a single, fixed set of polygons could accurately represent the evolution of land use by changing the use type of a polygon beginning in the year that land use changed.

Additional divisions of polygons were made on the basis of soil texture, annual rainfall and watershed.

This resulted in a total of 224 polygons ranging in size from 2 to 4,529 acres. A map of the zones and their land uses in 1990 and 2018 is shown in Figure 4.

Land use in each zone was assigned to one of thirteen categories. The only agricultural crop in the Basin is citrus, which occupied about 1,900 acres in 1990 and was almost entirely converted to residential during the 1990s. Natural land cover categories are grassland, shrubs/trees, dense riparian, sparse riparian and open water. Developed land uses are residential, low-density residential, turf, commercial, industrial, quarry and vacant. The natural and developed land uses were mapped by inspection of Google Earth aerial photography. The categories are listed in Table 1 along with their total acreages in 1990, 2018 and 2068 (estimated) in the groundwater basin management areas and tributary watersheds.

Table 1. Bedford-Coldwater Basin Land Use (acres)

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Each land use category is further divided into irrigated, non-irrigated and impervious subareas. These are not explicitly mapped but are expressed as percentages of total zone area. Based on examination of aerial photographs and historical water use patterns, the percent impervious cover in urban land use areas was estimated to be 15 percent for low-density residential, 45 percent for residential, 70 percent for commercial and 80 percent for industrial. The corresponding percent irrigated area for those categories was estimated to be 14, 18, 10 and 0 percent, respectively.

3.3. RAINFALL
The distribution of average annual rainfall over the basin and tributary watersheds was obtained from PRISM climate modeling (http://www.prism.oregonstate.edu/ ). Each recharge zone was assigned an average annual rainfall value based on its location, as shown in Figure 5.

The surface hydrology model requires daily rainfall as one of two transient inputs. Daily rainfall for the Elsinore station was used for this purpose, with missing values supplied by correlation with rainfall at the Riverside Fire Station and Claremont-Pomona Stations, both of which also have long periods of record. Daily rainfall for each recharge zone was calculated as Elsinore daily rainfall multiplied by the ratio of zonal average-annual rainfall to Elsinore average-annual rainfall.

3.4. INTERCEPTION
Plant leaves intercept some of the rain that falls from the sky, and the amount is roughly proportional to the total leaf area of the vegetation canopy. The estimated interception on each day of rain ranged from zero for industrial, idle and vacant land uses, to 0.03 inch for turf and 0.06 inch for trees in full leaf.

These estimates were inferred from published results of interception studies (Viessman and others, 1977). For each day of the simulation, rainfall reaching the land surface (throughfall) is calculated as rainfall minus interception. Interception storage is assumed to completely evaporate each day and is not carried over from one day to the next.

3.5. RUNOFF AND INFILTRATION
Most throughfall infiltrates into the soil, but direct runoff occurs when net rainfall exceeds a certain threshold. The threshold at which runoff commences and the percent of additional rainfall that runs off are significantly influenced by a number of variables, including soil texture, soil compaction, leaf litter, ground slope, and antecedent moisture. These factors can be highly variable within a recharge zone, and data are not normally available for them. Also, the intercept and slope of the rainfall-runoff relationship depend on the time increment of analysis. Most analytical equations for infiltration and runoff apply to spatial scales of a few square meters over periods of minutes to hours (Viessman and others, 1977).

They are suitable for detailed analysis of individual storm events. The curve number approach to estimating runoff also applies to single, large storm events. It is not suitable for continuous simulation of runoff over the complete range of rainfall intensities (Van Mullen and others, 2002). The approach used in the rainfall-runoff-recharge model is similar but less complex than the approach used in popular watershed models such as HSPF (Bicknell and others, 1997).

In the rainfall-runoff-recharge model, daily infiltration is simulated as a three-segment linear function of throughfall, and throughfall in excess of infiltration is assumed to become runoff. The general shape of the relationship of daily infiltration to daily net rainfall is shown in Figure 6 (upper graph). Below a specified runoff threshold, all daily throughfall is assumed to infiltrate. Above that amount, a fixed percentage of throughfall is assumed to infiltrate, which is the slope of the second segment of the

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infiltration function. Finally, an upper limit is imposed that represents the maximum infiltration capacity of the soil. The runoff threshold, the percentage of excess net rainfall that infiltrates, and the maximum daily infiltration capacity were assumed to vary by land use and were among the variables adjusted for model calibration. The runoff threshold ranged from 0.2 inches per day (in/d) for unpaved areas in industrial and commercial zones to 1.0 in/d for turf and natural vegetation areas. The infiltration percentage for excess rainfall ranged from 60 percent in commercial and industrial areas to 94 percent in areas of natural vegetation. The maximum daily infiltration was set to 2.5 in/d in upland tributary areas and 4 in/d for zones overlying the Basin. These values were selected on the basis of calibration, although results were not very sensitive to this parameter.

The above parameter values are for soils that are relatively dry. Infiltration rates decrease as soils become more saturated. This phenomenon led to the development of the Antecedent Runoff Condition adjustment factor for rainfall-runoff equations (Rawls and others, 1993). However, application of the concept has been focused on individual storm events. For the purpose of the rainfall-runoff-recharge model, the adjustment provides a means of simulating empirical observations that a given amount of rainfall produces less runoff at the beginning of the rainy season when soils are relatively dry than at the end of the rainy season when soils are relatively wet. This effect is included in the recharge model as a multiplier that decreases the estimated infiltration as soil saturation increases. This multiplier is applied to the runoff threshold, the infiltration slope and the maximum infiltration rate. The multiplier decreases from 1.0 when the soil is dry to a user-selected value between 1.0 and 0.60 when the soil is fully saturated (lower graph in Figure 6). A low value has the effect of decreasing infiltration (and potential groundwater recharge) toward the end of the rainy season or in very wet years, and also to increase simulated peak runoff during large storm events. The multiplier under saturated conditions was assumed to be 0.75 for the Bedford-Coldwater rainfall-runoff-recharge model.

Runoff from impervious surfaces was assumed to equal 100 percent of rainfall. Runoff that flows into a storm drain system (known as “connected impervious runoff”) contributes to stream flow but not groundwater recharge. However, runoff from some impervious surfaces flows onto adjacent areas of pervious soils (“disconnected impervious runoff”). The surface hydrology model treats this type of runoff as if it were a large increment of additional rainfall where it flows over or ponds on the pervious soils. The excess water can quickly saturate the soil and initiate deep percolation. The model incorporates this process by means of a variable representing the fraction of impervious runoff that becomes deep percolation. Data and literature values are not available for this variable. It was estimated to be 20 percent in residential, commercial and industrial areas and 80 percent in low-density residential areas.

3.6. ROOT ZONE DEPTH AND MOISTURE CONTENT
The storage capacity of the root zone equals the product of the vegetation root depth and the available water capacity of the soil. The available water capacity for each recharge zone was a depth-weighted average for the dominant soil type, as reported in the soil survey (Natural Resources Conservation Service, 2015). Root depth is a complex variable. Except for cropland, vegetation cover typically consists of a mix of species with different root depths. At a very local scale, roots are deepest directly beneath a plant and shallower between plants. Root density and water extraction also typically decrease with depth within the root zone. To complicate matters, root depth is somewhat facultative for some plants, which means that roots will tend to grow deeper in soils with low available water capacity, such as sands. Finally, root depth in upland watershed areas can be restricted by shallow bedrock.

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The root depth selected for each recharge zone essentially represents an average of all these factors.

Simulated recharge and stream base flow are both quite sensitive to vegetation root depth, and values were adjusted during the joint calibration of the rainfall-runoff-recharge model and the groundwater flow model. Separate root depths were specified for irrigated and non-irrigated vegetation in each recharge zone. Root depths for turf and crops were required to be the same in all zones. In upland watersheds root depth can be affected by the depth to bedrock, which is often shallow. Outflow from individual tributaries flowing into the basin is not gaged, and uniform rooting depths for grass and shrubs/trees were used throughout all of the watersheds.

3.7. EVAPOTRANSPIRATION
Evapotranspiration is affected by meteorologic conditions, plant type, plant maturity, and soil moisture availability. All of these factors are included in the rainfall-runoff-recharge model. The evaporative demand created by meteorological conditions is represented by reference evapotranspiration (ETo).

Numerous equations have been developed over the years relating ETo to solar radiation, air temperature, relative humidity and wind speed. For the purposes of this study, daily values of ETo were obtained from a microclimate station in Temecula (about 20 miles south of the Basin) that is part of the California Irrigation Management Information System (CIMIS) network.

Vegetation factors are lumped into multipliers called crop coefficients. Reference ET is the amount of water evapotranspired from a broad expanse of turf mowed to a height of 4-6 inches with ample irrigation. ETo is multiplied by a crop coefficient to obtain the actual ET of a different crop or vegetation type at a particular stage in its growth and development. Although primarily used for agricultural crops, crop coefficients can also be applied to urban landscape plants and natural vegetation. The only agricultural crop in the Basin is citrus trees, which have a crop coefficient that ranges from 0.5 in winter to 0.91 in mid-summer (U.N. Food and Agriculture Organization, 2006). Irrigated landscaping was assumed to consist primarily of turf, for which a crop coefficient of 0.8 was used in all months (Snyder and others, 2007). Non-irrigated natural grassland consists of annual grasses that go dormant in summer once soil moisture has been depleted. A crop coefficient of 1.0 was assigned in all months, but actual ET decreases to zero as the grasses lower soil moisture to the wilting point in summer. Natural shrubs/trees were assigned a crop coefficient of 0.8 year-round. Those perennial species have deeper roots and do not tend to fully deplete root zone soil moisture during a single dry season (Blaney and others, 1963).

Many riparian phreatophytes are deciduous, and a crop coefficient of 0.75 was assigned for winter months to reflect a reduced leaf area index. Their tall stature and linear distribution within an arid landscape raises the crop coefficient in summer months, and a coefficient of 1.10 was assigned to reflect those factors.

3.8. IRRIGATION
Evapotranspiration gradually depletes soil moisture, and for irrigated areas the rainfall-runoff-recharge model triggers an irrigation event whenever soil moisture falls below a specified threshold. The amount of applied irrigation water is equal to the volume required to refill soil moisture storage to field capacity, divided by the assumed irrigation efficiency. An irrigation threshold equal to 70 percent of maximum soil moisture storage was used for citrus, and a threshold of 0.8 was used for urban landscaping. This variable primarily affects the frequency of irrigation; a higher threshold results in more frequent irrigation but approximately the same total amount of water applied annually. Ten percent of water applied to citrus was assumed to percolate past the root zone, and 15 percent was assumed for urban irrigation. This reflects nonuniformity of applied water, such as uneven overlap of sprinkler spray areas.

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There are additional sources of irrigation inefficiency, such as evaporation of sprinkler spray mist and sprinkler overspray or runoff onto impervious surfaces in urban areas. Thus, total irrigation efficiency is less than 90 percent for citrus and 85 percent for urban landscaping. Total efficiency was used to estimate applied water, but only the deep percolation component was used to estimate deep percolation. Urban irrigation in the Basin is supplied by municipal water purveyors, and irrigation use is included in their metered deliveries. The rainfall-runoff-recharge model was only used to estimate groundwater pumping for citrus irrigation.

Because irrigation is assumed to completely refill soil moisture storage and is less than 100 percent efficient, simulated soil moisture exceeds capacity immediately following an irrigation event. The excess is assumed to become deep percolation beneath the root zone.

3.9. DEEP PERCOLATION FROM ROOT ZONE TO SHALLOW GROUNDWATER The surface hydrology model updates soil moisture storage each day to reflect inflows and outflows.

Rainfall infiltration and applied irrigation water are added to the ending storage of the previous day, and ET is subtracted. If the resulting soil moisture storage exceeds the root zone storage capacity, all of the excess is assumed to percolate down from the root zone to shallow groundwater on that day. In modeling parlance, this is known as a “bathtub model”; vertical unsaturated flow and preferential flow through cracks and root tubes in the soil are not considered.

3.10. MOVEMENT OF SHALLOW GROUNDWATER TO DEEP RECHARGE AND

STREAM BASE FLOW
A shallow groundwater storage component may not be part of all groundwater systems, but its presence is sometimes indicated by groundwater hydrographs and stream base flow. In upland watersheds, for example, the shallow groundwater reservoir is what supplies base flow to streams.

Without it, simulated stream flow consists of large flows occurring only on rainy days. Physically, it represents the overall permeability and storage capacity of deep soil horizons and bedrock fractures beneath hillsides bordering a gaining stream. It allows the integration of shallow and deep, fast and slow flow paths between the point of rainfall infiltration and the stream. In valley floor areas with flat terrain and deep deposits of unconsolidated basin fill, the presence of a shallow groundwater system is sometimes evident in a lack of response of deep well hydrographs to rainfall recharge events or even wet versus dry years. The shallow zone in that case attenuates the pulses of recharge percolating beneath the root zone into a relatively steady recharge flux, and there may be little outflow to streams.

In the surface hydrology model, the only inflow to shallow groundwater storage is deep percolation from the root zone. There are two outflows: laterally to a nearby creek and downward to the regional groundwater flow system. Outflow to streams is specified as a certain percentage of current groundwater storage, which results in a first-order logarithmic recession of stream base flow, consistent with gaged stream flows. Outflow to the regional groundwater system is simulated as a constant downward flux. This is consistent with flow across confining layers in which the vertical head gradient is near unity. Both outflows are calculated and subtracted from shallow groundwater storage each day.

They continue until the storage has been exhausted, resuming whenever a new influx of deep percolation from the root zone arrives. There is no assumed maximum capacity of shallow groundwater storage.

The two parameters defining shallow groundwater flow are the recession constant for flow to streams and the constant downward flow rate for deep recharge. Both of these are obtained by calibration. The

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recession constant can generally be calibrated by matching simulated to measured stream base flow in gaged watersheds. The deep recharge rate can be used to adjust the long-term partitioning of shallow groundwater mass into base flow versus recharge.

The shallow groundwater component of the surface hydrology model is simple but adequate to capture the fundamental behaviors of logarithmic stream base flow recession and attenuated deep recharge.

Other watershed models invoke more complex systems of storage and flow to simulate these processes.

For example, the Precipitation and Runoff Modeling System (PRMS) developed by the U.S. Geological Survey includes a total of seven storage components between the point where a raindrop reaches the ground and the stream into which it ultimately flows (Markstrom and others, 2015). This larger number of components and parameters enables relatively detailed matching of observed stream flow hydrographs but is unnecessarily complex for the purposes of groundwater modeling.

3.11. EVAPOTRANSPIRATION BY RIPARIAN VEGETATION
In locations where the water table is shallow, some plants (phreatophytes) can extract water directly from the water table to meet evaporative demand. The rainfall-runoff-recharge model was used to estimate the amount that would be drawn from the water table if a shallow water table were present.

The potential use of groundwater by phreatophytes was assumed to equal the ET demand of the vegetation minus the amount that could be supplied by soil moisture. In practice, this was accomplished by temporarily simulating the vegetation as if it were irrigated using the rainfall-runoff-recharge model, then using the simulated irrigation rates as the maximum rate of withdrawal by roots from the water table. This rate of groundwater use is thought to decrease with increasing depth to the water table because fewer shrub and tree roots are able to reach the water table and the energetics of withdrawing the water become less favorable. The use of groundwater decreases from the maximum rate when the water table is at the land surface to zero when the water table is 15 feet or more below the ground surface. These calculations are applied at model cells where aerial photographs indicate the presence of dense, lush riparian vegetation, which is a sign of phreatophytic water use. These calculations were also made using the MODFLOW evapotranspiration (EVT) module.

3.12. GROUNDWATER INFLOW
Groundwater inflow into the basin from adjacent uplands—also called mountain front recharge—is difficult to estimate. If the basin is bounded by igneous or metamorphic rocks with very limited groundwater flow through fractures, it can be reasonable to assume that inflow from bedrock is negligibly small. If the bedrock is fractured, the total amount of inflow across the long “no-flow” boundaries on the east and west sides of the Basin can be cumulatively significant. Subsurface inflow across those boundaries was estimated using the rainfall-runoff-model results for the tributary watersheds. By this method, the estimates must be consistent with conservation of mass in the watersheds; that is, with the estimates of rainfall, ET, and surface outflow. The resulting estimates are still highly uncertain, however, because groundwater outflow from the watersheds—and surface outflow, too, for that matter—are both small compared to the two largest flows in the watershed water balances: rainfall and evapotranspiration. Thus, a small error in the estimate of either of those flows can result in a large error in groundwater outflow.

Ultimately, groundwater flows produced by the rainfall-runoff-recharge model were calibrated based on their effects on simulated groundwater levels at nearby wells within the basin and on the simulated amount of stream base flow exiting the watersheds. The initial groundwater inflow estimates were generally too high. The estimates were lowered primarily by increasing the estimated root depth of

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natural vegetation in the watersheds, which is highly uncertain due to the effects of shallow bedrock on rooting depth.

Groundwater inflow from tributary watersheds was smoothed over time to reflect attenuation of recharge pulses that occur during wet months and wet years as they gradually flow through long, relatively slow flow pathways. Smoothing was accomplished by a moving average of simulated groundwater recharge in the tributary areas over the preceding 2-10 years. This range represents local variability that was indicated by rates of recession in stream base flow and groundwater levels near the basin boundary during prolonged droughts. The final estimate of average annual groundwater inflow during the calibration period was 5,400-7,200 AFY under normal climatic conditions.

3.13. CALIBRATION OF RAINFALL-RUNOFF-RECHARGE MODEL
Parameters in the rainfall-runoff-recharge model were jointly calibrated with the groundwater model.

The total amount of dispersed recharge and annual variations in recharge influence simulated groundwater levels, and parameters in the rainfall-runoff-recharge model were adjusted to improve the fit between measured and simulated groundwater hydrographs. The rainfall-runoff-recharge model was also calibrated based on a comparison of measured and simulated daily stream flow at two gage locations: Coldwater Canyon Creek and Temescal Wash at the Lee Lake dam. Coldwater Canyon Creek flows into the adjacent Bedford-Coldwater Basin and is the only gaged stream draining the eastern slopes of the Santa Ana Mountains. Characteristics and model parameters for that watershed were assumed to also apply to similar watersheds along the western edge of the Basin. Unfortunately, the gage began operation in 2019, which is after the 1990-2018 model simulation period. Nevertheless, the general pattern of flow peaks and base flow recession simulated in prior years was similar to the gaged pattern in 2019-2020, as shown in Figure 7.

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4. NUMERICAL GROUNDWATER MODEL DEVELOPMENT
The numerical model incorporated the hydrogeological data from the basin and hydrologic model and is capable of simulating historical and future conditions. The following section describes the development of each of the components in the MODFLOW model.

4.1. GENERAL APPROACH
The Bedford-Coldwater Model is a numerical groundwater model, which is a mathematical description of the hydrogeological conceptual model (Bear and Verruijt, 1987). The advantage of a numerical model is that, once in a mathematical format, the model quantitatively combines data on basin geometry, aquifer properties, recharge, and discharge to simulate changes in groundwater elevations and calculate the water balance over time.

The Bedford-Coldwater Model is setup to represent the physical features that influence groundwater flow including the geology, hydrology and climate. Each of these features is mapped onto a model grid that represents the vertical and horizontal distribution of parameters over the Basin based on the hydrogeological conceptual model. The parameters can also be varied through time over a defined base period to represent seasonal variations in precipitation, streamflow and groundwater pumping. A more detailed discussion of how each of these parameters was developed and entered into the BedfordColdwater Model is summarized below. • Model Setup - representation of the physical groundwater basin • Boundary Conditions – representation of the inflows and outflows from outside of the model • Aquifer Properties – representation of the flow characteristics of the aquifer • Initial Conditions – representation of groundwater conditions prior to the model period The model development was focused on the HCM with emphasis on defining boundary conditions and flow paths. Aquifer parameters were assigned on a subregional basis within each MA and varied by model layer to represent reasonable aquifer properties for the geologic unit being simulated.

4.2. MODEL SETUP
The model also incorporates spatial distribution of the physical features of the Basin and the temporal distribution of time-varying parameters such as precipitation and recharge. The following describes the basic components required to construct a numerical model.

4.2.1. Model Code Selection
The model setup utilizes the MODFLOW modeling code developed by the United States Geological Survey (USGS). The Bedford-Coldwater Model uses MODFLOW-NWT (Niswonger et al, 2011), which is a standalone version of MODFLOW-2005 (Harbaugh, 2005) that includes an advanced mathematical solver that provides a more robust solution to complex conditions such as rewetting of dry model cells, unconfined conditions and groundwater-surface water interactions. These features improve the ability of the Model to evaluate complex groundwater-surface water interactions, potential conjunctive use, and other projects to increase future groundwater levels in the Basin.

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4.2.2. Base Period
The update Bedford-Coldwater Model is setup using water years that run from October through to the following September to capture the cause and effect relationship on groundwater levels of wintertime rain and subsequent summertime groundwater pumping. The model simulates the 29-year base period from October 1989 through September 2018 to represent Water Years (WY) 1990 through 2018. This retains the starting date of prior models, which coincides with the beginning of some key data sets and also the beginning of the period of rapid land use conversion from agricultural to urban. The ending year is the most recent year for which all necessary model input data were available. The 29-year simulation period is desirable for model calibration purposes because it includes a wide range of hydrologic and water use conditions, including wet periods, droughts, changes in groundwater pumping and implementation of lake management measures.

To simulate this base period, the model is subdivided into time intervals termed stress periods. For each water year, monthly stress periods were defined to provide the ability of the model to evaluate temporal at a monthly scale. For the base period, a total of 348 stress periods were defined. Timedependent parameters, such as groundwater pumping or precipitation recharge, are assigned to for each stress period.

Conditions during the stress period are constant, but parameters can be varied from stress period to stress period. A stress period can be subdivided into shorter time periods, or timesteps, to allow for more temporal resolution within each stress period to help with model convergence. For the BedfordColdwater Model, each stress period was simulated using three (3) timesteps. MODFLOW calculates the groundwater elevations and water balance for each time step. The model results provide the groundwater elevations for the final timestep of each stress period, and the summation of the water balance changes for all timesteps for each stress period.

4.2.3. Model Domain and Grid
MODFLOW requires the application of a rectangular grid that encompasses the entire area, or domain, that will be modeled. The model grid forms the mathematical framework for the model. Each grid cell has to be populated with aquifer properties. Physical features such as streams and wells are mapped onto the model grid. Using this information, the MODFLOW model calculates a groundwater elevation at each model grid cell for each timestep. The density of model grid cells is what defines the resolution of the model in resolving drawdown and other hydrologic effects.

The Basin covers about 11 square miles of the Santa Ana River Watershed that underlies the Elsinore Valley in western Riverside County. The extent of the model domain for the Bedford-Coldwater Model is shown on Figure 8. The Basin has two management areas that are defined within the model domain for water budget zone budgets (Figure 9). These include:
• Bedford Management Area (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 Bedford MA connects to the Elsinore Subbasin in the south and the Temescal Basin at the north end of the Basin.,
• Coldwater Management Area (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 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.

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The Bedford-Coldwater Model consists of 250 rows, 365 columns and 3 layers. The rows and columns have a uniform spacing of 100 feet. Each 100-foot square represents a model cell. MODFLOW calculates one groundwater level for the center point of each grid cell for each timestep. The total number of grid cells in the Bedford-Coldwater Model is 273,750 cells, of which 87,882 are active cells where MODFLOW calculates a groundwater levels. The active areas represent the area within the groundwater basin where groundwater elevations are simulated.

Areas outside of the Basin are represented as no-flow cells where MODFLOW does not perform calculations. The high percentage of no-flow cells in the model grid is due to both the elongate shape of the Basin, the inclusion of narrow watersheds off of the main Basin, and because the distribution of active cells varies from layer to layer. The bottom of the lowest model layer is a no-flow boundary condition, representing the older bedrock formations that are assumed to be relatively impermeable.

4.2.4. Model Layers
The model layers represent the geologic the geologic units that compose the Principal Aquifer of the Basin based on the geology and HCM presented in summarized in Section 2. Model layers provide vertical resolution for the model to simulate variations in groundwater elevation, aquifer stresses, and water quality with depth. The model layers are based on an evaluation of the following data sets:
• Surficial geology,
• Faulting,
• Lithologic borehole logs.
• Well construction logs, and
• Previously completed local hydrogeologic conceptualizations and cross sections.

This information was collected and translated into a unified GIS compatible database structure for cross section construction and geographic evaluation. This approach allows any hydrostratigraphic structures relevant to groundwater flow in the Basin to be easily translated from GIS for use in other formats.

For the Bedford-Coldwater Model, three model layers were defined to simulate hydrogeologic character of the primary water-bearing sediments within the groundwater basin. The model layers are numbered from 1 through 3 from top to bottom. The top of Model Layer 1 represents the topography that is based on topographic elevation points every 10 meters were extracted from the National Elevation Dataset (http://ned.usgs.gov) throughout the model domain Figure 10.

The model layers represent the geologic units within each of the hydrologic areas. Figures 11 through 13 show the areal extent and thickness of each of the model layers over the entire model domain.

Figures 14 and 15 show cross sections of the model grid along row 127 and column 230, respectively, to illustrate the shapes and relative thicknesses of the layers. The following provides a summary of the geologic units represented by each model layer in accordance with the HCM for the three hydrologic areas.

In the Bedford MA, three model layers were defined that represent the following geologic units:
• Model Layer 1 – Temescal Wash alluvium and shallow soils • Model Layer 2 – Tertiary sedimentary units primarily the Bedford Canyon Formation • Model Layer 3 - Weathered bedrock
The alluvium along Temescal Wash is the primary water supply unit in the Bedford MA (Todd and AKM 2008) where the larger wells are completed. The alluvial deposits are a mix of interlayered gravels, sands, silts, and clays resulting from alluvial fan and fluvial processes. Model Layer 1 ranges up to 80 feet

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thick along the Temescal Wash. Alluvial aquifer materials are present in other parts of this hydrologic area, but their extent and production capacity are uncertain. In these areas, Model Layer 1 represents a relatively thin layer, with a minimum thickness of five feet, that overlies the Bedford Canyon Formation that is rarely saturated.

Model Layer 2 represent the Bedford Canyon Formation that is composed of alternating slate and finegrained sandstone, underlies alluvial deposits in this hydrologic area and is generally less than 200 feet deep (Todd and AKM 2008). It is reported to have limited groundwater production potential (Todd and AKM 2008). The bottom of Model Layer 2 is defined based on depth to bedrock data in the Bedford MA that ranges from 25 feet to approximately 500 feet (Todd and AKM 2008). Model Layer 3 represents the weathered and fractured bedrock formations underlying Model Layer 2. These basement rocks have limited produce significant groundwater except in fractures (Todd and AKM 2008).

In the Coldwater MA for the areas outside of the deep basin area that are upgradient of the Wildomar and Glen Ivy Faults, three model layers were defined that represent the following geologic units:
• Model Layer 1 – Coldwater Basin alluvial fill sediments. • Model Layer 2 - Older Alluvial deposits
• Model Layer 3 - Weathered Bedrock
The alluvium (both young and old) that fills the deep basin in the Coldwater Basin, represented by Model Layers 1 and 2, forms the majority of the Basin aquifer. These alluvial deposits may be more than 800 feet thick locally and are composed of interfingered gravels, sands, silts, and clays (MWH 2004, Todd and AKM 2008). Groundwater is generally unconfined in these aquifer units.

Model Layer 3 represents the weathered and fractured bedrock formations underlying Model Layer 2.

Domestic wells competed along the margins and along the narrow canyons that extend from the main part of the groundwater basin are completed in weathered bedrock. Model Layer 3 is represented by a uniform thickness of 75 feet in the weathered bedrock based on well logs of domestic wells along the basin margin.

4.2.5. Faults
The Basin is dominated by the Glen Ivy Fault zone that forms a partial barriers to groundwater flow in the between the Bedford and Coldwater MAs based on water level differences and on analysis of sources of groundwater recharge across the fault (MWH 2004, Todd and AKM 2008). The location of the faults applied for the Bedford-Coldwater Model are shown on Figure 16. For the Bedford-Coldwater Model, all faults extended across Model Layers 1 through 3.

The faults were simulated using the Horizontal Flow Boundary (HFB) Package in MODFLOW that allows by defining a conductance parameter to be placed between adjacent model cells that can act to limit groundwater flow. All of the faults were simulated as a 10-foot wide zone. The lowest fault hydraulic conductivities were applied for the faults bordering the Back Basin where the hydraulic conductivity ranged from 0.0001 to 0.00001 ft/d. The fault hydraulic conductivities were based on an initial estimate that was refined during model calibration.

4.2.6. Aquifer Conditions
Groundwater conditions for each model layer can be defined as unconfined, fully-confined, or convertible between confined and unconfined based on the relation of the simulated groundwater level to the top of the model layer. Unconfined conditions exist when groundwater levels are below the top

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of the physical aquifer layer whereas confined conditions exist when groundwater levels are above the top of the physical aquifer layer. For the Bedford-Coldwater Model, Model Layer 1 is defined as unconfined. Model Layers 2 and 3 are defined as convertible between confined and unconfined conditions.

Because of the historical changes in groundwater levels, areas within the Basin can be temporarily unsaturated. Prior MODFLOW versions set a dewatered cell to a no-flow condition for the rest of the simulation if the cell is dewatered. An important advantage of using MODFLOW-NWT compared to previous MODFLOW versions is that groundwater heads will be calculated for dry cells, whereas standard MODFLOW excludes these calculations (Niswonger et. al., 2011). This resaturation capability of MODFLOW-NWT was utilized for the Bedford-Coldwater Model.

In MODFLOW-NWT, cells can be reset to active using the rewetting option without setting a dewatered cell to no flow condition. MODFLOW-NWT will calculate a head in a dry cell while not allowing water to flow out of a dry cell that provides a continuous solution for groundwater flow. Inflow to a dry cell, either from adjacent cells, overlying cells, or an external source simulated by one of the stress packages, automatically flows downward to an underlying cell if there are deeper layers. A cell with head below the cell bottom has no water in storage, so changes in storage also are zero for these cells. The model accounts for this situation by setting the storage coefficient for a dry cell to zero. This allows for the continuous solution of head not to affect the overall water balance results (Niswonger et. al., 2011).

Because groundwater heads are calculated for dry cells using this approach, it is necessary for the model user to interpret the head in a cell relative to the cell bottom. If the head in a cell is at or below the cellbottom altitude, then the water table is not contained within this cell (Niswonger et. al., 2011).

4.3. BOUNDARY CONDITIONS
Model boundary conditions represent the hydrologic budget by simulating where groundwater enters and exits the basin. Boundary condition data must be entered for each stress period at each model grid cell where a boundary condition is defined in the model. MODFLOW NWT provides a number of boundary condition options to numerically represent the different physical processes included in the hydrologic budget. The physical distribution and volumes of groundwater inflow and outflow for each budget component needs to be accounted for geographically within the model domain. A discussion of each boundary condition of the groundwater budget is provided below.

4.3.1. Surface Recharge
The surface recharge includes the contributions from precipitation and return flows within the BedfordColdwater Model. The surface recharge is applied using zones that are defined by the geology and land use. Surface recharge is applied using the MODFLOW recharge package and using the methods outlined below. This summary discusses implementation of surface recharge into the Bedford-Coldwater Model.

4.3.2. Streams
The groundwater model dynamically simulates groundwater recharge from stream percolation and groundwater discharge into streams. Percolation from streams is a function of stream flow and—where the water table is equal to or higher than the stream bed elevation—the difference in water level between the creek and water table.

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The MODFLOW stream flow routing (SFR2) package is used to simulate these processes. Each stream in the basin is simulated as a sequence of reaches, each of which is a model grid cell along the alignment of the channel. Flow is specified at the upstream end of each stream segment and routed down the reaches, with flow to or from the aquifer calculated on the basis of wetted channel area, channel bed hydraulic conductivity and the difference in elevation between the stream surface and the simulated groundwater level at that reach. By this means conservation of mass is applied concurrently to the stream and the aquifer. Streams can dry up completely as they cross the basin; and conversely, groundwater discharge can create stream flow in a segment that is dry farther upstream. The stream flow routing module allows for a network of channel segments, with multiple inflows or diversions at the start of each segment.

The Bedford-Coldwater Model includes a network of 43 stream segments containing a total of 1,363 stream reaches (Figure 17). Twenty-two segments are used to simulate eleven streams that drain watersheds in the Santa Ana Mountains along the west side of the Basin. Streams that flow across the Coldwater MA onto the Bedford MA where they connect up with Temescal Wash are divided into multiple segments to represent varying underlying geologic conditions. Temescal Wash is composed of thirteen segments that represent reaches along Temescal Wash. Five segments represent the short sections of five streams that drain watersheds in the Estelle Mountain and other upland areas east of Temescal Wash. Three segments represent internal drainage within the Basin the receive valley floor runoff in the northern Bedford MA.

In general, most stream reaches are more than 20 feet above the water table and are not hydraulically coupled to groundwater. Percolation from those reaches is independent of groundwater levels and not affected by pumping. Reaches where groundwater appears to be hydraulically coupled to surface water primarily include most of the length of Temescal Wash, and the lower ends of some larger tributaries as they approach the wash. All streams in the Coldwater MA are detached from the groundwater except for limited areas in the small canyons along the western basin margin.

Stream bed permeability was estimated by model calibration. Calibrated values ranged from 0.1 to

1.0 feet per day (ft/d). The relationships of stream width and depth to stream flow were divided into two categories. For small tributary streams, the relationships were patterned after measured data at the Coldwater Canyon gage. Inflows for Temescal Wash are coordinated with output from the Elsinore Valley numerical model and the USGS gauge located downstream of Lee Lake just south of the basin boundary with the Basin.

To develop estimates of surface and subsurface inflows from these tributary areas to the groundwater basin, a rainfall-runoff-recharge model is used to simulate the entire watershed tributary to the Basin.

This model simulates all near-surface hydrologic processes, including rainfall, runoff, infiltration, evapotranspiration, effects of impervious areas and irrigation, soil moisture storage and percolation to stream base flow and deep groundwater recharge. The calculated runoff is included in the SFR2 Package.

4.3.3. Mountain Front Recharge
Groundwater inflow into the basin from adjacent uplands—also called mountain front recharge—were calculated by the rainfall-runoff-recharge model (see Section 3). Mountain front recharge represents subsurface inflow of groundwater from the low-permeability rocks adjacent from the surrounding watershed to the groundwater Basin. the MODFLOW General Head Boundary (GHB) package was applied along the basin margin in Model Layer 3 which represents the weathered bedrock. The distribution of the GHB cells is shown on Figure 18.

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The GHB package is a head dependent boundary condition; therefore, the amount of groundwater flowing into or out of this boundary was influenced by the relative hydraulic gradient between the basin and the boundary condition. To have the GHB package input the bedrock inflows determined by the rainfall-runoff-recharge model (see Section 3), the GHB was set up to act as a rate limited flux boundary.

To do this, the reference head was a considerable distance away (one mile) from the recharge location, so it is well above the groundwater levels in the model. The conductance and elevation terms for the GHB package were back-calculated to get the appropriate flux. By setting the head at distance, the variability due to the changing heads in the groundwater model produces a variation of 1 to 2 percent in the GHB flux compared to the rainfall-runoff-recharge model values. The advantage of this approach is that the bedrock inflow can more easily be distributed to a large number of cells along the basin margin to maintain simulation stability. In addition, this approach allows the Bedford-Coldwater Model to simulate a consistent groundwater gradient flowing away from the margins to be consistent with the HCM.

4.3.4. Evapotranspiration
Evapotranspiration (ET) represents groundwater outflow from evaporation to the atmosphere and uptake by plants from the saturated zone. This is distinct from ET associated with soil moisture before it reaches the groundwater aquifer that is sustained by the total available precipitation not accounted for by runoff or recharge (see Section 3).

The MODFLOW Evapotranspiration (EVT) package is used simulate ET directly from the groundwater aquifer. ET is defined over the entire model domain; however, ET only occurs in areas of shallow groundwater. In the Basin, this is generally limited to riparian areas adjacent to streams. ET includes uptake from both phreatophytes (plants that require groundwater) and mesophytes (plants that can utilize groundwater) either directly from the saturated zone or from the overlying capillary fringe (Meinzer, 1927; Robinson, 1958; and Lewis and Burgy, 1964). ET from the capillary fringe is replenished with groundwater from the underlying aquifer, so it is also considered a loss of groundwater (Lubczynski, 2011).

The MODFLOW EVT package that the ET rate decreases with increasing depth to the water table because fewer shrub and tree roots are able to reach the water table and the energetics of withdrawing the water become less favorable. In the groundwater model, the consumptive use of groundwater due to ET decreases from the maximum rate when the water table is at the land surface and diminishes linearly down to zero when the water table reaches the extinction depth for that location.

In the Bedford-Coldwater Model, three ET zones were defined as shown on Figure 19. The first zone represents locations where aerial photographs indicate the presence of dense, lush riparian vegetation indicates areas of shallow groundwater where the plants (phreatophytes) can regularly uptake water directly from the water table to meet evaporative demand. These occur along the Temescal Wash and in the upper portions of some of the canyons along the basin margin. The extinction depth for these locations was set at 15 feet below the ground surface. Over most of the remaining model domain, the extinction depth was set at 7.5 feet to represent the vegetation in these areas. The third area represents areas where quarry lakes exist where the extinction depth was set at 3.0 feet to represent evaporation off of ponded water that periodically exists in these quarry areas. ET rates applied in the BedfordColdwater Model use the ET data from the rainfall-runoff-recharge model (see Section 3).

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4.3.5. Groundwater Pumping
Groundwater pumpage is the most significant groundwater outflow component for the basin.

Groundwater users in the Basin are required to report their pumping to Western Municipal Water District, which is one of several agencies responsible for administering adjudication decrees in the Upper Santa Ana River Watershed area. Thirty-eight wells within the Basin produced groundwater in one or more years during 1990-2018, and the reported annual pumping amounts were obtained from WMWD.

Figure 20 shows the locations of pumping in the Basin. Locations of agricultural pumping are distributed based on the estimated agriculture pumping requirements calculated using the rainfall-runoff model (Figure 21).

Annual production by all of the wells generally increased from 1990 to about 1999; however, from 2000 through 2007 annual production stabilized at about have the 1990-1999 rates, as shown in Figure 22. All pumping wells are included as analytical elements that are simulated by the MODFLOW well package in the model. Table 2 presents the overall trend in average annual groundwater pumping over time along with the assigned model layer for each well. In 2008, the City of Corona and Elsinore Valley Water District came to an agreement to limit groundwater pumping The citrus groves in the Basin were presumed to be irrigated by groundwater, although that pumping does not appear to be included in the WMWD production records. The amount of irrigation was estimated using the rainfall-runoff-recharge model and was assigned to hypothetical well locations at the center of each citrus recharge polygon. Some rural residences might be served by on-site domestic wells. The amount of pumping at those wells is assumed to be negligibly small in the context of the overall groundwater budget. Small domestic wells are not included in the WMWD database and are not included in the model.

4.3.6. Recycled Water Recharge Ponds
Reclaimed wastewater is percolated in ponds at the TVWD Water Reclamation Facility (WRF) (Figure 23). 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.

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). 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 MODFLOW Well Package was used to simulate recharge at the WRF recharge ponds. The wells were simulated as recharge wells. The volume of flow was distributed evenly over the area of the ponds. Prior to 2008, the recycled water recharge was applied to recharge located just south of the TVWD WRF.

Starting 2008, recycled water recharge was applied to new recharge ponds located just north of the TVWD WRF. The simulated recharge locations are shown on Figure 24.

4.3.7. Quarries
Sand and gravel mining has been the predominant industrial land use in the southern half of the Coldwater MA, an activity that continues today. Localized sand and gravel operations are also located

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along Temescal Wash in the Bedford MA (Figure 23). In addition, berms along washes, diversions of surface water, and the presence of large gravel pits enhance groundwater recharge of runoff in Coldwater area (Todd and AKM, 2008).

Discharge from the Coldwater MA quarry operations is from groundwater pumping, evapotranspiration, and other mining operations (MWH, 2004, Todd and AKM 2008). Losses also occur when the sand and gravel from the gravel pits, which contains groundwater used for washing, is transported from the Coldwater Basin. The estimated losses from gravel operations range from about 300 acre-feet per year (ft/yr to more than 900 acre-ft/yr (MWH, 2004). The average losses are approximately 700 acre-ft/yr (MWH, 2004). Quarry outflows were simulated using a combination of the EVT and Drain Packages. The ET rate and drain conductance were varied during model calibration to simulate the average annual losses from the MWH (2004) report that are listed above. The location of the boundary conditions for the Coldwater MA quarry operations are shown on Figure 24.

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 are 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 rainfallrunoff-recharge model for each stream is recharged to groundwater at the quarry location. This recharge from streamflow directed into the quarries is simulated using the MODFLOW well package. A portion of the monthly streamflow assigned from the rainfall-runoff model was moved from the SFR2 Package to the Well Package to simulate quarry inflow recharge.

In the Bedford area, the Mobile Sand quarry located just north of the Temescal WRF is open to potential outflows to Temescal Wash. To estimate groundwater outflows from the quarry pit during high groundwater levels, the MODFLOW model applies a boundary condition based on the observed water level in the pit to estimate the volume of quarry outflow. This is a head-dependent boundary condition that is able to calculate either quarry recharge or outflow based on groundwater conditions. This was simulated using the MODFLOW river package. Since we can estimate the water surface based on topography, the River Package can allow the quarry pit ponds to alternative from recharge to discharge based on monthly hydrologic conditions.

Quarry recharge in the Bedford MA is from streamflow from Brown and McBride Creeks flow 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 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. Similar to the Coldwater MA quarry recharge, recharge from streamflow directed into the quarries is simulated using the MODFLOW well package. A portion of the monthly streamflow assigned from the rainfall-runoff model was moved from the SFR2 Package to the Well Package to simulate quarry inflow recharge.

4.3.8. Subsurface Flow with Adjacent Groundwater Basins To simulate potential subsurface groundwater and outflow with adjacent groundwater basins, a specified head boundary was defined using the MODFLOW constant head package. Constant head boundaries allow sufficient inflow or outflow at that model cell to achieve the specified head. Where the

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Basin adjoins the Elsinore Valley and Temescal Basins, at the north and south ends of the model respectively, represent a very small percentage of the overall perimeter of the Basin.

Along the Elsinore Subbasin boundary, a constant head boundaries were set along a limited length of the boundary near Temescal Wash and another unnamed stream (Figure 24). The constant head along Temescal Wash was set at 1046.5 feet in Model Layer 2 and 3. Along the unnamed stream, the constant head was set at 1068.0 feet in Model Layer 2 and 3.

Along the Temescal Subbasin boundary, a similar set of constant head boundaries were set along a limited length of the boundary near Temescal Wash and another unnamed stream (Figure 24). The constant head along Temescal Wash was set at 765.0 feet in Model Layers 1, 2 and 3 for the first three years, and then set to 775.0 feet for the following twenty-six years. The constant head boundaries were based on an initial estimate that was refined during model calibration.

4.4. AQUIFER PROPERTIES
Aquifer properties represent the physical and hydrogeologic characteristics of the aquifers within the Basin that control groundwater flow. Aquifer properties must be assigned to each active grid cell in the model. The conceptual model provides the framework necessary to define aquifer properties.

4.4.1. Aquifer Characteristics
The groundwater model represents the basin fill materials in terms of their ability to store and transmit groundwater. Horizontal and vertical hydraulic conductivity define the permeability of the aquifer, which is its ability to transmit groundwater flow. The ability to store water consists of two components.

At the water table, storage of water associated with filling or draining the empty (air-filled) interstices between mineral grains is represented by the specific yield of the aquifer. In deep aquifers, there is a much smaller ability to store and release groundwater that derives from the compressibility of the water and aquifer materials (specific storativity). Thus, the initial response to pumping from a deep aquifer is a large drop in water level (head) within that aquifer. With sufficient time, however, the decrease in head creates downward movement of groundwater that eventually accesses the storage capacity at the water table. In other words, the storage response of the aquifer depends partly on the duration of pumping and observation. For groundwater management purposes, storage responses over periods of months to decades are usually the most relevant.

Aquifer characteristics can be estimated in two ways. The first is by means of an aquifer test in which one well is pumped while water levels are measured at a nearby well. This approach typically measures horizontal hydraulic conductivity over distances of tens to hundreds of feet and storage responses over periods of 1-3 days. The second approach is to calibrate a groundwater flow model such that the aquifer characteristics reproduce measured historical water levels throughout the basin given estimates of historical recharge and pumping. The latter approach produces estimates of aquifer characteristics averaged over spatial scales of thousands to tens of thousands of feet and time scales of months to decades. The estimates account for preferential flow through localized sand and gravel lenses in the basin fill materials and for delayed water-table responses to deep pumping. Also, model calibration provides estimates of vertical hydraulic conductivity across the layers of alluvial deposits, which is rarely measured by aquifer tests. The temporal and spatial scales represented by the model calibration approach are better for addressing most long-term groundwater management questions.

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4.4.2. Zone Approach
Because of the limited data for aquifer properties for the Basin, a zoned distribution pattern was used that applied aquifer properties over subregional areas with similar geologic conditions. Although the units are heterogeneous, the approach was to get a representative average value for each aquifer property for limited number of zones around the basin. This was to avoid the patchwork quilt type of aquifer property distribution that does not show any relation to the underlying geologic conditions that define the aquifer property.

Figures 25 shows the distribution of aquifer characteristics after calibration of hydraulic conductivity and specific storage, respectively. The initial estimates of hydraulic conductivity and specific yield were from available local data, which incorporated major geologic features such as relatively permeable sediments in the upper parts of alluvial fans.

4.4.3. Hydraulic Conductivity
Hydraulic conductivity represents the ability of the water to flow through the aquifer, and is defined horizontally within a model layer to represent groundwater flow through the aquifer and vertically between adjacent model layers to represent groundwater exchange between aquifers.

The definition of the horizontal hydraulic conductivity is based on an assessment of lithologic description, available aquifer test data and model calibration. Since each model layer represents a thick interval composed of varying lithologies, the horizontal hydraulic conductivity represents an average value over the entire vertical thickness that includes the finer-grained layers in addition to any specific sand and gravel zone. For the Bedford-Coldwater Model, horizontal hydraulic conductivity is defined using regionalized blocks based on the geologic character of the unit and refined during calibration.

The hydraulic conductivity used in the Bedford-Coldwater Model varies within a reasonable value range for the aquifer characteristics for each aquifer to achieve the model calibration. The horizontal hydraulic conductivities used in the Bedford-Coldwater Model are listed in Table 3.

4.4.4. Vertical Conductance
In general, groundwater flow within an aquifer is dominantly horizontal whereas flow between adjacent aquifers is essentially vertical. The application of vertical hydraulic conductivity recognizes the inherent isotropy present in natural geologic formations. Vertical groundwater flow is equivalent to Ohm’s Law for serial electrical flow through different resistivity layers. Based on this analogy, vertical groundwater flow, similar to serial electrical flow, is limited by the lowest conductivity (or highest resistivity) layer encountered. Therefore, vertical groundwater flow is defined by the lowest-permeability, continuous layer that controls the exchange of groundwater between aquifer or model layers.

In MODFLOW, vertical groundwater flow between model layers is calculated using vertical conductance (VCONT) that is calculated as the conductance of two one-half cells in a series with continuous saturation between them (Harbaugh, 2005). This calculation is performed within MODFLOW and requires the input of a vertical hydraulic conductivity (Kz) for each layer. In general, Kz values were set to allow relatively free exchange between layers. The vertical hydraulic conductivity values used in the model to calculate the VCONT are summarized in Table 3.

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4.4.5. Specific Yield and Specific Storage
Aquifer storage defines the ability of the aquifer to take in or release water. Under unconfined conditions, water released from or put into aquifer storage represents the physical draining of groundwater from interstitial pore space within the aquifer. Unconfined storage is defined by specific yield, which is typically consistent with the effective porosity of the aquifer. Under confined conditions, water released from or put into aquifer storage is derived from the compressibility of water as a result of changes in the aquifer pressure within the interstitial pore space.

MODFLOW 2005 requires the use of specific storage, which is in the units of feet-1. Reasonable ranges for the specific yield and specific storage were varied within a reasonable range during the model calibration and the values are listed in Table 3, respectively.

4.5. INITIAL CONDITION
The model also requires that groundwater levels be specified at the start of the simulation. They were estimated based on contouring of available water level data. As the initial heads may be dynamic and not representative of stable initial conditions, the first stress period representing pre-1990 conditions were run as steady-state to facilitate the calculation of a stable hydrologic system.

The transient model was used to develop the initial groundwater elevations that serve as the starting condition for the transient model. For this, groundwater pumping was applied to represent the longterm average pumping prior to 1990. The surface recharge component used to estimate groundwater recharge was set to a predevelopment condition to reduce the effect of urbanization. The results of the transient model provided a reasonable groundwater elevation data representing the late 1980’s to obtain an appropriate starting condition. This was an iterative process and the transient model used to develop the initial head was updated during the transient model calibration to incorporate significant changes in the model setup. Figure 26 provides the starting head for Layers 2, which provides a reasonable representation of the groundwater conditions for Layers 1 and 3.

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5. HISTORICAL MODEL RESULTS
The Bedford-Coldwater Model was calibrated using the developed calibration criteria to reduce uncertainty by matching model results to observed data. An extensive calibration process was designed to better constrain the range of aquifer properties and boundary conditions for the model, thereby reducing uncertainty in the results.

5.1. CALIBRATION METHODOLOGY
For the Bedford-Coldwater Model, the simulation is setup using a 29-year base period that covers Water Year (WY) 1990 to WY2018. This aspect of the calibration is important to demonstrate that the model has the capability to simulate historical changes in groundwater elevations, and is therefore capable of forecasting future changes in groundwater elevations. This capability is necessary for the model to serve as a useful groundwater management tool.

5.1.1. Approach
The transient calibration is a process that compares the simulated groundwater levels from the model to observed groundwater level measurements. During calibration, boundary condition parameters and aquifer properties are varied within the reasonable range defined by the hydrogeological conceptual model. Different combinations are tested to determine the set of parameters and properties that produce an acceptable correlation simulated to measured groundwater elevations over time. Other data sets, such as key water budget components, surface water conditions, or hydrogeological conceptual model, may be used to further constrain the calibration.

There are multiple combinations of aquifer properties and boundary conditions that can be used to match a single set of groundwater elevation data. Calibrating to multiple data sets under differing stresses (i.e. recharge and discharge rates) reduces this “non-uniqueness”, thereby reducing the uncertainty. Performing a comprehensive calibration over a 29-year base period infers the calibration has been performed over wet, dry, and normal years with varying degrees of pumping. To that end, the Bedford-Coldwater Model was primarily calibrated using groundwater levels. The measures of calibration are primarily from a statistical analysis along with a visual assessment groundwater level trends from hydrographs. The groundwater elevation maps and water budget data considered during the model calibration are assessed in context with the model results, so are discussed in the next section.

5.1.2. Calibration Methodology
Joint calibration of the rainfall-runoff-recharge model, the surface water budget models and the groundwater flow model applied heuristic methods (i.e. trial-and-error adjustments) to selected variables, as informed by the timing and location of model residuals. In accordance with the principle of parsimony in modeling (DWR, 2016), calibration began with a small number of broad zones for hydraulic conductivity and storage. Zones were subdivided during calibration if a pattern of residuals at multiple wells warranted it. Although storage and hydraulic conductivity are not necessarily correlated, in practice they often are to some degree. Thus, for simplicity, similar zonation patterns were used for both variables.

In practice, most of the calibration effort focused on adjustments to horizontal and vertical hydraulic conductivity, the locations and conductances of faults, stream bed vertical hydraulic conductivity, and

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several tributary watershed parameters: root depths of natural vegetation, rainfall-runoff thresholds and slopes, and the leakage and recession rates for shallow groundwater. Variables that were not adjusted during calibration include land use, crop root depths, pumping locations, and groundwater pumping.

Model performance during the calibration process was evaluated primarily by visual inspection of superimposed measured and simulated water-level hydrographs. Adjustments to model inputs and parameters were made only if two or more wells in a given area exhibited similar patterns of discrepancies between measured and simulated water levels. The process of manually calibrating a groundwater model also produces considerable insight into the groundwater flow system and the factors that influence it. Water levels for some wells were easy to reproduce with the model, while others were more difficult.

5.1.3. Primary and Alternative Calibration
In this report, we provide two sets of calibration results. Primarily, this was done to provide two variations for simulating the quarry operations in the Coldwater MA. These two calibration versions include:
• Primary Calibration – the Primary Calibration is the version of the historical model that is carried forward as the final model calibration that is used as the based for the projected future scenarios.
• Alternative Calibration – the Alternative Calibration is presented to demonstrate that uncertainty regarding the quarry operations, primarily in the Coldwater MA, may indicate a data gap. The Alternative Scenario is presented for informational purposes to document this work for future model updates, but it is not used for the projected future scenarios.

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 area, excavations occur within the large quarry pits following periods of high groundwater levels for the period from 1990 to 2010. Based on available information, no additional pumping to maintain quarry water levels was assumed to occur. However, 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.

For the Primary Calibration, quarry outflows were simulated using a combination of the EVT and Drain Packages (see Section 4.3.7). From 1990 to 2010, the quarry outflows were allowed to be higher assuming some limited additional pumping may have occurred. However, after 2010, no additional pumping to maintain quarry water levels has occurred and that is supported by the historical model calibration. The ET rate and drain conductance were varied during model calibration to simulate the average annual losses from the MWH (2004) report. However, the calibration results (see following discussion) did not fully capture the high and low observed groundwater near the Coldwater MA quarries.

For the Alternative Calibration, a different simulation method was applied at the quarry locations. The emphasis of the Alternative calibration was to apply a boundary condition that would more forcefully simulate the observed groundwater levels. For the Alternative Calibration, the quarry operations were simulated using the MODFLOW river package. The River Package can allow the quarry pit ponds to alternate from recharge to discharge based on monthly hydrologic conditions. We estimated the water surface based on a review of Google Earth satellite images of the quarries and other local reports.

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5.2. STATISTICAL CALIBRATION
The calibration was evaluated using a statistical comparison of difference (or residual) between measured and simulated groundwater elevations. The calibration was done for the entire Subbasin. In addition, a breakdown of the calibration results for each of the management areas is also provided.

5.2.1. Primary Calibration Results
For the Basin, the calibration is based on observed groundwater elevations from 3,736 measurements in 27 wells over the 29-year base period from October 1989 through September 2018 (WY1990-2018). The locations of these wells are shown on Figures 27 and 28 for the Bedford MA and Coldwater MA, respectively.

Next, a more rigorous calibration was performed involving a statistical analysis to compare the difference or residual between measured and simulated groundwater elevations. An initial comparison is made with a scatter plot (Figure 29) that depicts this relationship of observed versus simulated groundwater elevations. As indicated on Figure 29, the scatter along the correlation line is minor in comparison to the range of the data. The correlation coefficient for the data on this graph is 0.905. The correlation coefficient ranges from 0 to 1 and is a measure of the closeness of fit of the data to a 1 to 1 correlation. A correlation of 1 is a perfect correlation. The correlation coefficient of 0.905 indicates a strong correlation between simulated and observed groundwater elevations.

A more detailed statistical analysis is provided that compares the difference, or residual, between measured and simulated groundwater elevations. Table 4 summarizes statistical measures used to assess the calibration. A brief summary of the statistical measures used to evaluate the calibration results shown on Table 4 is summarized below:
• The residual mean is computed by dividing the sum of the residuals by the number of residual data values. The closer this value is to zero, the better the calibration especially as related to the water balance and estimating the change in aquifer storage. The residual mean is 16.0 feet. • The absolute residual mean is the arithmetic average for the absolute value of the residual so it provides a measure of the overall error in the model. The absolute residual mean is 42.1 feet. • The residual standard deviation evaluates the scatter of the data. A lower standard deviation indicates a closer fit between the simulated and observed data. The standard deviation for the calibrated model is 31.5 feet.
• The Root Mean Square (RMS) Error is the square root of the arithmetic mean of the squares of the residuals is provides another measure of the overall error in the model. The RMS Error for the calibrated model is 45.0 feet.
• The scaled absolute residual the ratio of the absolute residual mean is divided by the range of observed groundwater elevations. This ratio helps to put the variation of the residuals into perspective with respect to the scale of the groundwater basin. This ratio for the BedfordColdwater Model is 0.077, which puts the statistical variability at less than 8 percent of the range. A ratio below 0.15 is generally considered a well calibrated (ESI 2011).

It should be noted that some degree of difference (or residual) between the observed and simulated groundwater elevations is expected. Residuals may be due in part to localized effects or data quality issues. For example, residuals can result from using groundwater elevations from pumping wells as calibration targets. MODFLOW calculates the groundwater elevation for the center of a model cell