Agenda packet — City Council and Concurrent Authorities, March 18, 2025 (part 3 of 5)

NEVADA ST,

STOCKTON, CA
95205
BP23-07085 ADUR1 4/8/2024
1 1 4/8/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

The percentage of accessory dwelling units per income category, is based on the affordability analysis in the Accessory Dwelling Unit Potential section of the City of Stockton 2023-2031 Housing Element, Section 4, Housing Sites Inventory, Pg 224-225. (Link to Housing Element:
https://cms3.revize.com/revize/stockton/Documents/Business/Planning & Engineering/Shape Stockton/(New) Adopted Housing Element_ July 2024.pdf.) The income level for this parcel was decided based on the geographic location within the city. Low Income (31) or 60% of building permits, are parcels mostly south of Harding Way. Some ADU’s are along Wilson Way near Bradford Street. Moderate Income (16) or 30% of building permits, are north of Harding Way to slightly north of Hammer Lane. Above Moderate Income (5) or 10% of building permits, are between Hammer Lane and Eight Mile Road. This generally is shown in Figure HE-2: Median Household Incomes of the Housing Element, Pg 105. (The median income is higher in north Stockton than in south Stockton)
07704308
2628 CYPRESS

AV, STOCKTON,
CA 95207
BP23-06743 ADUR1 4/11/2024
1 1 4/11/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

STOCKTON, CA
95205
BP23-08326 ADUR1 4/22/2024
1 1 4/22/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

AV, STOCKTON,
CA 95205
BP23-07214 ADUR1 4/26/2024
1 1 4/26/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

WY, STOCKTON,
CA 95209
BP23-08068 ADUR1 5/2/2024
1 1 5/2/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

ST, STOCKTON,
CA 95206
BP23-05146 ADUR1 5/22/2024
1 1 5/22/202411 10/1/20241
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

NEVADA ST,

STOCKTON, CA
95205
BP24-00215 ADUR1 5/24/2024
1 1 5/24/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

CREEK DR,

STOCKTON, CA
95209
BP24-00725 ADUR1 6/6/2024
1 1 6/6/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

STOCKTON, CA
95207
BP24-03063 ADUR1 6/7/2024
1 1 6/7/202411 12/3/20241
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

ST, STOCKTON,
CA 95203
BP23-09136 ADUR1 6/11/2024
1 1 6/11/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

CT, STOCKTON,
CA 95206
BP24-00059 ADUR1 6/17/2024
1 1 6/17/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

ST, STOCKTON,
CA 95204
BP24-01038 ADUR1 6/21/2024
1 1 6/21/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

ATTACHMENT B
676
Jurisdiction Stockton ANNUAL ELEMENT PROGRESS REPORT
Reporting Year 2024 (Jan. 1 - Dec. 31) Housing Element Implementation Cells in grey contain auto-calculation formulas Planning Period 6th Cycle 12/31/2023 - 12/31/2031
Note: "+" indicates an optional field
15133103
1222 E WORTH

ST, STOCKTON,
CA 95205
BP23-09574 ADUR1 7/1/2024
1 1 7/1/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

STOCKTON, CA
95209
BP23-04507 ADUR1 7/5/2024
1 1 7/5/202410
The percentage of accessory dwelling units per income category, is based on the affordability analysis in the Accessory Dwelling Unit Potential section of the City of Stockton 2023-2031 Housing Element, Section 4, Housing Sites Inventory, Pg 224-225. (Link to Housing Element:
https://cms3.revize.com/revize/stockton/Documents/Business/Planning & Engineering/Shape Stockton/(New) Adopted Housing Element_ July 2024.pdf.) The income level for this parcel was decided based on the geographic location within the city. Low Income (31) or 60% of building permits, are parcels mostly south of Harding Way. Some ADU’s are along Wilson Way near Bradford Street. Moderate Income (16) or 30% of building permits, are north of Harding Way to slightly north of Hammer Lane. Above Moderate Income (5) or 10% of building permits, are between Hammer Lane and Eight Mile Road. This generally is shown in Figure HE-2: Median Household Incomes of the Housing Element, Pg 105. (The median income is higher in north Stockton than in south Stockton)
11723420
1560

SUNNYSIDE AV,

STOCKTON, CA
95205
BP23-08561 ADUR1 8/5/2024
1 1 8/5/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

VALLEY LN,

STOCKTON, CA
95205
BP24-03500 ADUR1 8/8/2024
1 1 8/8/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

DR, STOCKTON,
CA 95209
BP24-01606 ADUR1 8/16/2024
1 1 8/16/202410
The percentage of accessory dwelling units per income category, is based on the affordability analysis in the Accessory Dwelling Unit Potential section of the City of Stockton 2023-2031 Housing Element, Section 4, Housing Sites Inventory, Pg 224-225. (Link to Housing Element:
https://cms3.revize.com/revize/stockton/Documents/Business/Planning & Engineering/Shape Stockton/(New) Adopted Housing Element_ July 2024.pdf.) The income level for this parcel was decided based on the geographic location within the city. Low Income (31) or 60% of building permits, are parcels mostly south of Harding Way. Some ADU’s are along Wilson Way near Bradford Street. Moderate Income (16) or 30% of building permits, are north of Harding Way to slightly north of Hammer Lane. Above Moderate Income (5) or 10% of building permits, are between Hammer Lane and Eight Mile Road. This generally is shown in Figure HE-2: Median Household Incomes of the Housing Element, Pg 105. (The median income is higher in north Stockton than in south Stockton)
15311402
2110 E WEBER

AV, STOCKTON,
CA 95205
BP24-01100 ADUR1 8/21/2024
1 1 8/21/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

STOCKTON, CA
95202
BP24-04243 ADUR1 8/26/2024
1 1 8/26/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

STOCKTON, CA
95203
BP23-09457 ADUR1 8/26/2024
1 1 8/26/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

RANCH CT,

STOCKTON, CA
95206
BP24-03619 ADUR1 8/27/2024
1 1 8/27/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

WY, STOCKTON,
CA 95205
BP23-09575 ADUR1 9/12/2024
1 1 9/12/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

STOCKTON, CA
95210
BP24-00219 ADUR1 9/16/2024
1 1 9/16/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

AV, STOCKTON,
CA 95204
BP24-02739 ADUR1 9/23/2024
1 1 9/23/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

AV, STOCKTON,
CA 95203
BP24-06662 ADUR1 10/7/2024
1 1 10/7/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

ST, STOCKTON,
CA 95206
BP24-03634 ADUR1 10/17/2024
1 1 10/17/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

ST, STOCKTON,
CA 95205
BP24-07985 ADUR1 10/25/2024
1 1 10/25/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

STOCKTON, CA
95206
BP24-03145 ADUR1 10/28/2024
1 1 10/28/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

ATTACHMENT B
677
Jurisdiction Stockton ANNUAL ELEMENT PROGRESS REPORT
Reporting Year 2024 (Jan. 1 - Dec. 31) Housing Element Implementation Cells in grey contain auto-calculation formulas Planning Period 6th Cycle 12/31/2023 - 12/31/2031
Note: "+" indicates an optional field
11318017
2121 LAKESIDE

AV, STOCKTON,
CA 95204
BP24-00401 ADUR1 10/28/2024
1 1 10/28/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

STOCKTON, CA
95209
BP24-03054 ADUR1 10/29/2024
1 1 10/29/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

MONTAUBAN AV,

STOCKTON, CA
95210
BP24-00835 ADUR1 10/29/2024
1 1 10/29/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

ST, STOCKTON,
CA 95206
BP24-08052 ADUR1 10/30/2024
1 1 10/30/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

THAYER CI,

STOCKTON, CA
95206
BP24-03040 ADUR1 11/13/2024
1 1 11/13/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

MELBOURNE AV,

STOCKTON, CA
95203
BP24-08272 ADUR1 11/18/2024
1 1 11/18/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

ST, STOCKTON,
CA 95206
BP24-03321 ADUR1 11/19/2024
1 1 11/19/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

PL, STOCKTON,
CA 95210
BP24-07166 ADUR1 12/6/2024
1 1 12/6/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

ST, STOCKTON,
CA 95203
BP24-01589 ADUR1 12/9/2024
1 1 12/9/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

HACKBERRY ST,

STOCKTON, CA
95205
BP23-03874 ADUR1 12/30/2024
1 1 12/30/202410
See notes. The percentage of
accessory dwelling units per
income category is based on
the City of Stockton Housing
Element.

CT, STOCKTON,
CA 95209
BP24-09024 ADUR1 12/30/2024
1 1 12/30/202410
The percentage of accessory dwelling units per income category, is based on the affordability analysis in the Accessory Dwelling Unit Potential section of the City of Stockton 2023-2031 Housing Element, Section 4, Housing Sites Inventory, Pg 224-225. (Link to Housing Element:
https://cms3.revize.com/revize/stockton/Documents/Business/Planning & Engineering/Shape Stockton/(New) Adopted Housing Element_ July 2024.pdf.) The income level for this parcel was decided based on the geographic location within the city. Low Income (31) or 60% of building permits, are parcels mostly south of Harding Way. Some ADU’s are along Wilson Way near Bradford Street. Moderate Income (16) or 30% of building permits, are north of Harding Way to slightly north of Hammer Lane. Above Moderate Income (5) or 10% of building permits, are between Hammer Lane and Eight Mile Road. This generally is shown in Figure HE-2: Median Household Incomes of the Housing Element, Pg 105. (The median income is higher in north Stockton than in south Stockton)

ATTACHMENT B
678
Jurisdiction Stockton ANNUAL ELEMENT PROGRESS REPORT
Reporting Year 2024 (Jan. 1 - Dec. 31) Housing Element Implementation Planning Period 6th Cycle 12/31/2023 - 12/31/2031
1 Projection Period 3 4
RHNA Allocation by
Income Level
Projection Period -
06/30/2023-
12/30/2023
2023 2024 2025 2026 2027 2028 2029 2030 2031 Total Units to Date (all years)
Total Remaining
RHNA by Income
Level
Deed Restricted - - 51 - - - - - - -
Non-Deed Restricted - - 202 - - - - - - -
Deed Restricted - - - - - - - - - -
Non-Deed Restricted 26 - 31 - - - - - - -
Deed Restricted - - - - - - - - - -
Non-Deed Restricted - - 16 - - - - - - -
Above Moderate 6,072 241 - 537 - - - - - - - 778 5,294
12,672
267 - 837 - - - - - - - 1,104 11,568
5 6 7
Extremely low-Income
Need 2023 2024 2025 2026 2027 2028 2029 2030 2031
Total Units to
Date
Total Units
Remaining
1,233 - 202 - - - - - - - 202 1,031
VLI Deed Restricted
VLI Non Deed Restricted
LI Deed Restricted
LI Non Deed Restricted
MI Deed Restricted
MI Non Deed Restricted
Above Mod Income
Please note: The APR form can only display data for one planning period. To view progress for a different planning period, you may login to HCD's online APR system, or contact HCD staff at [email protected].
2,571
253
This table is auto-populated once you enter your jurisdiction name and current year data. Past year information comes from previous APRs.
16 Moderate
2,465
1,548
2,587
Please contact HCD if your data is different than the material supplied here 57 2
Table B
Regional Housing Needs Allocation Progress
Permitted Units Issued by Affordability
2,212
1,491
Please note: For the last year of the 5th cycle, Table B will only include units that were permitted during the portion of the year that was in the 5th cycle. For the first year of the 6th cycle, Table B will only include units that were permitted since the start of the planning period. Projection Period units are in a separate column.

Total RHNA
Total Units
Income Level
Very Low
Low
Extremely Low-Income Units*
Note: units serving extremely low-income households are included in the very low-income RHNA progress and must be reported as very low-income units in section 7 of Table A2. They must also be reported in the extremely low-income category (section 13) in Table A2 to be counted as progress toward meeting the extremely low-income housing need determined pursuant to Government Code 65583(a)(1). *Extremely low-income housing need determined pursuant to Government Code 65583(a)(1). Value in Section 5 is default value, assumed to be half of the very low-income RHNA. May be overwritten.

Progress toward extremely low-income housing need, as determined pursuant to Government Code 65583(a)(1).

Please Note: Table B does not currently contain data from Table F or Table F2 for prior years. You may login to the APR system to see Table B that contains this data.

ATTACHMENT B
679
Jurisdiction Stockton ANNUAL ELEMENT PROGRESS REPORT
Reporting Year 2024 (Jan. 1 - Dec. 31) Housing Element Implementation Planning Period 6th Cycle 12/31/2023 - 12/31/2031
Date of Rezone Rezone Type
2 4 5 6 7 9 10 11
APN Street Address Project Name+
Local
Jurisdiction
Tracking ID+
Date of Rezone Very Low-Income Low-Income Moderate-Income Above ModerateIncome Rezone Type Parcel Size
(Acres)
General Plan
Designation Zoning Minimum Density Allowed
Maximum
Density Allowed
Realistic
Capacity Vacant/Nonvacant Description of Existing Uses
Note: "+" indicates an optional field
Cells in grey contain auto-calculation formulas
Summary Row: Start Data Entry Below
3 8
Project Identifier RHNA Shortfall by Household Income Category Sites Description 1 Sites Identified or Rezoned to Accommodate Shortfall Housing Need and No Net-Loss Law Table C

ATTACHMENT B
680
Jurisdiction Stockton
Reporting Year 2024 (Jan. 1 - Dec. 31)
1 2 3 4
Name of Program Objective Timeframe in H.E Status of Program Implementation

1. Adequate Sites
Monitoring and No Net
Loss
Continue to maintain sufficient sites to
address 12,673 units
Update inventory annually as part of the
Housing Element Annual Progress Report
and assess “no net loss” as projects
come forward on Housing Element sites.

Assess project approvals on Housing
Element inventory sites as of December
31, 2027. If approved projects are not in
line with the City’s non-residential RHNA
projections in the inventory, within one
year (by December 31, 2028) the City will
identify additional sites beyond the sites
in the inventory that allow non-residential
uses in order to further facilitate
residential development.

Ongoing. RHNA sites are posted online and "no net loss" findings will be prepared for all RHNA sites. Link to RHNA sites:
[https://cms3.revize.com/revize/stockton/Documents/Business/Planning%20&%20Engineering/Shape%20Stockton/NEW_OpportunitiesSites_CityWebsiteHousingElementPage_02-04-2025.pdf]. Permit approvals credited towards meeting RHNA will be posted annually as part of the state required annual updates in April of each year. Staff will monitor the status of the approved RHNA projects by 2027 to see if they are built to their approved unit count.

2. Downtown
Implementation
4,400 residential units in the Greater
Downtown Area by 2040
Adopt Comprehensive Development
Code Update and HAP by April 2024; and
annually thereafter to identify any
additional strategies to address General
Plan goals.

Ongoing. Action Plans were adopted in November 2024 (Resolution 2024-11-19-1504. Online Link: https://stockton.granicus.com/MinutesViewer.php?view_id=48&clip_id=8863). The draft Development Code is anticipated to go before the Stockton City Council for consideration in Summer/Fall 2025.

3. Sites Included in
Previous Housing
Elements
437 residential units on 16 repeat sites
identified in Appendix A that don’t
already allow residential development by
right.

Update Development Code and, if
needed, Land Use Element by December
31, 2026
Ongoing. The draft Development Code is anticipated to go before the Stockton City Council for consideration in Summer/Fall 2025. The current code, which allows residential uses at all income levels to be processed ministerial by staff (regardless of state preemption), will continue into the proposed draft Development Code, which is anticipated to go before the City Council for consideration in Summer/Fall 2025. The Land Use Element does not require an update at this time. The 437 residential units on the 16 repeat sites identified in Appendix A will be tracked by staff.

4. Public Facilities Repair
and Replacement
5 public facility/ infrastructure projects,
prioritizing lower-income, high-poverty
neighborhoods such as the South
Stockton neighborhood, Downtown, and
parts of the East Stockton and Pacific
Avenue/Lincoln Village neighborhoods.

Annually Ongoing. A new Consolidated Plan is under development and is anticipated to go before the Stockton City Council for consideration in April 2025, and potentially taking effect July 1, 2025. The existing Consolidated Plan is online for public use; however, it does not allow for funding to be used for public facility improvements. The new Consolidated Plan is anticipated to contain goals that allow for these types of improvements.

5. Housing and
Neighborhood Action
Plans
Permit 1,000 residential units, prioritizing
affordable housing in high-opportunity
areas such as the Morada/Holman,
Brookside/Country Club, Eight Mile/Bear
Creek, and Midtown neighborhoods.

Additional focus will be given to
eliminating barriers to housing
construction in lower-income areas such
as the Cabral Station Area and Little
Manila/Gleason Park neighborhoods.

Neighborhood Action Plans - December
2023; Housing Action Plan – April 2024
Ongoing. Action Plans were adopted in November 2024 (Resolution 2024-11-19-1504. Online Link: https://stockton.granicus.com/MinutesViewer.php?view_id=48&clip_id=8863) and included content that was carried over into the draft Development Code update to go before the City Council for consideration in Summer/Fall 2025.

6. Accessory Dwelling
Units
Approve 180 ADUs over the course of
the planning period, targeting areas of
high opportunity, specifically the
following neighborhoods -
Brookside/Country Club, Weston Ranch,
Eight Mile/Bear Creek, Midtown around
the University of the Pacific (between I-5
and “Miracle Mile/Pacific Avenue),
western Upper Hammer/Thornton Rd,
and eastern Morada/Holman.

The City is currently updating the ADU
regulations as part of the Comprehensive
Development Code Update, to be
completed by April 2024. Starting in
November 2024, evaluate the consistency
of Stockton’s ADU regulations with State
law and update accordingly. Continue to
make ADU materials available; evaluate
effectiveness of ADU approvals every
other year, starting April 2025; and,
identify additional site capacity, if
needed, by December 2026. Apply
annually, or as grants are available, for
funding to support ADU incentives.

Ongoing. The draft Development Code update to go before the Stockton City Council for consideration in Summer/Fall 2025. ADU submission checklist handouts are available to the public. Future amendments over ADU regulations may be considered. 52 ADU and JADU building permits in 2024. 23 of the permits were within the indicated neighborhoods. There is a handout available to the public that describes the submittal requirements for city pre-approved ADUs.

7. Infill Strategy
100 extremely low-income units and 150
other lower income units; funding for 10
brownfield sites minimum to promote
new housing choices and affordability in
areas of opportunity.

Continue to offer the Downtown
Infrastructure Infill Incentive Program.

Adopt Housing Action Plan by April 2024.

Implement Housing Action Plan
strategies by 2025. Annually, beginning
in 2026, identify any additional strategies
needed to address overpayment and
reduce displacement risk and implement
them within 2 years of identification.

Ongoing; however, the funding provided under the Downtown Infill Infrastructure Program was reallocated by the Stockton City Council on May 14, 2024 for the creation of the city’s Redevelopment Fund to be used for property acquisition, demolition, and environmental clearance activities in support of the city’s infill strategy. Efforts are underway for strategic site assembly in the Downtown area and other areas of opportunity. Action Plans were adopted in November 2024 (Resolution 2024-11-19-1504. Online Link: https://stockton.granicus.com/MinutesViewer.php?view_id=48&clip_id=8863). Content, such as strategies to streamline were also included into the draft Development Code update to go before the City Council for consideration in Summer/Fall 2025. Staff will continue to track the extremely low-income, lower income units and funding opportunities for brownfield sites.

ANNUAL ELEMENT PROGRESS REPORT
Housing Element Implementation
Housing Programs Progress Report
Describe progress of all programs including local efforts to remove governmental constraints to the maintenance, improvement, and development of housing as identified in the housing element.

Table D
Program Implementation Status pursuant to GC Section 65583

ATTACHMENT B
681

8. Site Assembly
Support at least 5 lot consolidations on
sites with lower income units during the
planning period. Facilitate lot
consolidation to produce sites for 2,300
moderate and above moderate
residential units to produce new housing
opportunities throughout city.

Establish a program or resources to
connect property owners and developers
by December 2025, and assess incentives
and resources thereafter. Ongoing:

Support consolidation as applicable
housing applications are received;
Pursue grant funding during planning
period if California legislation and/or
programs enable a tax-increment or
similar program that leads to funding for
site assembly.

Ongoing for mapping small vacant and underutilized sites to focus existing processes. Action Plans were adopted in November 2024 (Resolution 2024-11-19-1504. Online Link:
https://stockton.granicus.com/MinutesViewer.php?view_id=48&clip_id=8863). In addition, staff developed a Surplus Property landing page at https://stocktonca.gov/surplus and released a Request for Interest / Statement of Qualifications (RFI/SOQ) process for Development or Partnership Opportunities for interested applicants/developers to propose on available city surplus sites. Grant funding is also being pursued, including Regional Early Action Planning (REAP) 2.0, to establish potential vehicles for tax-increment or similar programs. Program for incentives and resources are also being explored during 2025.

9. Government-Owned
Sites
Facilitate development of governmentowned sites for 100 lower-income units and 594 above moderate-income units to
produce new housing opportunities
throughout city.

Coordinate with SDSU quarterly, starting
immediately, with the goal of
development of the sites by 2028.

City-Owned Sites 4-96, 4-97, 4-230, 4-33, 4-
231, 4-232, 3-74, 4-183: RFI/SOQ Issued:

Q4 2023, Entitlements: June 2025,
Building Permits: December 2025,
Construction Complete: June 2027.

City-Owned Sites 1-18, 1-19, 1-20, 1-21:

RFP previously released in 2020,
Entitlements: October 2024, Building
Permits: May 2025, Construction
Complete: July 2027.

City-Owned Sites 4-67, 4-210: RFI/SOQ
Issued: Anticipated Q2 2025,
Entitlements: June 2026, Building
Permits: December 2026, Construction
Complete: June 2028.

If a plan for housing development on
these parcels is not underway by 2026,
with building permits issued by June
2029 the City will identify additional sites
for housing accordingly, including
rezoning sites to address the RHNA if
needed.

Ongoing. City owned sites and RHNA sites are shown on the city website. Link to RHNA sites:
[https://cms3.revize.com/revize/stockton/Documents/Business/Planning%20&%20Engineering/Shape%20Stockton/NEW_OpportunitiesSites_CityWebsiteHousingElementPage_02-04-2025.pdf]. The city-owned sites that have been declared surplus and are available for disposition are listed on the Surplus Property landing page at [https://stocktonca.gov/surplus] and many are listed in the aforementioned RFI/SOQ. The development of government-owned sites will be tracked by staff. In February 2024, the Stockton City Council authorized a Development & Disposition Agreement (DDA) for the development of 520+ units of mixed-unit housing on the 9-acre city-owned site known as South Pointe. The development is pending site remediation, funded by the Department of Toxic Substances Control’s (DTSC) Equitable Community Revitalization Grant (ECRG) Program. [Link to ECRG: https://dtsc.ca.gov/ecrg/].

10. Large Site
Development
Facilitate large lot development,
including lot splits, as needed to
produce sites for 1,512 lower-income
units to produce new housing
opportunities throughout city.
•Conduct one-on-one meetings with
developers and property owners.
•Proactively conduct outreach
advertising available incentives,
resources, and relevant information for
the development of larger sites.
•Establish, maintain, and promote an
inventory of large sites appropriate for
residential development.
•Facilitate and streamline parceling, or
other similar planning methods, to
encourage the development of large
sites with affordable housing
components.

Ongoing, as projects come forward;
establish program to connect property
owners and developers by December
2025. Annually reach out to developers to
gather input on available incentives.

Annually conduct outreach and
advertising. Facilitate and streamline
parceling, or other similar actions, for
large sites through 2031. Assess project
approvals on large Housing Element
inventory sites as of December 31, 2027.

If approved projects are not in line with
the City’s RHNA projections on large
sites in the inventory, within one year (by
December 31, 2028) the City will identify
additional sites beyond the large sites in
the inventory in order to further facilitate
residential development and if necessary
will rezone to make the sites available for
residential development.

Ongoing for mapping large vacant and underutilized sites to focus existing processes. During 2024, the city continued to release Notice of Funding Availability (NOFA) processes to provide funding from the U.S. Department of Housing & Urban Development (HUD) for the development of affordable housing, oftentimes for large site development. The city meets regularly with affordable housing developers to navigate the development process and posts regularly on the city website and social media to notify developers of upcoming opportunities.

11. Coordination with the
Housing Authority of San
Joaquin County
Provide vouchers to 3,800 households in
Stockton and assist these lower income
households in accessing rental
opportunities with Housing Choice
Vouchers to facilitate housing mobility.

Target additional outreach in areas with
the highest concentration of children in
single female-headed households,
including parts of the Weston/Van
Buskirk neighborhood, Downtown, and
South Stockton.

Ongoing; establish education program by
the end of 2024 and distribute
information. Then distribute information
at least annually through the end of the
planning period.

Ongoing. The city coordinates frequently on a number of affordable housing projects, both for new construction and conversion/rehabilitation for the production of affordable housing.

12. State and Federal
Funding
Fund 200 extremely low-, 400 very low-,
450 low-income units; Provide down
payment assistance to 75 low-income
households, particularly in high
opportunity areas such as the
Morada/Holman, Brookside/Country
Club, Eight Mile/Bear Creek, and
Midtown neighborhoods.

Review funding opportunities annually;
down payment assistance program is
ongoing.

Ongoing. The city actively pursues available state and federal funding for the production of affordable housing, in the Pro-housing Incentive Pilot (PIP) Program. The Downtown Payment Assistance Program is currently being revamped, as the high interest rate environment poses challenges for efficient implementation.

13. Priority Sewer and
Water Service for
Affordable Housing
Include in Development Code as part of
Comprehensive Update
Include in Development Code as part of
Comprehensive Update by April 2024. The priority sewer and water service for affordable housing included as a proposed revision in the draft Development Code anticipated to be presented to the Stockton City Council for consideration in Summer/Fall 2025.

ATTACHMENT B
682

14. Property Assessed
Clean Energy (PACE)
Program
Connect 60 eligible Stockton residents
with energy- and cost-saving programs
to reduce overpayment on housing
costs. Program outreach will be
prioritized in areas with high rates of
homeowner overpayment, including the
Mariposa Lakes neighborhood, parts of
Downtown and East Stockton, the
Industrial Annex area, and parts of the
Pacific Avenue/Lincoln Village and
Weston/Van Buskirk neighborhoods.

Ongoing. A unique, centralized location
for this program on the City’s website will
be created by December 2025. Annual
updating will occur thereafter.

Ongoing. The city will continue to make progress in 2025 to provide a unique, centralized location for this program on the city’s website. In addition, the city administers Homeowner Rehabilitation Programs to provide opportunities for low-income Stockton homeowners to perform emergency repairs and deferred maintenance improvements on their properties, which can help to reduce energy costs. The city has a grant-funded Climate Careers Energy & Water program through our non-profit partner Rising Sun Center for Opportunity, as well as our grant-funded single-family solar program through our non-profit partner GRID North Valley. These programs are funded by the Transformative Climate Community (TCC) Round 4 Implementation Grant. [Note: The TCC project area is restricted to a 5sq. mi. area, largely in downtown/south Stockton. You can see the project area under the TCC layer on mapgeo:
https://stocktonca.mapgeo.io/datasets/properties?abuttersDistance=100&latlng=37.936145%2C-121.280598&panel=themes&themes=%5B%22d63390fc-4ecd-4a0f-8a5f-b1a80494a005%22%5D&zoom=14] The program data available is from 10/1/23 - 11/19/24:
•Climate Careers Energy & Water: 136 homes received Green House call services and retrofits – of those, 73 received smart thermostats and 45 received low-flow toilets •Single-Family Solar: Installed 164.1 kW out of the 393kW goal. Average system size is 4.3 kW. 33 fully completed installations and of those 20 have needed re-roofs, 7 have received electric panel upgrades, 1 partial repair, and 4 tree trimming/removal.

15. Green-Up Stockton
Connect 60 eligible Stockton residents
with energy- and cost-saving programs
to reduce overpayment on housing
costs. Program outreach will be
prioritized in areas with high rates of
homeowner or renter overpayment,
including the South and East Stockton,
Midtown, Industrial Annex, Downtown,
and Mariposa Lakes neighborhoods.

Ongoing
Ongoing. The city has a grant-funded Climate Careers Energy & Water program through our non-profit partner Rising Sun Center for Opportunity, as well as our grant-funded single-family solar program through our non-profit partner GRID North Valley. These programs are funded by the Transformative Climate Community (TCC) Round 4 Implementation Grant. [Note: The TCC project area is restricted to a 5sq. mi. area, largely in downtown/south Stockton. You can see the project area under the TCC layer on mapgeo: https://stocktonca.mapgeo.io/datasets/properties?abuttersDistance=100&latlng=37.936145%2C-121.280598&panel=themes&themes=%5B%22d63390fc-4ecd-4a0f-8a5f-b1a80494a005%22%5D&zoom=14] The program data available is from 10/1/23 - 11/19/24:
•Climate Careers Energy & Water: 136 homes received Green House call services and retrofits – of those, 73 received smart thermostats and 45 received low-flow toilets •Single-Family Solar: Installed 164.1 kW out of the 393kW goal. Average system size is 4.3 kW. 33 fully completed installations and of those 20 have needed re-roofs, 7 have received electric panel upgrades, 1 partial repair, and 4 tree trimming/removal.

16. Weatherization
Activities
200 units weatherized. Program outreach
will be prioritized in lower-income
neighborhoods and areas with high rates
of homeowner or renter overpayment,
including the South and East Stockton,
Midtown, Industrial Annex, Downtown,
and Mariposa Lakes neighborhoods.

Additionally, outreach will be prioritized
in the area southeast of the intersection
of Thornton Road/Pacific Avenue and
West Hammer Lane, where the city may
be able to reach more senior
households. Additional program
outreach will target areas in relative
proximity to agricultural employment
including parts of the Weston/Van
Buskirk neighborhood, the Industrial
Annex, the Morada/Holman
neighborhood, and the North Stockton
Annex neighborhood. Additional
outreach will be targeted in areas with
the highest concentration of children in
single female-headed households,
including parts of the Weston/Van
Buskirk neighborhood, Downtown, and
South Stockton.

Program availability is ongoing.

Advertising of the program by the City on
the City website and direct outreach will
begin by December 2024.

Ongoing. The city administers Homeowner Rehabilitation Programs to provide opportunities for low-income Stockton homeowners to perform emergency repairs and deferred maintenance improvements on their properties, which can help to reduce energy costs.

17. Development Code
Revisions N/A April 2024 Ongoing. The proposed revisions in the draft Development Code is anticipated to be presented to the Stockton City Council for consideration in Summer/Fall 2025.

18. Fiscally Positive Impact
Fees
Provide exemptions and reductions to
200 housing units to reduce
overpayment for housing costs and
reduce displacement risk specifically for
lower-income communities, including 30
units affordable to extremely low-income
households.

Annually, evaluate exemptions provided
and determine whether all constraints to
housing development associated with
impact fees or other funding mechanisms
are sufficiently addressed. If it is found
that they are not being addressed,
modifications will be made to one or
more exemption programs within one
year. This will occur after each annual
review until the end of the planning
period. The City will evaluate the
feasibility of providing impact or other
development fee waivers or deferrals for
projects with extremely low-income units
by the end of 2025.

Ongoing. Public Facility Fees (PFF) Impact Fee updates anticipated to occur in 2025 that will discuss fee exemptions and reductions.

19. Streamline Approvals
for Affordable Housing
Projects
150 new affordable units permitted
through SB 35 approval streamlining and
development of 150 affordable units
facilitated by using the adopted
preliminary application form.

Develop or adopt HCD’s SB 330
preliminary application form and develop
an SB 35 streamlined approval process
by December 2024 and implement as
applications are received. The City will
implement a minimum of two of the
options listed in Program 19, to further
streamline approvals and support
affordable housing projects by December
2026.

Information will be provided to future applicants interested in SB35 and SB330 preemptions. The city currently allows most residential uses (single family, multi-unit, and multifamily) by-right in most residential and commercial zones. Design review for all applications (residential and nonresidential) is ministerial if no other discretionary action is needed. This means by-right housing only requires ministerial design review prior to building permit approval. The Program 19 options implementation is ongoing. These options include: •Community benefit options that could be included in the criteria for initiating modified and new Development Agreements. These benefits could include Inclusionary Housing requirements and fees, Community Benefit agreements, increased land dedications for future city services, and joint-lease agreements for schools and civic uses.
• Other community benefits the City will explore to prevent displacement include a right to counsel program, tenant bill of rights, housing trust fund, rent escrow account program, and land banking. If additional community benefits are approved, put into place by December 2024.
• Additional funding for pre-construction analysis and remediation of infill sites for affordable housing projects and/or infill sites in low-resource areas. • Additional funding for infrastructure deficiency analysis and improvements in low-income and low resource areas. • Update the Citywide Public Facilities Fees (i.e., Impact Fees), and determine the current cost for providing services to underserved areas, adjust fees accordingly and provide waivers for affordable housing projects. • Outreach to establish working community groups within low-resource areas to determine needs and establish community partners for future housing projects.

20. Density Bonuses
Facilitate the construction of 1,000 lowerincome units to increase mobility opportunities; encourage density bonus
units in high-resource areas.

Complete as part of Comprehensive
Development Code Update by April 2024;
annually review Development Code and
revise as needed; produce brochures and
make information available on the City’s
website by December 2024.

Ongoing. The proposed revisions in the draft Development Code is anticipated to be presented to the Stockton City Council for consideration in Summer/Fall 2025. Following the adoption of the Development Code, information and brochures will be made available.

ATTACHMENT B
683

21. Preserve At-Risk Units
Continue to monitor the 392 assisted
units, and if any become at risk, work
with property owners to develop a
strategy to provide assistance to
maintain or replace 392 at-risk units as
affordable to reduce potential for
displacement of tenants and loss of
affordable housing stock in the city.

Ongoing communication with owners,
service providers, and eligible potential
purchasers; work with owners of deedrestricted units on an ongoing basis, in particular at the time of change of
ownership.

Ongoing. During 2024, the city continued to release Notice of Funding Availability (NOFA) processes to provide funding from the U.S. Department of Housing & Urban Development (HUD) for the development of affordable housing, which includes substantial rehabilitation of existing multi-family housing to preserve at-risk units. Staff continue to monitor expiring affordability periods for existing affordable housing and will coordinate with property owners to identify strategies to preserve atrisk units.

22. Housing Rehabilitation
Programs
Assist 300 lower-income units to address
potential displacement, especially in
areas of the city with the poorest
housing conditions as identified during
the windshield survey, including the
Downtown area; areas in close proximity
to agricultural employment opportunities
such as parts of the Weston/Van Buskirk
neighborhood, the Industrial Annex, the
Morada/Holman neighborhood, and the
North Stockton Annex neighborhood; as
well as any areas identified during the
development of the HAP and
Neighborhood Action Plans. Additional
outreach will be targeted in areas with
the highest concentration of children in
single female-headed households,
including parts of the Weston/Van
Buskirk neighborhood, Downtown, and
South Stockton. Of these units, assist 75
units with extremely low-income
households.

Completed study and survey in 2023.

Rehabilitation program is ongoing.

Annually review the availability of
funding opportunities and apply as
opportunities become available.

Ongoing. The study and survey were completed in 2023, and resulted in the creation and adoption of a Slum Blight Area Map for use of HUD funding. Assistance and outreach for rehabilitation is ongoing, and during 2025 targeted outreach will be conducted as part of the Homeowner Rehabilitation Programs in low-income neighborhoods, including those identified in the Neighborhood Action Plans.

23. Code Enforcement
Program
Inspect 2,000 units annually, prioritizing
areas with high potential need for
rehabilitation, including the Downtown
area; as well as areas in close proximity
to agricultural employment opportunities
including parts of the Weston/Van
Buskirk neighborhood, the Industrial
Annex, the Morada/Holman
neighborhood, and the North Stockton
Annex neighborhood; as well as any
areas identified during the development
of the HAP and Neighborhood Action
Plans.

Ongoing Ongoing. There were 24,729 Inspections conducted by the Neighborhood Services Department for 2024. The type of inspections were not readily available to staff.

24. Replacement of
Existing Affordable Units N/A Ongoing Ongoing. Demolition permits are being monitored to ensure state compliance.

25. Continue to Support
Organizations Assisting
Homeless Persons
Annually, assist up to 2,000 unduplicated
homeless persons; and 1,000
households at-risk of homelessness with
limited-term rental assistance or utility
payments. Target outreach and
distribute information about these
programs in the downtown area, close to
existing homeless services. As part of
this, increase the number of board and
care or other types of residential or
transitional care facilities for vulnerable
populations by 300-500 beds. Prioritize
new residential or transitional care
facilities for vulnerable populations in
higher-opportunity areas or areas in
close proximity to services, including the
Midtown, Trinity/Northwest Stockton,
Pacific Avenue/Lincoln Village, Eight
Mile/Bear Creek, and Morada/Holman
neighborhoods.

Apply for funding annually and provide
funding to housing providers to fund onsite case managers and other support services annually. Provide operating
support for organizations that provide
basic services, outreach, and
engagement annually. Provide financial
support for the Coordinated Entry
system annually through at least 2027.

Ongoing. The city continues to coordinate with homeless-support organizations to provide resources and funding for ongoing operations, as well as to support the development of housing for homeless persons. During 2024, the city provided funding for the Coordinated Entry System and Homeless Management Information System (HMIS).

26. Continue to Assist the
Disabled in Community
Development Block Grant
Project Areas
Provide mobility assistance home-repair
grants for 120 low-income individuals
and households including those with
special needs including disabilities, in
Stockton, including rental units. Of these
individuals or households, provide
mobility assistance for home-repair
grants for 5 extremely low-income
individuals or households including
those with special needs including
disabilities.

Annually, contingent upon CDBG funding Ongoing. During 2024, the city completed two (2) homeowner rehabilitation projects for seniors with mobility issues, and continues to explore avenues to provide affordable housing funding for the construction of new housing for a full spectrum of population types, including disabled individuals.

27. Universal Design
100 housing units with universal design
features to facilitate accessibility for
persons with disabilities and seniors;
encouraging at least five (5) of these
units to be located near transit stations
and services.

Make updates as part of the
Comprehensive Development Code
update by April 2024
Ongoing. A separate amendment to the Development Code will be proposed following the adoption of the draft Development Code that is anticipated to be presented to the Stockton City Council for consideration in Summer/Fall 2025. The separate amendment will be presented to for consideration by the end of 2025.

ATTACHMENT B
684

28. Assist Farm Workers
and other Members of the
Workforce
Assist other organizations in developing
at least 500 units or housing for
farmworkers in Stockton or in the
County during the planning period,
including 300 in high and moderate
resource areas in relative proximity to
agricultural employment opportunities,
including parts of the Weston/Van
Buskirk neighborhood, the Industrial
Annex, the Morada/Holman
neighborhood, and the North Stockton
Annex neighborhood.

Meet twice per year to explore
opportunities for farmworker housing
Ongoing and will require outreach to community groups in 2025. Although the city does not have any farms, the city updated their HOME preference policies in 2024 to include farmworker housing. There are active farmworker housing projects under development that are viable candidates for future HUD funding awarded through future NOFA processes, pending applications.

29. Addressing the Needs
of Those with Disabilities
By revising its Development Code to
remove development constraints, the
City will facilitate the development of 300
units for households with a household
member who has a disability.

Revise the Reasonable Accommodation
procedure including the findings as part
of the Comprehensive Development Code
Update by April 2024. Prepare public
information on Reasonable
Accommodations by June 2024. Continue
to partner with the Valley Mountain
Regional Center and review the materials
on the City website annually starting in
2024 and update as needed after each
annual review.

This revision is proposed in the draft Development Code anticipated to go before the Stockton City Council for consideration in Summer/Fall 2025. The handout for the public will need to be completed following the adoption of the draft Development Code. The city’s annual NOFA process offers opportunities for affordable housing developers to apply for funding for projects serving disabled individuals.

30. Practices to
Affirmatively Further Fair
Housing
See individual strategies bulleted in the
program language at left with specific
targets.

Refer to each strategy in this
Affirmatively Furthering Fair Housing
(AFFH) program for specific time frames.
• Implement the following strategies to affirmatively further fair housing in coordination with the efforts of this action:
o Strategies to facilitate housing mobility/expand affordable housing in high opportunity areas: Programs 6, 12, 14, 15, 17, 26, 27 (Ongoing) o Strategies to reduce or prevent displacement/place-based revitalization strategies: Programs 4, 7, 9, 16, 18, 21, 22, 23, 24, 31 (Ongoing) • The City shall continue to provide funds from its CDBG Program to San Joaquin County Fair Housing to provide fair housing counseling and education and outreach efforts to City residents. In addition to providing contact information for San Joaquin Fair Housing on the City's website (under the Housing Division), the City shall continue to make referrals to Fair Housing as issues/cases come to the City's attention. The City shall also work with Fair Housing to periodically review and update fair housing brochures that are provided to the public and posted on the City's website. The City shall distribute fair housing information at City offices, the library, community centers, and other community facilities. These actions are ongoing. Review fair housing materials every two years starting in 2024. Update materials as needed every two years following the review. The City will assist at least 200 residents annually through the complaint referral process. If fewer than 200 residents use the process, provide assistance to all that do. (Ongoing) • The City will educate selected staff in the Community Development, Economic Development, City Attorney, and City Manager departments on responding to complaints received regarding potential claims of housing discrimination and provide these selected personnel with a handout detailing the process for someone with a complaint and the agency that should be contacted regarding a claim: Legal Aid of Northern California. The City will also maintain a log of all complaints received. The initial training of City staff will start in 2024; with updated training occurring two (2) years thereafter to align with changes to state law. (Ongoing) • The City will also work with San Joaquin Fair Housing to provide additional training to housing providers to prevent discriminatory actions and behaviors. If the City does not have enough staff capacity to conduct housing audits in order to reduce displacement risk, particularly in lower opportunity areas of Stockton, the City will pursue audit or other strategies to proactively identify discrimination such as contracting with a fair housing provider or outside housing consultant to provide assistance, by March 2025, and then later reviewed annually. The steps in the process would be the City issuing a Request for Proposals for partnership with an external consultant to provide the service of conducting housing audits annually. The City would either renew the contract or seek a new fair housing provider to provide the same service on a yearly basis. (Ongoing) • The City shall review and update its Analysis of Impediments to Fair Housing Report every five years. The next update is scheduled to happen in 2025. (Ongoing) • Should the City conduct a new General Plan Update within the housing cycle, the elements will be updated to strengthen existing AFFH and equity programs as well as a new disadvantaged community inventory for city and unincorporated areas within the City’s sphere of influence. (Ongoing)
• The City shall post its Annual Housing Element Progress Reports to HCD on the City website annually in the Spring after the report is completed. (To be completed in 2025 after the approval of HCD.) • The City will implement multilingual communication and outreach strategies for City-funded affordable housing developments as follows. To increase access to City housing programs and remove barriers to homeownership, provide translation services in the most common languages spoken locally at all public meetings by July 2024 and ensure all public materials are translated and made available. (Ongoing) • In order to assist with the high percentage of households living in overcrowded situations including farmworkers, the City will encourage rental developments to add additional bedrooms and will prioritize the use of HOME funds for rental projects, provided that some of the units have three or more bedrooms with a goal of approving 100 units with three or more bedrooms. Additionally, when feasible, expand the City’s preapproved ADU plans to include ADU plans with 3 bedrooms. (Ongoing) • when feasible, expand ADU pre-approved plans to include ADU plans with 3-bedrooms. (Ongoing) • Incentivize on-site child care in mixed use and multifamily development, particularly for projects in areas with higher proportions of single parent households, which can make childcare easier to access for single-female headed households and potentially lower their cost of living. (Ongoing) • The City shall explore best practices for Rent Stabilization and Just Cause Evictions to increase the certainty and fairness within the residential rental market in the City and work to prevent displacement, in addition to the protection granted by California Civil Code Section 1946.2. Exploration may include efforts associated with the Housing Action Plan or additional outreach efforts specific to the topic presented. Specifically, steps in this process will include market/feasibility analysis (complete by December 2024), a community workshop and presentation of findings and recommendations related to the city implementing Just Cause Eviction and Rent Stabilization regulations to the Planning Commission after the exploration/evaluation is complete (hold workshop and Planning Commission meeting by June 2025). (Ongoing) • The City will remove and/or repeal any known program or ordinance residing within SMC Title 16 (development Code) that does not comply with current State Housing Element Law by December 2025, and annually assess if additional amendments are needed to respond to future changes to state law. This includes the voluntary “Crime Free Multi-Housing Program” to discourage criminal activities at multifamily housing facilities. (Ongoing)

31. Environmental Health
and Access to Resources
See individual strategies bulleted in the
program language at left with specific
targets.

Refer to each strategy in this program for
specific time frames.
• Update the City’s Parks and Recreation Master Plan and continue to enhance existing parks, open space, and tree plantings and provide new parks and open space in these areas to improve environmental health. Facilitate safe pedestrian and bicycle access to parks or open spaces to reduce environmental health disparities across the city. Implement this objective during the CIP process. (The City's Park and Recreation Master Plan will be published in Fall 2025 and will be presented to the City Council afterwards).
• Work with Caltrans to reduce regional air quality impacts associated with regional transportation facilities. The City will meet with Caltrans annually, as feasible, to identify options for air quality improvements and coordinate action implementation. (Ongoing)
• Add performance measures to the City’s Development Code for inventory sites located within 1000 feet of freeways and/or existing facilities that contribute to low air quality conditions as part of the Comprehensive Development Code Update, by April 2024. (A separate amendment to the Development Code will be proposed following the adoption of the draft Development Code that is anticipated to be presented to the Stockton City Council for consideration in Summer/Fall 2025. The separate amendment will be presented to for consideration by the end of 2025.) • Partner with regional transit agencies and other organizations to address transit needs of those with disabilities including non-fixed-route transportation including paratransit, dial-a-ride, reduced-fare taxis or volunteer driver programs. (Ongoing)
• Use place-based strategies to increase active transportation facilities in Downtown and South Stockton to reduce dependence on automobiles and enhance safe connections to existing pedestrian and bicycle routes. The City will identify at least two active transportation projects in these areas of the city by June 2025. The City has completed a sidewalk survey as part of the Neighborhood Action Plans (in Little Manila/Gleason Park, Cabral Station and South Airport Way areas) to identify gaps and where repairs are needed. As part of implementation of the Neighborhood Action Plans, the city plans to pursue funding to assist property owners with repair and installation of sidewalks in the three study areas. Funding could come from local sources such as the City’s General Fund or State or federal sources such as the Safe Routes to School Program. (Ongoing) • Meet with school district representatives by June 2025 to analyze whether housing security poses a barrier, focusing on disadvantaged areas with low education domain scores, including the Port and Mount Diablo Waterfront, Midtown, South Stockton, East Stockton, Industrial Annex, Mariposa Lakes, and Weston/Van Buskirk neighborhoods. Work with the school districts to assist in securing grant funding for teacher recruitment and retention bonuses, classroom materials, and other incentives for teachers to facilitate positive learning environments citywide. (Ongoing) • Require developers to provide local schools with information about initial lease-ups of new affordable housing units within the school catchment area, and ask school leadership to distribute this information to families in their school. (Ongoing)
• Implement new commercial/industrial zoning in South Stockton (details are provided in Program 17) (Ongoing) • Implement new industrial zoning standards and processing for reviewing existing and future industrial projects adjacent to residential uses (details are provided in Program 16) (Ongoing)

32. Removal of Racially
Restrictive Covenants
Remove all racially restrictive covenants
from Stockton City-owned properties by
December 2025 and assist in the removal
of all known privately owned properties
by the end of the 6th housing cycle.

Advertise County program starting in
2025; launch website and social media
campaigns to support property owners
to voluntarily remove these covenants
by December 2025, with ongoing
reminders in City publications and at
City events. Support County
enforcement of this State requirement as
appropriate through City actions. Work
with at least 20 property owners annually
to support their efforts to remove
restrictions from their deeds.

Remove all covenants on City-owned
properties by December 2025; launch
informational campaign between June
and December 2025; encouragement of
removal of covenants from private
properties is ongoing.

Ongoing. During 2025, city staff will conduct extensive research on the existence (if any) of racially restrictive covenants from city-owned properties, with a target date of having them removed by December 2025.

ATTACHMENT B
685

33. Disperse Sites Suitable
for Lower Income Housing
to Affirmatively Further
Fair Housing
1,193 additional lower income units on
sites in relatively higher income and
higher resource areas in neighborhoods
such as Trinity/Northwest Stockton,
Eight Mile Rd/Bear Creek, and Northeast
of Morada Lane.

Make sites available including any
needed General Plan or zoning code
revisions, by December 31, 2026.

Completed and ongoing. Staff completed an additional land capacity inventory as part of the Housing Action Plan that went beyond the RHNA analysis of just vacant and approved projects. Staff identified more underutilized land and county land for residential as part of that analysis. As high density residential currently allows 30 du/ac net, the city has more than enough capacity for high density housing for lower income residents in the north Stockton area.

ATTACHMENT B
686
Jurisdiction Stockton ANNUAL ELEMENT PROGRESS REPORT
Reporting Period 2024 (Jan. 1 - Dec. 31) Housing Element Implementation Planning Period 6th Cycle 12/31/2023 - 12/31/2031
Description of Commercial
Development Bonus
Commercial Development Bonus
Date Approved
3 4
APN Street Address Project Name+ Local Jurisdiction
Tracking ID+
Very Low
Income
Low
Income
Moderate
Income
Above Moderate
Income
Description of Commercial
Development Bonus
Commercial Development Bonus
Date Approved
Summary Row: Start Data Entry Below
Units Constructed as Part of Agreement
Commercial Development Bonus Approved pursuant to GC Section 65915.7 Table E
Note: "+" indicates an optional field
Project Identifier
1 2
Cells in grey contain auto-calculation
formulas
(CCR Title 25 §6202)
Annual Progress Report January 2020

ATTACHMENT B
687
Jurisdiction Stockton ANNUAL ELEMENT PROGRESS REPORT Note: "+" indicates an optional field Reporting Period 2024 (Jan. 1 - Dec. 31) Housing Element Implementation Cells in grey contain auto-calculation formulas Planning Period 6th Cycle 12/31/2023 - 12/31/2031
The description should adequately document how each
unit complies with subsection (c) of Government Code
Section 65583.1+.

For detailed reporting requirements, see the chcklist
here:

Extremely LowIncome+ Very Low-Income+ Low-Income+ TOTAL UNITS+Extremely LowIncome+Very LowIncome+ Low-Income+ TOTAL UNITS+ https://www.hcd.ca.gov/communitydevelopment/docs/adequate-sites-checklist.pdf Rehabilitation Activity
Preservation of Units At-Risk
Acquisition of Units
Mobilehome Park Preservation
Total Units by Income
Table F
Please note this table is optional: The jurisdiction can use this table to report units that have been substantially rehabilitated, converted from non-affordable to affordable by acquisition, and preserved, including mobilehome park preservation, consistent with the standards set forth in Government Code section 65583.1, subdivision (c). Please note, motel, hotel, hostel rooms or other structures that are converted from non-residential to residential units pursuant to Government Code section 65583.1(c)(1)(D) are considered net-new housing units and must be reported in Table A2 and not reported in Table F.

Activity Type
Units that Do Not Count Towards RHNA+
Listed for Informational Purposes Only
Units that Count Towards RHNA +
Note - Because the statutory requirements severely limit what can be counted, please contact HCD at [email protected] and we will unlock the form which enable you to populate these fields.

Units Rehabilitated, Preserved and Acquired for Alternative Adequate Sites pursuant to Government Code section 65583.1(c) Annual Progress Report January 2020

ATTACHMENT B
688
Jurisdiction Stockton ANNUAL ELEMENT PROGRESS REPORT Note: "+" indicates an optional field
Reporting Period 2024 (Jan. 1 - Dec. 31) Housing Element Implementation Cells in grey contain auto-calculation formulas Planning Period 6th Cycle 12/31/2023 - 12/31/2031
Notes
2 3 6
Prior APN+ Current APN Street Address Project Name+
Local
Jurisdiction
Tracking ID
Unit Category
(2 to 4,5+)
Tenure
R=Renter
Very LowIncome Deed
Restricted
Very LowIncome Non
Deed
Restricted
Low- Income Deed
Restricted
Low- Income
Non Deed
Restricted
Moderate- Income
Deed Restricted
ModerateIncome Non Deed
Restricted
Above
ModerateIncome
Total Moderate Income Units
Converted from Above
Moderate
Date Converted Notes
Summary Row: Start Data Entry Below 0 0 0 0 0 0 0 0
Table F2
Above Moderate Income Units Converted to Moderate Income Pursuant to Government Code section 65400.2 For up to 25 percent of a jurisdiction’s moderate-income regional housing need allocation, the planning agency may include the number of units in an existing multifamily building that were converted to deed-restricted rental housing for moderate-income households by the imposition of affordability covenants and restrictions for the unit. Before adding information to this table, please ensure housing developments meet the requirements described in Government Code 65400.2(b). 5 Project Identifier Unit Types
1 4
Affordability by Household Incomes After Conversion Units credited toward Moderate Income RHNA

ATTACHMENT B
689
Jurisdiction Stockton
Reporting Period 2024 (Jan. 1 - Dec. 31)
Planning Period 6th Cycle 12/31/2023 - 12/31/2031 ANNUAL ELEMENT PROGRESS REPORT Housing Element Implementation
2 3 4
APN Street Address Project Name+ Local Jurisdiction
Tracking ID+
Realistic Capacity
Identified in the
Housing Element
Entity to whom the site
transferred Intended Use for Site
1 Summary Row: Start Data Entry Below
Note: "+" indicates an optional field
Cells in grey contain auto-calculation
formulas
Table G
Locally Owned Lands Included in the Housing Element Sites Inventory that have been sold, leased, or otherwise disposed of Project Identifier
NOTE: This table must only be filled out if the housing element sites inventory contains a site which is or was owned by the reporting jurisdiction, and has been sold, leased, or otherwise disposed of during the reporting year.

ATTACHMENT B
690
Jurisdiction Stockton Note: "+" indicates an optional field Reporting Period 2024
(Jan. 1 - Dec.
31)
Cells in grey contain auto-calculation
formulas
Designation Size Notes
1 2 3 4 5 6 7
APN Street Address/Intersection Existing Use Number of
Units
Surplus
Designation
Parcel Size (in
acres) Notes
145-270-09 705 W Weber Avenue Vacant Surplus Land 3.08
These properties, known collectively
as "South Pointe," were approved by
City Council as part of a Development
& Disposition Agreement on February
6, 2024. The properties will be
disposed upon successful
environmental remediation.
145-270-10 Weber Avenue Vacant Surplus Land 0.29
These properties, known collectively
as "South Pointe," were approved by
City Council as part of a Development
& Disposition Agreement on February
6, 2024. The properties will be
disposed upon successful
environmental remediation.
145-270-06 833 W Weber Avenue Vacant Surplus Land 3.73
These properties, known collectively
as "South Pointe," were approved by
City Council as part of a Development
& Disposition Agreement on February
6, 2024. The properties will be
disposed upon successful
environmental remediation.
145-190-03 855 W Weber Avenue Vacant Surplus Land 1.97
These properties, known collectively
as "South Pointe," were approved by
City Council as part of a Development
& Disposition Agreement on February
6, 2024. The properties will be
disposed upon successful
environmental remediation.
149-261-20 411 S Stanislaus St Vacant Surplus Land 1.66 149-095-02 530 E Lafayette St Vacant Surplus Land 0.11
149-095-03 534 E Lafayette St Vacant Surplus Land 0.09
149-095-04 536 E Lafayette St Vacant Surplus Land 0.14
077-490-01 1450 W Hammer Lane Vacant Surplus Land 0.21
149-180-21 725 E Main St Vacant Surplus Land 0.34
137-410-09 Miner's Levee Vacant Surplus Land 2
151-310-12 E Scotts Avenue & E Taylor Street Vacant Exempt Surplus Land 0.17
Site declared surplus, but will need
subsequent action due to the ROW
designation. City will coordinate with
HCD on the appropriate process to
dispose of the site as Exempt Surplus
Land.
155-300-02 Diamond Street & E Worth Street Vacant Exempt Surplus Land 0.09
Previous water well site. City Council
approved the sale of this exempt
surplus land on 10/1/24, with final
sale still pending.
169-020-11 1501 S Airport Way Vacant Surplus Land 2.53
169-030-13 1516 S Union Street Vacant Surplus Land 0.68 169-020-02 1805 S Airport Way Vacant Surplus Land 0.34
169-040-09 1814 S Union St Vacant Surplus Land 0.18
175-260-34 Lincoln Street & Horton Avenue Vacant Surplus Land 0.06 175-070-08 Lincoln Street & Horton Avenue Vacant Surplus Land 2.73 169-077-03 2135 S Airport Way Vacant Surplus Land 0.33
157-030-13 2849 E Lafayette St Vacant Surplus Land 0.19 072-020-55 9602 Thornton Road Vacant Excess 5.16
Property has been determined to be
Excess, pending Council approval to
be declared Surplus.

NOTE: This table must contain an invenory of ALL
surplus/excess lands the reporting jurisdiction owns
Summary Row: Start Data Entry Below
Parcel Identifier

ANNUAL ELEMENT PROGRESS REPORT
Housing Element Implementation
Table H
Locally Owned Surplus Sites
For San Joaquin County jurisdictions, please format the APN's as follows:999-999-999-999

ATTACHMENT B
691
Jurisdiction Stockton ANNUAL ELEMENT PROGRESS REPORT
Reporting Period 2024 (Jan. 1 - Dec. 31) Housing Element Implementation Planning Period 6th Cycle 12/31/2023 - 12/31/2031
Project Type Date
Units (Beds/Student
Capacity) Granted
Density Bonus
Notes
2 3 5 6
APN Street Address Project Name+ Local Jurisdiction
Tracking ID+
Unit Category
(SH - Student Housing) Date Very Low- Income
Deed Restricted
Very Low- Income
Non Deed
Restricted
Low- Income Deed
Restricted
Low- Income Non
Deed Restricted
Moderate- Income
Deed Restricted
Moderate- Income
Non Deed
Restricted
Above
ModerateIncome
Total Additional Beds
Created Due to Density
Bonus
Notes
Summary Row: Start Data Entry Below
Note: "+" indicates an optional field
Cells in grey contain auto-calculation formulas
Table J
Student housing development for lower income students for which was granted a density bonus pursuant to subparagraph (F) of paragraph (1) of subdivision (b) of Section 65915 Project Identifier Units (Beds/Student Capacity) Approved 1 4
NOTE: STUDENT HOUSING WITH DENSITY BONUS ONLY. This
table only needs to be completed if there were student housing projects WITH a density bonus approved pursuant to Government Code65915(b)(1)(F)
Annual Progress Report January 2020

ATTACHMENT B
692
Jurisdiction Stockton ANNUAL ELEMENT PROGRESS REPORT
Reporting Period 2024 (Jan. 1 - Dec. 31)
Planning Period 6th Cycle 12/31/2023 - 12/31/2031
No
Table K
Tenent Preference Policy
Local governments are required to inform HCD about any local tenant preference ordinance the local government maintains when the jurisdiction submits their annual progress report on housing approvals and production, per Government Code 7061 (SB 649, 2022, Cortese).

Effective January 1, 2023, local governments adopting a tenant preference are required to create a webpage on their internet website containing authorizing local ordinance and supporting materials, no more than 90 days after the ordinance becomes operational.

Does the Jurisdiction have a local tenant preference policy? If the jurisdiction has a local tenant preference policy, provide a link to the jurisdiction's webpage containing authorizing local ordinance and supporting materials.

Notes

ATTACHMENT B
693
Jurisdiction Stockton
Reporting Year 2024 (Jan. 1 - Dec. 31)
Total Award Amount Total award amount is auto-populated based on amounts entered in rows 15-26.

Task $ Amount Awarded $ Cumulative Reimbursement
Requested
Other
Funding Notes
Zoning Map and Code Amendments $100,000.00 $175,023.00 Other Funded by SB2, LEAP, and City.

Housing Element Update $150,000.00 $100,000.00 Other
LEAP and City funded. Housing Element Approved in
July 2024 with Resolution 2024-07-09-1601. Online
Link:
(https://stockton.granicus.com/MinutesViewer.php?vie
w_id=48&clip_id=8721).

Housing Action Plan $200,000.00 $250,000.00 Other
LEAP and City funded. Action Plans were adopted in
November 2024 (Resolution 2024-11-19-1504. Online
Link:
https://stockton.granicus.com/MinutesViewer.php?vie
w_id=48&clip_id=8863).

Mobility and Vehicle Miles Traveled
(VMT) analysis $100,000.00 $69,830.00 Other LEAP and City funded.

Displacement Study $100,000.00 $50,000.00 None
Part of the Action Plan analysis. Action Plans were
adopted in November 2024 (Resolution 2024-11-19-
1504. Online Link:
https://stockton.granicus.com/MinutesViewer.php?vie
w_id=48&clip_id=8863).

Analysis of Infrastructure
Dificencies $100,000.00 $20,125.00 Other
LEAP, REAP, and City funds. Efforts tied to Housing
Action Plan and Neighborhood Action Plans. Action
Plans were adopted in November 2024 (Resolution
2024-11-19-1504. Online Link:
https://stockton.granicus.com/MinutesViewer.php?vie
w_id=48&clip_id=8863).

Summary of entitlements, building permits, and certificates of occupancy (auto-populated from Table A2) Current Year
Deed Restricted 51
Non-Deed Restricted 202
Deed Restricted 0
Non-Deed Restricted 31
Deed Restricted 0
Non-Deed Restricted 16
537
837
Current Year
Deed Restricted 51
Non-Deed Restricted 202
Deed Restricted 0
Non-Deed Restricted 31
Deed Restricted 0
Non-Deed Restricted 16
537
837
Current Year
Deed Restricted 0
Non-Deed Restricted 0
Deed Restricted 0
Non-Deed Restricted 4
Deed Restricted 0
Non-Deed Restricted 5
260
269

ANNUAL ELEMENT PROGRESS REPORT
Local Early Action Planning (LEAP) Reporting
(CCR Title 25 §6202)
Completed
Please update the status of the proposed uses listed in the entity’s application for funding and the corresponding impact on housing within the region or jurisdiction, as applicable, categorized based on the eligible uses specified in Section 50515.02 or 50515.03, as applicable.
$ 750,000.00
Task Status
Completed
Completed
Completed
Completed
Completed
Total Units
Certificate of Occupancy Issued by Affordability Summary Income Level
Very Low
Low
Moderate
Above Moderate
Moderate
Above Moderate
Total Units
Completed Entitlement Issued by Affordability Summary
Income Level
Very Low
Low
Moderate
Above Moderate
Total Units
Building Permits Issued by Affordability Summary
Income Level
Very Low
Low

ATTACHMENT B
694
2024 ANNUAL PROGRESS REPORTS

FOR THE
ENVISION STOCKTON 2040 GENERAL PLAN
AND
6TH CYCLE HOUSING ELEMENT
Agenda Item 16.2
City Council Meeting
March 18, 2025
695
• Cities are required to have a General
Plan and a Housing Element
• The General Plan is the long-range policy
document for the City of Stockton
• The Housing Element is a component of
the General Plan & updated every 8 years
• The recently updated Stockton 2023-2031
Housing Element was certified by the
State and approved by City Council in
2024 (6th Housing Cycle)
Background
6962
Purpose
3 2023-2031
Housing Element
APR
Envision Stockton
2040 General Plan
APR
Submit to State
by April 1st
[Required by Government Code Section 65400 & 65700]
Annual Progress Reports (APR)
697
4 Policies
Guide staff, Planning
Commission, and City
Council in their review of
land development
projects and in decision
making.

Actions
Measure, procedure, or
technique intended to
implement one or more
policies to help reach a
specified General Plan
goal.
2040 General Plan
698
Housing Element & Regional Housing Needs Allocation (RHNA) 5 Housing Element Cycle
State of
CA
SJCOG
City
State
of CA
City

1. Every 8 years, the State
(HCD) provides SJCOG
with regional RHNA
determination

2. SJCOG allocated
the regional RHNA
(52,719 units)
between the
unincorporated county
and city jurisdictions

3. The City adopts a
Housing Element

4. The Housing
Element is
Certified by
the state

5. The City reports
annual progress (i.e.

APRs) in meeting the
2023-2031 Stockton
RHNA allocation of
(12,673 units)
699
Housing Element: Objectives
6 Housing Needs
(existing/future)
Available Land
(RHNA)
Constraints
700
7 Outreach workshops and stakeholder
presentations for the draft Development Code
and Design Standards overhauls
New 2023-2031
Housing Element
certified by State and
adopted by City Council
Housing Action Plan &
Neighborhood Action
Plans approved by
City Council
2024 General Plan Accomplishments
Public Facility Fee (PFF)
Nexus Study underway
Updated Safety Element
adopted by City Council
701
2024 Housing Element Progress
• New 2023-2031 Housing Element Certified by
State and adopted by City Council
• The Stockton Housing Action Plan was adopted,
that includes three separate Neighborhood Action
Plans
• Approved construction plans for affordable housing
projects: St. Mary’s Pathways and Park Center
Apartments
• Launched Expanded Accessory Dwelling Unit
(ADU) pre-approval program
702 8
2024 Permits
• 837 new housing units
o 253 very low-income
units
o 31 low-income units
o 16 moderate income
units
o 537 above-moderate
income units
9 • 52 Accessory Dwelling
Units (ADUs)
• Utilization of Stockton’s
pre-approved plans
703
10 • 837 new housing units in 2024
• Need to average 1,584 new units per year
• Past (5th Cycle) Housing Element, Stockton averaged 545 units per year
• Market ultimately drives development
RHNA Compliance: Current Housing Cycle
704
Staff recommends the City Council:
• Accept the 2024 Annual Reports, and
• Authorize the City Manager to submit
the Reports to the State by April 1, 2025
Recommendation
70511
City of Stockton
Legislation Text
File #: 25-0142, Version: 1
PUBLIC HEARING TO APPROVE A RESOLUTION ADOPTING THE 2024 EASTERN SAN

JOAQUIN GROUNDWATER SUSTAINABILITY PLAN AMENDMENT

RECOMMENDATION
It is recommended that the City Council, acting as the City of Stockton Groundwater Sustainability Agency, conduct a Public Hearing to accept and respond to public comment on the 2024 Groundwater Sustainability Plan amendment for the Eastern San Joaquin Subbasin. At the conclusion of the Public Hearing, it is recommended that the City Council approve a resolution to:

1. Approve and adopt the 2024 Groundwater Sustainability Plan Amendment for the Eastern San Joaquin Subbasin.

2. Authorize the Eastern San Joaquin Groundwater Authority, its staff, and its consultants, to take such other actions as may be reasonably necessary to submit the 2024 Groundwater Sustainability Plan Amendment and the 2025 Periodic Evaluation to the Department of Water Resources and implement the plan.

3. Authorize the Municipal Utilities Department to work in collaboration with other local agencies to implement the projects and programs developed in the 2024 Groundwater Sustainability Plan in compliance with the Sustainable Groundwater Management Act.

It is also recommended that the City Manager be authorized to take appropriate actions to carry out the purpose and intent of this resolution.

Summary
The Municipal Utilities Department (MUD) is comprised of three enterprise funds including Water, Wastewater, and Stormwater Utilities. The Water Utility provides drinking water service to the northern and southern regions of the Stockton Metropolitan Area, with the California Water Service Company and San Joaquin County serving the central region. The Delta Water Treatment Plant (DWTP) began operation in May 2012, providing up to 30 million gallons per day of treated surface water from the Sacramento-San Joaquin River Delta and Mokelumne River. Stockton’s other water supplies are derived from the Calaveras and Stanislaus Rivers through a water supply agreement with the Stockton East Water District and a number of groundwater wells.

The City has a vested interest in the sustainable management of the local groundwater subbasin and became a Groundwater Sustainability Agency (GSA) in 2015. As a GSA, the City is responsible for groundwater management, monitoring, and other activities within its jurisdiction to help control and protect the City groundwater supply and improve the sustainability of the subbasin.

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File #: 25-0142, Version: 1
The City and 15 other member GSAs form the Eastern San Joaquin Groundwater Authority (GWA) and are responsible for preparing the Groundwater Sustainability Plan (GSP) for the Eastern San Joaquin Subbasin. In December 2019, the GWA created the first GSP and approved and adopted the plan in compliance with SGMA.

Staff recommends that the City Council, acting under its authority as a GSA, approve and adopt the new 2024 GSP Amendment for the Eastern San Joaquin Subbasin (Exhibit 1 to the Resolution) and authorize the GWA to take actions as may be reasonably necessary to submit the 2025 Periodic Evaluation (Exhibit 2 to the Resolution) for the Eastern San Joaquin Subbasin to the State Department of Water Resources (DWR).

DISCUSSION
Background
Groundwater wells are important to the City as a supply source, particularly in times of drought when local rivers experience decreased flows.

The State of California passed the Sustainable Groundwater Management Act (SGMA) in 2014, which established a statewide framework for groundwater management through Groundwater Sustainability Agencies. Section 10723 of California Water Code states that “the following agencies created by statute to manage groundwater shall be deemed the exclusive local agencies within their respective statutory boundaries with powers to become a GSA.” The City of Stockton became an approved GSA in 2015.

As described in DWR Bulletin 118, of the 515 groundwater basins in California, 127 are categorized as medium or high priority basins. The Eastern San Joaquin Subbasin is listed as a “high priority” basin. The SGMA requires medium and high priority basins to develop groundwater sustainability agencies (GSAs), develop groundwater sustainability plans (GSPs) by 2020 and manage groundwater for long-term sustainability. On behalf of the City of Stockton and the other 15 member agencies, the GWA submitted the 2020 Eastern San Joaquin GSP to the DWR on January 29, 2020.

The GSP must provide, among other items, detailed physical descriptions, monitoring programs, and management provisions, and describe interaction with other plans, such as the Stockton General Plan. The GSP must also indicate a path to groundwater sustainability within 20 years of adoption. A sustainable groundwater basin, as described in the SGMA, includes no groundwater depletions that have significant and unreasonable adverse impacts on beneficial uses or users of groundwater.

Present Situation
The SGMA requires evaluations of GSPs every five years that include responses to recommended corrective actions from DWR should they remain outstanding. The City coordinated the preparation of the 2024 GSP Amendment with the GWA and all other Eastern San Joaquin subbasin GSAs to respond to DWR’s Recommended Corrective Actions as set forth in their 2023 determination letter. In addition, the GWA agencies also coordinated the preparation of the first periodic evaluation (2025 Periodic Evaluation) of the GSP to be submitted to DWR.

As described in the 2024 GSP Amendment and 2025 Periodic Evaluation, the Eastern San Joaquin City of Stockton Page 2 of 3 Printed on 3/13/2025
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File #: 25-0142, Version: 1
Groundwater Authority continues to make significant progress toward achieving the sustainability goals outlined in the original 2020 Groundwater Sustainability Plan and the 2022 Revised GSP including the following:
· Most monitoring wells show groundwater levels at or above their measurable objectives with interim milestones being met throughout the subbasin.
· Groundwater quality in the subbasin remains suitable to support beneficial uses and is expected to surpass measurable objectives with no exceedances of minimum thresholds observed.
· Groundwater quality should meet measurable objectives or minimum thresholds over the next five years.

On July 24, 2024, GWA noticed the intent to adopt the 2024 GSP Amendment pursuant to California Water Code Section 10728.4. From October 1, 2024, through October 31, 2024, a public review period welcomed comments from members of the public on the 2024 GSP Amendment.

In addition, the Water Advisory Group and Council Water Committee reviewed and recommended the submission of the 2024 GSP Amendment for the Eastern San Joaquin Subbasin to DWR at their respective meetings held on October 2, 2024 and October 10, 2024. In addition, this public hearing was publicly noticed in The Record on March 5, 2025, and March 12, 2025.

Staff recommends that the City Council, acting under its authority as the City of Stockton GSA, adopt the 2024 GSP Amendment for the Eastern San Joaquin Subbasin and authorize the GWA, its consultants, and the Plan Manager to take all necessary actions to submit the 2025 Periodic Evaluation of the subbasin to DWR.

FINANCIAL SUMMARY
Funds for this planning activity are available in the FY 2024-25 Budget in the Water Fund - Administration Division.

Future financial requirements for GSP compliance and implementation under the SGMA will be reviewed and subject to City Council approval during the annual budget development process.

There is no impact to the General Fund, or any other unrestricted fund, from this action.

City of Stockton Page 3 of 3 Printed on 3/13/2025
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Resolution No.

STOCKTON CITY COUNCIL
RESOLUTION ADOPTING THE 2024 EASTERN SAN JOAQUIN GROUNDWATER

SUSTAINABILITY PLAN AMENDMENT
In August 2014, the California Legislature passed, and in September 2014, the Governor signed the Sustainable Groundwater Management Act of 2014 (SGMA) “to provide local groundwater sustainability agencies with the authority, technical and financial assistance necessary to sustainably manage groundwater (Wat. Code, § 10720, (d)); and
The City of Stockton is a Groundwater Sustainability Agency (GSA) and a member of the Eastern San Joaquin Groundwater Authority (GWA) comprised of 16 local agencies and formed to develop a groundwater sustainability plan (GSP) and coordinate sustainable groundwater management in the Eastern San Joaquin Subbasin (Subbasin). Water Code section 10723.6(i) of SB 1168 states that “the following agencies created by statute to manage groundwater shall be deemed the exclusive local agencies within their respective statutory boundaries with powers to become a Groundwater Sustainability Agency (GSA)”; and
The SGMA requires sustainable groundwater management through the development and implementation of GSPs. The GWA submitted the first Eastern San Joaquin Subbasin GSP to the Department of Water Resources (DWR) on January 29, 2020; and
By letter dated July 6, 2023, DWR approved the amended GSP, as revised in 2022, and included a list of eight “Recommended Corrective Actions” for the GSAs to consider for the first Periodic Evaluation of the GSP as required by SGMA; and The City coordinated with the GWA and all other GSAs overlying the Eastern San Joaquin Subbasin to prepare the 2024 Eastern San Joaquin Groundwater Sustainability Plan Amendment to respond to the DWR Recommended Corrective Actions and to prepare the first five-year Periodic Evaluation of the GSP to be submitted to DWR; and
The City acknowledges and has taken action to implement projects to help meet necessary goals and management actions during the 20-year GSP implementation period to achieve and maintain sustainable groundwater conditions in the subbasin by or before 2040; and
The City acknowledges a Program for Dry Domestic Well Mitigation was adopted by the Eastern San Joaquin Groundwater Authority on September 11, 2024, with said 709
resolution being included in Appendix 3-J of the amendments to the GSP; and The City commits to the development and adoption of a Demand Management Program by December 31, 2027, as described in Chapter 6 of the amendments to the GSP; and
The City coordinated with the GWA and all other GSAs overlying the Eastern San Joaquin Subbasin to prepare the Subbasin 2025 Periodic Evaluation to be submitted to DWR; and
On July 24, 2024, the GWA noticed the intent to adopt the 2024 GSP Amendment pursuant to Water Code section 10728.4. From October 1, 2024, through October 31, 2024, a public review period welcomed comments on the 2024 GSP Amendment; and
The Water Advisory Group and the Council Water Committee reviewed and recommended the submission of the 2024 GSP Amendment for the Eastern San Joaquin Subbasin to DWR on October 2, 2024 and October 10, 2024, respectively. In addition, a public hearing was publicly noticed in The Record on March 5, 2025, and March 12, 2025; and
Staff recommends that the City Council, acting as the City of Stockton Groundwater Sustainability Agency, adopt the 2024 GSP for the Eastern San Joaquin Subbasin and authorize the GWA to take actions as may be reasonably necessary to submit the GSP Amendment to the DWR; now, therefore,

BE IT RESOLVED BY THE CITY COUNCIL OF THE CITY OF STOCKTON, AS FOLLOWS:

1. The 2024 GSP Amendment is hereby approved and adopted, a copy of which is attached as Exhibit 1 and incorporated by this reference.

2. The GWA, its staff, and its consultants are authorized to take such other actions as may be necessary to submit to DWR the 2024 GSP Amendment and the 2025 Periodic Evaluation, a copy of which is attached as Exhibit 2.

3. The Municipal Utilities Department is authorized to work in collaboration with other local agencies to implement the projects and programs developed in the 2024 GSP Amendment in compliance with the Sustainable Groundwater Management Act. //
//
//
//
//
//
//
710

4. The City Manager is hereby authorized to take whatever actions are necessary and appropriate to carry out the purpose and intent of this Resolution.

PASSED, APPROVED, and ADOPTED March 18, 2025 .

CHRISTINA FUGAZI
Mayor of the City of Stockton
ATTEST:

KATHERINE ROLAND, CMC, CPMC
City Clerk of the City of Stockton
711
Eastern San Joaquin Groundwater
Subbasin
2024 Groundwater
Sustainability Plan Amendment:

Agency Information, Plan Area,
and Communication
Prepared by:

November 2024
EXHIBIT 1
712
This page is intentionally left blank.

EXHIBIT 1
713
2024 Groundwater Sustainability Plan Amendment i
Agency Information, Plan Area, and Communication November 2024

TABLE OF CONTENTS
SECTION PAGE NO.

EXECUTIVE SUMMARY .........................................................................................................................................ES-1

1. AGENCY INFORMATION, PLAN AREA, AND COMMUNICATION...............................................................1-1

1.1 Introduction and Agency Information.....................................................................................................1-1

1.1.1 Purpose of the Groundwater Sustainability Plan .................................................................1-1

1.1.2 Sustainability Goal...............................................................................................................1-2

1.1.3 Contact Information .............................................................................................................1-2

1.1.4 Agency Information..............................................................................................................1-3

1.1.5 GSP Organization..............................................................................................................1-10

1.2 Plan Area.............................................................................................................................................1-10

1.2.1 Description of Plan Area ....................................................................................................1-11

1.2.2 Water Resources Monitoring and Management Programs................................................1-23

1.2.3 Land Use Elements or Topic Categories of Applicable General Plans ..............................1-35

1.2.4 Additional GSP Elements ..................................................................................................1-41

1.3 Notice and Communication..................................................................................................................1-43

1.3.1 Beneficial Uses and Users in the Basin.............................................................................1-43

1.3.2 List of Public Meetings Where the 2024 GSP was Discussed...........................................1-44

1.3.3 Decision-Making Process ..................................................................................................1-45

1.3.4 Opportunities for Public Engagement and How Public Input was Used.............................1-45

1.3.5 Inter-basin Coordination ....................................................................................................1-56

1.3.6 Notice of Intent to Adopt the GSP......................................................................................1-56

2. BASIN SETTING .............................................................................................................................................2-1

2.1 Hydrogeologic Conceptual Model..........................................................................................................2-1

2.1.1 Data Compilation .................................................................................................................2-1

2.1.2 Regional Geologic and Structural Setting..........................................................................2-10

2.1.3 Geologic History ................................................................................................................2-11

2.1.4 Near-Surface Conditions ...................................................................................................2-11

2.1.5 Geologic Formations and Stratigraphy ..............................................................................2-27

2.1.6 Faults and Structural Features...........................................................................................2-35

2.1.7 Geologic Cross-Sections ...................................................................................................2-38

2.1.8 Basin Boundaries...............................................................................................................2-49

2.1.9 Principal Aquifer.................................................................................................................2-50

2.1.10 HCM Data Gaps ................................................................................................................2-71

2.2 Historical Groundwater Conditions ......................................................................................................2-72

2.2.1 Groundwater Elevation ......................................................................................................2-72

2.2.2 Groundwater Storage ........................................................................................................2-91

2.2.3 Seawater Intrusion.............................................................................................................2-93

2.2.4 Conditions as of 2019: Groundwater Quality .....................................................................2-93

2.2.5 Conditions in 2019: Land Subsidence .............................................................................2-115

2.2.6 Conditions in 2019: Interconnected Surface Water Systems...........................................2-116

2.2.7 Conditions in 2019: Groundwater-Dependent Ecosystems .............................................2-119

2.3 Current Groundwater Conditions .......................................................................................................2-127

2.3.1 Groundwater Elevation ....................................................................................................2-127

2.3.2 Groundwater Storage ......................................................................................................2-132

2.3.3 Seawater Intrusion...........................................................................................................2-133

2.3.4 Groundwater Quality........................................................................................................2-137 EXHIBIT 1
714
2024 Groundwater Sustainability Plan Amendment ii
Agency Information, Plan Area, and Communication November 2024

2.3.5 Land Subsidence.............................................................................................................2-140

2.3.6 Interconnected Surface Water Systems ..........................................................................2-148

2.3.7 Groundwater-Dependent Ecosystems .............................................................................2-154

2.4 Water Budgets...................................................................................................................................2-156

2.4.1 Water Budget Background Information............................................................................2-156

2.4.2 Identification of Hydrologic Periods..................................................................................2-158

2.4.3 Use of the ESJWRM and Associated Data in Water Budget Development .....................2-159

2.4.4 Water Budget Definitions and Assumptions.....................................................................2-160

2.4.5 Water Budget Estimates ..................................................................................................2-166

2.4.6 Projected Water Budget with Demand Reduction Estimates (ESJWRM PCBL-DR Version

3.0) ..................................................................................................................................2-189

2.4.7 Projected Water Budget with Climate Change and Demand Reduction Estimates (ESJWRM PCBL-CC-DR Version 3.0) ..............................................................................................2-195

2.4.8 Projected Water Budget with PMAs Estimates (ESJWRM PCBL-PMA Version 3.0).......2-200

2.4.9 Projected Water Budget with Climate Change and PMAs Estimates (ESJWRM PCBL-CCPMA Version 3.0).............................................................................................................2-208

3. SUSTAINABLE MANAGEMENT CRITERIA...................................................................................................3-1

3.1 Sustainability Goal.................................................................................................................................3-1

3.2 Updates to Sustainability INdicators ......................................................................................................3-3

3.3 Revised Sustainability Indicators ...........................................................................................................3-3

3.3.1 Chronic Lowering of Groundwater Levels............................................................................3-3

3.3.2 Reduction in Groundwater Storage....................................................................................3-13

3.3.3 Degraded Water Quality ....................................................................................................3-16

3.3.4 Seawater Intrusion.............................................................................................................3-26

3.3.5 Land Subsidence...............................................................................................................3-26

3.3.6 Depletions of Interconnected Surface Water .....................................................................3-31

4. MONITORING NETWORKS............................................................................................................................4-1

4.1 Monitoring Network for Chronic Lowering of Groundwater Levels.........................................................4-1

4.1.1 Representative Monitoring Network for Groundwater Levels...............................................4-1

4.1.2 Monitoring Protocols for Groundwater Level Data Collection and Monitoring......................4-5

4.1.3 Frequency and Timing of Groundwater Level Monitoring ....................................................4-6

4.1.4 Spatial Density of Groundwater Level Monitoring Network..................................................4-6

4.2 Monitoring Network for Reduction in Groundwater Storage ..................................................................4-7

4.3 Monitoring Networks for Degraded Water Quality .................................................................................4-7

4.3.1 Representative Monitoring Network for Groundwater Quality..............................................4-8

4.3.2 Monitoring Protocols for Groundwater Quality Data Collection and Monitoring .................4-10

4.3.3 Frequency and Timing of Groundwater Quality Monitoring................................................4-11

4.3.4 Spatial Density of Groundwater Quality Monitoring Wells..................................................4-11

4.4 Monitoring Network for Seawater Intrusion..........................................................................................4-11

4.5 Monitoring Network for Land Subsidence............................................................................................4-12

4.5.1 Representative Monitoring Network for Subsidence..........................................................4-12

4.5.2 Monitoring Protocols for Subsidence Data Collection and Monitoring ...............................4-14

4.5.3 Frequency and Timing of Subsidence Monitoring..............................................................4-14

4.5.4 Spatial Density of Subsidence Monitoring Stations ...........................................................4-14

4.6 Monitoring Network for Depletions of Interconnected Surface Waters ................................................4-15

4.6.1 Representative Monitoring Network for Interconnected Surface Water.............................4-15

4.6.2 Monitoring Protocols for Interconnected Surface Water Data Collection and Monitoring ..4-18

4.6.3 Frequency and Timing of Interconnected Surface Water Monitoring.................................4-18

4.6.4 Spatial Density of Interconnected Surface Water Monitoring Network ..............................4-18 EXHIBIT 1
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4.7 Data Gaps ...........................................................................................................................................4-18

4.7.1 Groundwater Level Data Gaps ..........................................................................................4-18

4.7.2 Groundwater Quality Data Gaps........................................................................................4-18

4.7.3 Interconnected Surface Water System Data Gaps ............................................................4-19

4.7.4 Groundwater-Dependent Ecosystem Data Gaps...............................................................4-19

4.7.5 Plan to Fill Data Gaps........................................................................................................4-19

5. DATA MANAGEMENT SYSTEM ....................................................................................................................5-1

5.1 Overview of the Eastern San Joaquin Subbasin Data Management System........................................5-1

5.2 Functionality of the Data Management System.....................................................................................5-1

5.2.1 User and Data Access Permissions.....................................................................................5-2

5.2.2 Data Entry and Validation ....................................................................................................5-3

5.2.3 Visualization and Analysis ...................................................................................................5-5

5.2.4 Query and Reporting ...........................................................................................................5-7

5.3 Data Included in the Data Management System ...................................................................................5-7

6. PROJECTS AND MANAGEMENT ACTIONS.................................................................................................6-1

6.1 Projects, Management Actions, and Adaptive Management Strategies ................................................6-1

6.2 Projects..................................................................................................................................................6-1

6.2.1 Project Identification ............................................................................................................6-1

6.2.2 Project Implementation ........................................................................................................6-2

6.2.3 List of Projects .....................................................................................................................6-2

6.2.4 Category A Projects...........................................................................................................6-13

6.2.5 Category B Projects...........................................................................................................6-28

6.2.6 Mokelumne River Loss Study ............................................................................................6-54

6.2.7 Notification Process ...........................................................................................................6-54

6.3 Management Actions...........................................................................................................................6-54

6.4 Adaptive Management Strategies........................................................................................................6-56

6.5 Simulation of Projects and Management Actions in Projected Water Budget .....................................6-58

6.6 Potential Available Funding Mechanisms ............................................................................................6-58

7. PLAN IMPLEMENTATION..............................................................................................................................7-1

7.1 Implementation Schedule ......................................................................................................................7-1

7.2 Implementation Costs............................................................................................................................7-6

7.3 Monitoring and Reporting ......................................................................................................................7-8

7.3.1 Monitoring............................................................................................................................7-8

7.3.2 Developing Annual Reports .................................................................................................7-9

7.3.3 Data Management System Updates..................................................................................7-10

7.4 Data Collection and Analysis...............................................................................................................7-10

7.4.1 Model Refinements............................................................................................................7-10

7.4.2 Construction of Additional Wells ........................................................................................7-11

7.4.3 Data Gaps and Uncertainties.............................................................................................7-11

7.5 Administrative Actions .........................................................................................................................7-11

7.6 Developing 5-Year Periodic Evaluation Reports..................................................................................7-11

7.6.1 New Information.................................................................................................................7-11

7.6.2 Sustainability Evaluation....................................................................................................7-12

7.6.3 Status of Projects and Management Actions .....................................................................7-12

7.6.4 Basin Setting Based on New Information or Changes in Water Use .................................7-12

7.6.5 Monitoring Network Description.........................................................................................7-12

7.6.6 Legal or Enforcement Actions............................................................................................7-12

7.6.7 Coordination ......................................................................................................................7-12 EXHIBIT 1
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7.6.8 Other Information...............................................................................................................7-12

7.7 Outreach..............................................................................................................................................7-13

7.8 Implementing GSP-Related Projects and Management Actions .........................................................7-13

7.9 GSP Implementation Funding..............................................................................................................7-18

8. REFERENCES...............................................................................................................................................8-20 EXHIBIT 1
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2024 Groundwater Sustainability Plan Amendment v
Agency Information, Plan Area, and Communication November 2024 Appendices
Appendix 1-A Eastern San Joaquin Groundwater Authority JPA Agreement and Bylaws Appendix 1-B Legal Authority of Eastern San Joaquin GSAs Appendix 1-C Agency Resolutions to Become GSAs
Appendix 1-D DWR Preparation Checklist
Appendix 1-E Community Water Systems
Appendix 1-F Relevant General Plan Goals and Policies
Appendix 1-G Freshwater Species in the Eastern San Joaquin Subbasin Appendix 1-H 2024 Eastern San Joaquin Subbasin Communication and Engagement Plan Update Appendix 1-I Public Comments Received
Appendix 1-J Response to Public Comments
Appendix 1-K Notice of Intent to Adopt the 2024 GSP Amendment Appendix 2-A Eastern San Joaquin Water Resources Model (ESJWRM) Report Appendix 2-B Eastern San Joaquin Water Resources Model (ESJWRM) Report Version 2.0 Update (2022) Appendix 2-C Eastern San Joaquin Water Resources Model (ESJWRM) Report Version 3.0 Update (2024) Appendix 3-A Consultation Initiation Letter from the California Department of Water Resources to the Eastern San Joaquin Plan Administrator entitled “Eastern San Joaquin Subbasin – 2020 Groundwater Sustainability Plan”, dated November 18, 2021
Appendix 3-B Determination Letter from DWR to ESJ Entitled “Approved Determination of the Revised Groundwater Sustainability Plan Submitted for the San Joaquin Valley – Eastern San Joaquin Subbasin” Dated July 6, 2023
Appendix 3-C Technical Memorandum No. 1 – Groundwater Levels Appendix 3-D Technical Memorandum No. 2 – Subsidence
Appendix 3-E Technical Memorandum No. 4 – Water Budgets and Groundwater Storage Appendix 3-F Technical Memorandum No. 3 – Groundwater Quality Appendix 3-G Technical Memorandum No. 5 – Interconnected Surface Water Appendix 3-H Supplemental Data for Groundwater Level Minimum Thresholds Appendix 3-I Hydrographs Showing Groundwater Level Minimum Thresholds and Measurable Objectives Appendix 3-J Domestic Well Mitigation Program
Appendix 5-A List of DMS Data Types
Appendix 6-A Additional Projects Added to GSP
Appendix 6-B Technical Memorandum No. 6 – Demand Management Program EXHIBIT 1
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2024 Groundwater Sustainability Plan Amendment vi
Agency Information, Plan Area, and Communication November 2024 Tables
Table 1-1: Minimum Depth of Seal Below Ground Surface for Wells in San Joaquin County.................................. 1-39 Table 1-2: Minimum Depth of Seal Below Ground Surface for Wells in Calaveras County...................................... 1-40 Table 1-3: Minimum Depth of Seal Below Ground Surface for Wells in Stanislaus County ..................................... 1-41 Table 1-4: Groundwater Sustainability Workgroup Interests (Collected During Development of 2020 GSP) .......... 1-46 Table 1-5: Stakeholder Database Summary ............................................................................................................ 1-54 Table 2-1: Eastern San Joaquin Subbasin Watershed Details ................................................................................ 2-16 Table 2-2: Generalized Stratigraphic Column, Formation Descriptions, and Water-Bearing Properties.................. 2-31 Table 2-3: Production Zone Capacities.................................................................................................................... 2-59 Table 2-4: Wells within Water-Bearing Zones.......................................................................................................... 2-60 Table 2-5: Summary of Chloride Data by Decade.................................................................................................... 2-97 Table 2-6: Summary of Chloride Data by Depth (1940s-2010s) .............................................................................. 2-98 Table 2-7: Summary of TDS Data by Depth (2015-2018)...................................................................................... 2-103 Table 2-8: Nitrate as N Concentrations by Decade................................................................................................ 2-105 Table 2-9: Arsenic Concentrations by Decade....................................................................................................... 2-110 Table 2-10: MCLs for Common Petroleum Hydrocarbons and MTBE ................................................................... 2-114 Table 2-11: MCLs for Common Synthetic Organic Constituents............................................................................ 2-115 Table 2-12: Chloride Concentrations after 2015 .................................................................................................... 2-136 Table 2-13: Summary of Water Budget Assumptions (Historical, Current, and Projected Periods)....................... 2-161 Table 2-14: Average Annual Water Budget for Revised ESJWRM (Version 3.0) – Stream System (AF/year)...... 2-169 Table 2-15: Average Annual Water Budget for Revised ESJWRM – Land Surface System (AF/year).................. 2-171 Table 2-16: Average Annual Water Budget for Revised ESJWRM – Groundwater System (AF/year) .................. 2-173 Table 2-17: Average Annual Values for Key Components of Historical Water Budget by Year Type.................... 2-178 Table 2-18: Average Annual Values for Key Components of Projected Water Budget by Year Type.................... 2-185 Table 2-19: Average Annual Values for Key Components of Projected Conditions with Climate Change Water Budget by Year Type ............................................................................................................................. 2-189 Table 2-20: ESJ Subbasin Land and Water Use Budget Annual Average Comparison Between PCBL Version 3.0 and PCBL-DR Version 3.0......................................................................................................... 2-191 Table 2-21: ESJ Subbasin Hydrologic Groundwater Budget Annual Average Comparison Between PCBL Version 3.0 and PCBL-DR Version 3.0......................................................................................................... 2-194 Table 2-22: ESJ Subbasin Land and Water Use Budget Annual Average Comparison Between PCBL-CC Version 3.0 and PCBL-CC-DR Version 3.0 .................................................................................................. 2-196 Table 2-23: ESJ Subbasin Hydrologic Groundwater Budget Annual Average Comparison Between the PCBL-CC and the PCBL-CC-DR Version 3.0 ................................................................................................... 2-199 Table 2-24: Summary of ESJWRM Category A Projects Surface Water Deliveries............................................... 2-202 Table 2-25: ESJ Subbasin Land and Water Use Budget Annual Average Comparison Between PCBL Version 3.0 and PCBL-PMA Version 3.0...................................................................................................... 2-204 Table 2-26: ESJ Hydrologic Groundwater Budget Annual Average Comparison Between the PCBL (Version 3.0) and the PCBL-PMA (Version 3.0)..................................................................................................... 2-207 Table 2-27: ESJ Subbasin Land and Water Use Budget Annual Average Comparison Between PCBL-CC Version 3.0 and PCBL-CC-PMA Version 3.0................................................................................................ 2-210 Table 2-28: ESJ Hydrologic Groundwater Budget Annual Average Comparison Between the PCBL-CC and the PCBL-CC-PMA Version 3.0....................................................................................................... 2-212 Table 3-1: Minimum Thresholds for Chronic Lowering of Groundwater Levels.......................................................... 3-9 Table 3-2: Measurable Objective for Chronic Lowering of Groundwater Levels ...................................................... 3-10 Table 3-3: Interim Milestones for Chronic Lowering of Groundwater Levels............................................................ 3-13 Table 3-4: Salinity Tolerances of Major Subbasin Crops ......................................................................................... 3-20 Table 3-5: Measurable Objective and Interim Milestones for Degraded Water Quality for Total Dissolved Solids (mg/L TDS)............................................................................................................................................ 3-24 Table 3-6: Measurable Objective and Interim Milestones for Degraded Water Quality for Chloride (mg/L chloride) 3-25 EXHIBIT 1
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2024 Groundwater Sustainability Plan Amendment vii
Agency Information, Plan Area, and Communication November 2024 Table 3-7: Minimum Thresholds for Interconnected Surface Water......................................................................... 3-32 Table 3-8: Measurable Objectives and Interim Milestones for Interconnected Surface Water................................. 3-35 Table 4-1: Representative Monitoring Wells for Groundwater Levels ........................................................................ 4-2 Table 4-2: DWR Monitoring Well Density Recommendations.................................................................................... 4-7 Table 4-3: Groundwater Level Monitoring Network Density....................................................................................... 4-7 Table 4-4: Representative Monitoring Network Wells for Water Quality .................................................................... 4-9 Table 4-5: Historical Groundwater Quality Monitoring Frequency at Identified Local Water Quality Wells .............. 4-11 Table 4-6: Groundwater Quality Monitoring Network Density .................................................................................. 4-11 Table 4-7: Representative Monitoring Network for Inelastic Land Subsidence........................................................ 4-13 Table 4-8: Representative Monitoring Wells for Interconnected Surface Water....................................................... 4-15 Table 4-9: Considerations for Well Selection and Well Installation .......................................................................... 4-22 Table 5-1: Data Management System User Types .................................................................................................... 5-2 Table 5-2: Data Collection Site Information ............................................................................................................... 5-3 Table 5-3: Data Types and Their Associated Parameters Configured in the DMS .................................................... 5-8 Table 5-4: Sources of Data Included in the Data Management System..................................................................... 5-9 Table 6-1: List of SGMA Projects............................................................................................................................... 6-4 Table 6-2: Overview of Project Types and Available Funding Mechanisms............................................................. 6-59 Table 7-1: GSP Schedule for Implementation 2020 to 2040...................................................................................... 7-2 Table 7-2: Costs to GSAs and GSP Implementation Costs ....................................................................................... 7-6 Table 7-3: Funding Mechanisms for Proposed Projects and Management Actions................................................. 7-14 Table 7-4: Potential Funding Sources for GSP Implementation............................................................................... 7-18 EXHIBIT 1
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2024 Groundwater Sustainability Plan Amendment viii
Agency Information, Plan Area, and Communication November 2024 Figures
Figure ES- 1: GSP Plan Area within the San Joaquin Valley.........................................................................................1 Figure ES- 2: Basin Setting............................................................................................................................................3 Figure ES- 3: GAMA Water Quality Sampling Locations ..............................................................................................4 Figure ES- 4: Sample Relationship Between Minimum Threshold and Measurable Objective ......................................6 Figure ES- 5: Subbasin-Wide Total Groundwater Pumping and Offsets Required to Achieve Sustainability ................7 Figure ES- 6: Monitoring Sites .......................................................................................................................................8 Figure ES- 8: Opti DMS Screenshot ..............................................................................................................................9 Figure ES- 9: Typical DMS Data Display .......................................................................................................................9 Figure 1-1: Interconnected Planning and Modeling Efforts for Water Resource Protection ....................................... 1-2 Figure 1-2: Plan Manager and Agency Contact Information ..................................................................................... 1-2 Figure 1-3: Eastern San Joaquin Groundwater Sustainability Agencies.................................................................... 1-4 Figure 1-4: Placement within the San Joaquin Valley Groundwater Basin .............................................................. 1-12 Figure 1-5: Neighboring Groundwater Subbasins.................................................................................................... 1-13 Figure 1-6: Underlying and Surrounding Counties................................................................................................... 1-14 Figure 1-7: City Boundaries ..................................................................................................................................... 1-15 Figure 1-8: Disadvantaged Communities (DACs) .................................................................................................... 1-16 Figure 1-9: Land Use ............................................................................................................................................... 1-17 Figure 1-10: Land Use by Crop Type....................................................................................................................... 1-18 Figure 1-11: US Fish and Wildlife Service, California State Parks, and California Department of Fish and Wildlife Boundaries .................................................................................................................................. 1-20 Figure 1-12: Density of Domestic Wells per Square Mile......................................................................................... 1-21 Figure 1-13: Density of Public Wells per Square Mile.............................................................................................. 1-22 Figure 1-14: Density of Production Wells per Square Mile....................................................................................... 1-23 Figure 1-15: Eastern San Joaquin GMP Region Setting.......................................................................................... 1-31 Figure 1-16: Locations of Groundwater Recharge Projects Prior to SGMA Implementation.................................... 1-35 Figure 2-1: Depth of All Wells in Water Data Library.................................................................................................. 2-3 Figure 2-2: Depth Distribution of Wells in Water Data Library.................................................................................... 2-4 Figure 2-3: GAMA Monitoring Well Network .............................................................................................................. 2-5 Figure 2-4: Number of Chloride Measurements Taken at GAMA Monitoring Sites (2005-2017) ............................... 2-6 Figure 2-5: AEM Flight Lines across ESJ Subbasin................................................................................................... 2-9 Figure 2-6: Geologic Time Scale.............................................................................................................................. 2-10 Figure 2-7: Topography............................................................................................................................................ 2-13 Figure 2-8: Major Hydrologic Features..................................................................................................................... 2-14 Figure 2-9: Eastern San Joaquin Subbasin Watersheds ......................................................................................... 2-17 Figure 2-2-10: Soil Depositional Areas .................................................................................................................... 2-18 Figure 2-11: Hydrologic Soil Groups ........................................................................................................................ 2-20 Figure 2-12: Occurrence of Hardpan within the Eastern San Joaquin Subbasin ..................................................... 2-21 Figure 2-13: Areal Extents of Alluvial Fans, Interfans, and Pre-Modesto Formations.............................................. 2-23 Figure 2-14: Existing Areas of Groundwater Recharge (ESJWRM Version 3.0)...................................................... 2-25 Figure 2-15: Average Percent Coarse Fraction in Near-Surface Materials.............................................................. 2-26 Figure 2-16: Potential Recharge Areas.................................................................................................................... 2-27 Figure 2-17: Generalized Geologic Section and Eastern San Joaquin Subbasin Setting ........................................ 2-28 Figure 2-18: Geologic Map....................................................................................................................................... 2-29 Figure 2-19: Faults and Structural Features ............................................................................................................ 2-36 Figure 2-20: Base of Fresh Water Elevation and Stockton Fault ............................................................................. 2-37 Figure 2-21: Cross-Section, by Formation, Location Map........................................................................................ 2-39 Figure 2-22: Hydrogeologic Cross-sections A-A’ and B-B’....................................................................................... 2-40 Figure 2-23: Hydrogeologic Cross-sections C-C’ and D-D’...................................................................................... 2-41 Figure 2-24: Hydrogeologic Cross- section E-E’ ...................................................................................................... 2-42 EXHIBIT 1
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2024 Groundwater Sustainability Plan Amendment ix
Agency Information, Plan Area, and Communication November 2024 Figure 2-25: Cross-Section, by Percent Coarseness, Location Map ....................................................................... 2-43 Figure 2-26: Percent Coarse Cross-Section F-F’..................................................................................................... 2-44 Figure 2-27: Percent Coarse Cross-Section G-G’.................................................................................................... 2-45 Figure 2-28: Percent Coarse Cross-Section H-H’ .................................................................................................... 2-46 Figure 2-29: Percent Coarse Cross-section I-I’........................................................................................................ 2-47 Figure 2-30: Bottom Elevation of Water-Bearing Zones (Shallow)........................................................................... 2-52 Figure 2-31: Bottom Elevation of Water-Bearing Zones (Deep and Intermediate)................................................... 2-53 Figure 2-32: Elevation of Base of Continental Deposits........................................................................................... 2-56 Figure 2-33: Sand and Gravel Isopach Map ............................................................................................................ 2-58 Figure 2-34: Total Number of Cation/Anion Measurements in the Eastern San Joaquin Subbasin......................... 2-63 Figure 2-35: Trilinear Diagrams ............................................................................................................................... 2-64 Figure 2-36: TDS Annual Variation .......................................................................................................................... 2-65 Figure 2-37: TDS Concentrations in 2017................................................................................................................ 2-66 Figure 2-38: Chloride Annual Variation .................................................................................................................... 2-67 Figure 2-39: Chloride Concentrations in 2017.......................................................................................................... 2-68 Figure 2-40: Sulfate Annual Variation ...................................................................................................................... 2-69 Figure 2-41: Sulfate Concentrations in 2017............................................................................................................ 2-70 Figure 2-42: Hydrographs of Selected Wells............................................................................................................ 2-74 Figure 2-43: Summary of Groundwater Elevation Data, 1940-2018 ........................................................................ 2-76 Figure 2-44: Precipitation Stations ........................................................................................................................... 2-77 Figure 2-45: First Quarter 2017 Groundwater Elevation .......................................................................................... 2-79 Figure 2-46: Fourth Quarter 2017 Groundwater Levels ........................................................................................... 2-80 Figure 2-47: Map of Nested and/or Clustered Well Sites (as of 2020 GSP Development) ...................................... 2-82 Figure 2-48: Nested Well Hydrographs: CCWD 004-006 (as of 2020 GSP Development)...................................... 2-83 Figure 2-49: Nested Well Hydrographs: CCWD 010-012 (as of 2020 GSP Development)...................................... 2-83 Figure 2-50: Nested Well Hydrographs: Sperry Well (as of 2020 GSP Development)............................................. 2-84 Figure 2-51: Nested Well Hydrographs: Swenson Golf Course (as of 2020 GSP Development) ............................ 2-84 Figure 2-52: Nested Well Hydrographs: STK-1 (as of 2020 GSP Development)..................................................... 2-85 Figure 2-53: Nested Well Hydrographs: STK-2 (as of 2020 GSP Development)..................................................... 2-85 Figure 2-54: Nested Well Hydrographs: STK-4 (as of 2020 GSP Development)..................................................... 2-86 Figure 2-55: Nested Well Hydrographs: STK-5 (as of 2020 GSP Development)..................................................... 2-86 Figure 2-56: Nested Well Hydrographs: STK-6 (as of 2020 GSP Development)..................................................... 2-87 Figure 2-57: Nested Well Hydrographs: STK-7 (as of 2020 GSP Development)..................................................... 2-87 Figure 2-58: Nested Well Hydrographs: Lodi MW-21 (as of 2020 GSP Development)............................................ 2-88 Figure 2-59: Nested Well Hydrographs: Lodi MW-24 (as of 2020 GSP Development)............................................ 2-88 Figure 2-60: Nested Well Hydrographs: Lodi MW-25 (as of 2020 GSP Development)............................................ 2-89 Figure 2-61: Nested Well Hydrographs: Lodi SMW-1 (as of 2020 GSP Development) ........................................... 2-89 Figure 2-62: Nested Well Hydrographs: Lodi WMW-1 (as of 2020 GSP Development) .......................................... 2-90 Figure 2-63: Nested Well Hydrographs: Lodi WMW-2 (as of 2020 GSP Development) .......................................... 2-90 Figure 2-64: Historical Modeled Change in Storage ................................................................................................ 2-91 Figure 2-65: Historical Modeled Change in Annual Storage with Water Use and Year Type .................................. 2-92 Figure 2-66: Maximum Chloride Concentration Greater Than 250 mg/L (1940s-2010s) ......................................... 2-95 Figure 2-67: Maximum Chloride Concentration Above 250 mg/L by Decade .......................................................... 2-96 Figure 2-68: Maximum Chloride Concentration Above 250 mg/L by Well Depth (1940s-2010s)............................. 2-99 Figure 2-69: Maximum TDS Concentrations 2015-2018........................................................................................ 2-101 Figure 2-70: Average TDS Concentrations 2015-2018.......................................................................................... 2-102 Figure 2-71: Maximum TDS Concentrations in Shallow Wells 2015-2018............................................................. 2-103 Figure 2-72: Maximum TDS Concentrations in Deep Wells 2015-2018................................................................. 2-104 Figure 2-73: Nitrate as N Concentrations by Decade............................................................................................. 2-107 Figure 2-74: Arsenic Concentrations by Decade.................................................................................................... 2-109 Figure 2-75: Maximum Arsenic Concentrations 2015-2018................................................................................... 2-110 EXHIBIT 1
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2024 Groundwater Sustainability Plan Amendment x
Agency Information, Plan Area, and Communication November 2024 Figure 2-76: Active Investigation and Remediation Sites as of 2019 ..................................................................... 2-112 Figure 2-77: Active Sites with the Potential to Cause Plumes ............................................................................... 2-113 Figure 2-78: Subsidence (Annual Rate of Vertical Displacement) ......................................................................... 2-116 Figure 2-79: Stream Connectivity to the Groundwater System.............................................................................. 2-118 Figure 2-80: Losing and Gaining Streams ............................................................................................................. 2-119 Figure 2-81: Natural Communities Commonly Associated with Groundwater (NCCAGs) ..................................... 2-121 Figure 2-82: NCCAGs Identified as Data Gap Areas for Future Refinement, Likely to Access Non-groundwater Water Supplies..................................................................................................................................... 2-124 Figure 2-83: Areas Identified as GDEs .................................................................................................................. 2-126 Figure 2-84: Fourth Quarter 2019 Groundwater Elevation (WY 2020)................................................................... 2-128 Figure 2-85: First Quarter 2020 Groundwater Levels (WY 2020) .......................................................................... 2-129 Figure 2-86: Fourth Quarter 2022 Groundwater Elevation (WY 2023)................................................................... 2-130 Figure 2-87: First Quarter 2023 Groundwater Levels (WY 2023) .......................................................................... 2-131 Figure 2-88 : Number of Reported Dry Wells in San Joaquin County between WY 2020-2023 ............................ 2-132 Figure 2-89: Modeled Change in Annual Storage with Water Use and Year Type ................................................ 2-133 Figure 2-90: 2023 Annual Groundwater Pumping.................................................................................................. 2-135 Figure 2-91: Average Chloride Concentrations Post-2015..................................................................................... 2-137 Figure 2-92: Monitoring Frequency for Wells Measuring Total Dissolved Solids ................................................... 2-138 Figure 2-93: Wells with Recent TDS Observations by Well Depth......................................................................... 2-139 Figure 2-94: Maximum Concentrations for Wells Measuring Total Dissolved Solids ............................................. 2-140 Figure 2-95: CGPS Station MTWK – Subsidence Time Series.............................................................................. 2-142 Figure 2-96: CGPS Station P309 – Subsidence Time Series ................................................................................ 2-143 Figure 2-97: CGPS Station CMNC – Subsidence Time Series.............................................................................. 2-144 Figure 2-98: CGPS Station CA1S – Subsidence Time Series ............................................................................... 2-145 Figure 2-99: Subsidence Rates (inches per year) Throughout the Subbasin......................................................... 2-146 Figure 2-100: CGPS Station MTWK: Subsidence Time Series.............................................................................. 2-147 Figure 2-101: CGPS Station CNDR – Time Series of Subsidence and Groundwater Levels ................................ 2-148 Figure 2-102: Stream Reaches in ESJWRM.......................................................................................................... 2-150 Figure 2-103: Surface Waters Connected with the Groundwater System at least 75% of All Months in ESJWRM under Current Conditions .......................................................................................................... 2-151 Figure 2-104: Diagram of Gaining and Losing Connected Streams....................................................................... 2-152 Figure 2-105: Current Conditions Average Annual Stream Gains by Stream Node............................................... 2-154 Figure 2-106: Mapping of Potential Groundwater Dependent Ecosystems............................................................ 2-156 Figure 2-107: Generalized Water Budget Diagram................................................................................................ 2-157 Figure 2-108: 55-Year Historical Precipitation and Cumulative Departure from Mean Precipitation...................... 2-159 Figure 2-109: Historical Average Annual Water Budget – Stream System............................................................ 2-175 Figure 2-110: Historical Average Annual Water Budget – Land Surface System .................................................. 2-176 Figure 2-111: Historical Average Annual Water Budget Estimates – Groundwater System .................................. 2-177 Figure 2-112: Current Average Annual Water Budget Estimates – Stream System.............................................. 2-179 Figure 2-113: Current Average Annual Water Budget Estimates – Land Surface System .................................... 2-180 Figure 2-114: Current Average Annual Water Budget Estimates – Groundwater System..................................... 2-181 Figure 2-115: Projected Average Annual Water Budget Estimates – Stream System........................................... 2-183 Figure 2-116: Projected Average Annual Water Budget Estimates – Land Surface System................................. 2-183 Figure 2-117: Projected Average Annual Water Budget Estimates – Groundwater System.................................. 2-184 Figure 2-118: Projected Average Annual Water Budget Estimates with Climate Change – Stream System......... 2-186 Figure 2-119: Projected Average Annual Water Budget Estimates with Climate Change – Land Surface System2-187 Figure 2-120: Projected Average Annual Water Budget Estimates with Climate Change – Groundwater System 2-188 Figure 2-121: ESJ Subbasin Projected Agricultural Demand in the PCBL-DR Version 3.0 ................................... 2-192 Figure 2-122: ESJ Subbasin Projected Urban Demand in the PCBL-DR Version 3.0 ........................................... 2-192 Figure 2-123: ESJ Subbasin Projected Hydrologic Groundwater Budget in PCBL-DR Version 3.0....................... 2-194 Figure 2-124: ESJ Subbasin Projected Agricultural Demand in the PCBL-CC-DR Version 3.0............................. 2-197 EXHIBIT 1
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2024 Groundwater Sustainability Plan Amendment xi
Agency Information, Plan Area, and Communication November 2024 Figure 2-125: ESJ Subbasin Projected Urban Demand in the PCBL-CC-DR Version 3.0..................................... 2-198 Figure 2-126: ESJ Subbasin Projected Hydrologic Groundwater Budget in the PCBL-CC-DR Version 3.0 .......... 2-200 Figure 2-127: ESJ Subbasin Projected Agricultural Demand in the PCBL-PMA.................................................... 2-205 Figure 2-128: ESJ Subbasin Projected Urban Demand in the PCBL-PMA............................................................ 2-205 Figure 2-129: ESJ Subbasin Projected Hydrologic Groundwater Budget in the PCBL-PMA Version 3.0.............. 2-207 Figure 2-130: ESJ Subbasin Projected Agricultural Demand in the PCBL-CC-PMA Version 3.0 .......................... 2-211 Figure 2-131: ESJ Subbasin Projected Urban Demand in the PCBL-CC-PMA Version 3.0 .................................. 2-211 Figure 2-132: Eastern San Joaquin Subbasin Projected Hydrologic Groundwater Budget in the PCBL-CC-PMA 2-213 Figure 3-1: Sustainable Management Criteria Definitions Graphic (Groundwater Levels Example).......................... 3-2 Figure 3-2: Location of Representative Monitoring Wells for Groundwater Levels .................................................... 3-8 Figure 3-3: Location of Representative Monitoring Wells for Water Quality............................................................. 3-21 Figure 3-4: Defined Critical Infrastructure in the Eastern San Joaquin Subbasin .................................................... 3-28 Figure 3-5: Location of Representative Monitoring Sites for Subsidence................................................................. 3-30 Figure 3-6: Location of Representative Monitoring Sites for Interconnected Surface Water.................................... 3-33 Figure 4-1: Representative Monitoring Network for Groundwater Levels................................................................... 4-5 Figure 4-2: Representative Monitoring Network for Groundwater Quality.................................................................. 4-8 Figure 4-3: Representative Monitoring Network for Inelastic Land Subsidence....................................................... 4-14 Figure 4-4: Representative Monitoring Network for Interconnected Surface Water................................................. 4-17 Figure 4-5: Proposed New Monitoring Well Locations (Shown as Orange Diamonds)............................................ 4-21 Figure 5-1: Opti DMS Screenshot .............................................................................................................................. 5-1 Figure 5-2: DMS Data Entry Tool............................................................................................................................... 5-4 Figure 5-3: Landing Page of Groundwater Portal....................................................................................................... 5-5 Figure 5-4: Progress-At-A-Glance Dashboard ........................................................................................................... 5-6 Figure 5-5: Typical DMS Data Display ....................................................................................................................... 5-6 Figure 6-1: Location of Category A Projects ............................................................................................................ 6-12 Figure 6-2: Location of Category B Projects ............................................................................................................ 6-13 Figure 7-1: GSP Implementation Schedule................................................................................................................ 7-4 EXHIBIT 1
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2024 Groundwater Sustainability Plan Amendment xii
Agency Information, Plan Area, and Communication November 2024 Acronyms
µg/L micrograms per liter
1,2,3-TCP 1,2,3-Trichloropropane
AB Assembly Bill
ACS American Community Survey
AEM Airborne Electromagnetic
AEM airborne electromagnetic survey
AF acre-feet
AF/day acre-feet per day
AF/year acre-feet per year
AMI Advanced Metering Infrastructure
AMI automated metering infrastructure
ASR aquifer storage and recovery
AWMP Agricultural Water Management Plan
B.P. before present
Bay-Delta Plan Water Quality Control Plan for the San Francisco Bay/Sacramento-San Joaquin Delta Estuary
bgs below ground surface
BMP best management practice
BTEX benzene, toluene, ethylbenzene, and xylenes
C&E Plan Communication and Engagement Plan
C2VSim-FG California Central Valley Simulation Model – Fine Grid Cal Water California Water Service Company Stockton District California State Parks California Department of Parks and Recreation CALSIMETAW California Simulation of Evapotranspiration of Applied Water CalTrans California Department of Transportation
CASGEM California Statewide Groundwater Elevation Monitoring CC climate change
CCR California Code of Regulations
CCR Consumer Confidence Report
CCWD Calaveras County Water District
CDEC California Data Exchange Center
CDFW California Department of Fish and Wildlife
CDP census designated place
CDPH California Department of Public Health
CDPR California Department of Pesticide Regulation
CDWA Central Delta Water Agency
CEDEN California Environmental Data Exchange Network
CEQA California Environmental Quality Act
cfs cubic feet per second
CGPF CalSim II Generated Perturbation Factors
CGPS continuous global positioning system
CNRA California Natural Resources Agency
CSJWCD Central San Joaquin Water Conservation District
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Agency Information, Plan Area, and Communication November 2024 CVFPB Central Valley Flood Protection Board
CVRWQCB Central Valley Regional Water Quality Control Board CV-SALTS Central Valley Salinity Alternatives for Long-Term Sustainability CWC California Water Code
CWSRF Clean Water State Revolving Fund
DAC Disadvantaged Community
DBCP 1,2-dibromo-3-chloropropane
DDW Division of Drinking Water
Delta Sacramento-San Joaquin River Delta
DER Department of Environmental Resources
DFW Department of Fish and Wildlife
DMS data management system
DOGGR Division of Oil, Gas, and Geothermal Resources
DPC Delta Protection Commission
DPR Department of Pesticide Regulation
DPW San Joaquin County Department of Public Works
DTSC Department of Toxic Substances Control
DWR Department of Water Resources
Eastside GSA Eastside San Joaquin GSA
EBMUD East Bay Municipal Utility District
EC electrical conductivity
EDB ethylene dibromide
EO Executive Order
EPA Environmental Protection Agency
ERTs Encoder Receiver Transmitters
ESJ Eastern San Joaquin
ESJGWA Eastern San Joaquin Groundwater Authority
ESJGWA Board Eastern San Joaquin Groundwater Authority Board of Directors ESJWRM Eastern San Joaquin Water Resources Model
ETo evapotranspiration
EWMPs efficient water management practices
ft. bgs feet below ground surface
ft/mi feet per mile
GAMA Groundwater Ambient Monitoring and Assessment
GBA Groundwater Basin Authority
GCM global climate model
GDE groundwater dependent ecosystem
GICIMA Groundwater Information Center Interactive Mapping Application GIS Geographic Information System
GMP Groundwater Management Plan
gpd gallons per day
gpm gallons per minute
GSA Groundwater Sustainability Agency
GSP Groundwater Sustainability Plan
GWL groundwater level
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Agency Information, Plan Area, and Communication November 2024 HCM Hydrogeologic Conceptual Model
ICU Program Integrated Conjunctive Use Program
IDW inverse distance weighted
ILRP Irrigated Lands Regulatory Program
InSAR interferometric synthetic aperture radar
IRWM Integrated Regional Water Management
IRWMP Integrated Regional Water Management Plan
ISW interconnected surface water
IWFM Integrated Water Flow Model
JPA Joint Powers Agreement
JPL Jet Propulsion Laboratory
LCSD Lockeford Community Services District
LCWD Linden County Water District
LLNL Lawrence Livermore National Laboratory
LOCA local analogs
MAC Mokelumne-Amador-Calaveras
MAF million acre-feet
MAR managed aquifer recharge
MCL maximum contaminant level
mg/L milligrams per liter
MGD million gallons per day
MHI median household income
MICUP Mokelumne River Integrated Conjunctive Use Program mhos/cm micromhos per centimeter
MO measurable objective
MOA memorandum of agreement
MokeWISE Mokelumne Watershed Interregional Sustainability Evaluation MSL mean sea level
MT minimum threshold
MtBE methyl tertiary-butyl ether
MUD Municipal Utilities Department
MWH Montgomery Watson Harza
NAD 83 North American Datum of 1983
NASA National Aeronautics and Space Administration
NAVD 88 North American Vertical Datum of 1988
NCCAG Natural Communities Commonly Associated with Groundwater NDWA North Delta Water Agency
NEPA National Environmental Policy Act
NGS National Geodetic Survey
NOI Notice of Intent
NPDES National Pollutant Discharge Elimination System
NRCS Natural Resource Conservation Service
NSJWCD North San Joaquin Water Conservation District
NWIS National Water Information System
O&M operations and maintenance
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Agency Information, Plan Area, and Communication November 2024 OES San Joaquin County Office of Emergency Services
OID Oakdale Irrigation District
OSWCR Online System for Well Completion Reports
PCBL Projected Conditions Baseline
PCE perchloroethylene
PDA Protest Dismissal Agreement
pdf portable document format
PFOA perfluorooctantoic acid
PFOS perfluorooctanesulfonic acid
PG&E Pacific Gas and Electric Company
PMA Projects and Management Actions
PMC Project Management Committee
PRISM Precipitation-Elevation Regressions on Independent Slopes Model PS persistent scatter
RCA recommended corrective action
RCD Resource Conservation District
RCP representative climate pathways
RD Reclamation District
RFP request for proposal
RL Reporting Limit
RMN representative monitoring network
RMW representative monitoring well
RWQCB Regional Water Quality Control Board
SAGBI Soil Agricultural Groundwater Banking Index
SAW Stakeholder Advisory Workgroup
SB Senate Bill
SCADA supervisory control and data acquisition
SCWSP South County Water Supply Program
SDACs Severely Disadvantaged Communities
SDWA South Delta Water Agency
SEWD Stockton East Water District
SGM Sustainable Groundwater Management
SGMA Sustainable Groundwater Management Act
SJC San Joaquin County
SJC POC San Joaquin Valley Point of Contacts
SJCFCWCD San Joaquin County Flood Control and Water Conservation District SJV San Joaquin Valley
SMC sustainable management criteria
SMCL secondary maximum contaminant levels
SNMP Salt and Nutrient Management Plan
SOPAC Scripps Orbit and Permanent Array Center
SRA State Recreation Area
SS specific storage
SSJ South San Joaquin
SSJ GSA South San Joaquin GSA
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Agency Information, Plan Area, and Communication November 2024 SSJID South San Joaquin Irrigation District
SVRA State Vehicular Recreation Area
SWRCB State Water Resources Control Board
SWTF Surface Water Treatment Facility
SY specific yield
TAC Technical Advisory Committee
TAFY thousand acre-feet per year
TCE trichloroethene
TDS total dissolved solids
TNC The Nature Conservancy
TSS Technical Support Services
UNAVCO University Navstar Consortium
UNGL University of Nevada Geodetic Laboratory
USACE United States Army Corps of Engineers
USBR United States Bureau of Reclamation
USDA United States Department of Agriculture
USEPA U.S. Environmental Protection Agency
USFWS United States Fish & Wildlife Service
USGS United States Geological Survey
UTM Universal Transverse Mercator
UWMP Urban Water Management Plan
UWMPs Urban Water Management Plans
VFD variable frequency drive
VIC Variable Infiltration Capacity
VOC volatile organic compound
Water Code California Water Code
WDL Water Data Library
WDR Waste Discharge Requirement
WID Woodbridge Irrigation District
WIIN Water Infrastructure Improvements for the Nation
Workgroup Groundwater Sustainability Workgroup
WPCF Water Pollution Control Facility
WRFP Water Recycling Funding Program
WRIMS Water Resource Integrated Modeling System
WY water year
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2024 Groundwater Sustainability Plan Amendment ES-1
Executive Summary November 2024

EXECUTIVE SUMMARY
ES-1. Introduction
In 2014, the California legislature enacted the Sustainable Groundwater Management Act (SGMA) in response to continued overdraft of California’s groundwater resources. The Eastern San Joaquin Groundwater Subbasin (Eastern San Joaquin Subbasin, or Subbasin) is one of 21 basins and subbasins identified by the California Department of Water Resources (DWR) as being in a state of critical overdraft. SGMA requires preparation of a Groundwater Sustainability Plan (GSP) to address measures necessary to attain sustainable conditions in the Subbasin. Within the framework of SGMA, sustainability is generally defined as long-term reliability of the groundwater supply and the absence of undesirable results.

The Eastern San Joaquin Groundwater Authority (ESJGWA) was formed in 2017 in response to SGMA. A Joint Exercise of Powers Agreement establishes the ESJGWA, which is composed of 16 Groundwater Sustainability Agencies (GSAs): Central Delta Water Agency (CDWA), Central San Joaquin Water Conservation District (CSJWCD), City of Lodi, City of Manteca, City of Stockton, Eastside San Joaquin GSA (Eastside GSA) (composed of Calaveras County Water District [CCWD], Calaveras County, Stanislaus County, and Rock Creek Water District), Linden County Water District (LCWD), Lockeford Community Services District (LCSD), North San Joaquin Water Conservation District (NSJWCD), Oakdale Irrigation District (OID), San Joaquin County No. 1, San Joaquin County No. 2 (with participation from California Water Service Company Stockton District [Cal Water]), South Delta Water Agency (SDWA), South San Joaquin GSA (composed of South San Joaquin Irrigation District [SSJID] including Woodward Reservoir, City of Ripon, and City of Escalon), Stockton East Water District (SEWD), and Woodbridge Irrigation District (WID). The ESJGWA is governed by a 16-member Board of Directors (ESJGWA Board), with one representative from each GSA. The Board is guided by a Steering Committee, also with one representative from each GSA, that is tasked with making recommendations to the ESJGWA Board on technical and substantive matters.

SGMA requires development of a GSP that achieves groundwater sustainability in the Subbasin by 2040. The GSP outlines the need to reduce overdraft conditions and has identified 43 projects for potential development that either replace groundwater use (offset) or supplement groundwater supplies (recharge) to meet current and future water demands. Although current analysis indicates that groundwater pumping offsets and/or recharge on the order of 95,000 acre-feet per year (AF/year) may be required to achieve sustainability, additional efforts are needed to confirm the level of pumping offsets and/or recharge required to achieve sustainability. These efforts include collecting additional data and a review of the Subbasin groundwater model, along with other efforts as outlined in the GSP.

To address the requirements prescribed in SGMA and outlined in the GSP Emergency Regulations (2016), the Subbasin GSAs prepard and submitted a Final GSP by the initial January 31, 2020 deadline. On January 28. 2022, the ESJGWA received a Determiniation Letter from DWR. The Letter identified two deficiencies in the Subbasin GSPs which precluded DWR’s approval, as well as potential corrective actions to address each potential deficiency. The Letter initiated consultation between DWR, the Plan Manager, the ESJGWA, and the Subbasin’s GSAs. On July 27, 2022, the GSAs submitted the 2022 Revised GSP to DWR. In a July 6, 2023 Determination Letter, DWR concluded that the GSAs has taken sufficient actions to correct the deficienes identified by DWR and approved the 2022 Revised Plan. This 2023 Determiniation Letter also outlined eight recommended corrective actions that the GSAs could consider addressing during preparation of the first Periodic Evaluation. The ESJGWA determined that a Plan Amendment was required to adequately address the recommended corrective actions.

Critical Dates for the Eastern San Joaquin Subbasin
☒ 2020 By January 31: Submit GSP to DWR
☒ 2025 Evaluate GSP and update if warranted
☐ 2030 Evaluate GSP and update if warranted
☐ 2035 Evaluate GSP and update if warranted
☐ 2040 Achieve sustainability for the Subbasin
Figure ES- 1: GSP Plan Area within
the San Joaquin Valley
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2024 Groundwater Sustainability Plan Amendment ES-2
Executive Summary November 2024
A Public Draft of the 2024 GSP Amendment was prepared and made available for public review and comment on October 1, 2024 for a period of 31 days ending on October 31, 2024. The ESJGWA received numerous comments from the public, reviewed and prepared responses to comments, and revised the Draft 2024 GSP Amendment. This Final 2024 GSP Amendment includes those edits and revisions, as well as edits to address the eight recommended corrective actions in DWR’s 2023 Determination Letter.

ES-2. Plan Area
The ESJGWA’s jurisdictional area is defined by the boundaries of the Eastern San Joaquin Subbasin in DWR’s 2003 Bulletin 118 as updated in 2016 and 2018. The Subbasin underlies the San Joaquin Valley, as shown in Figure ES-1.

ES-3. Outreach Efforts
A stakeholder engagement strategy was developed to enable the interests of beneficial users of groundwater in the Subbasin to be considered. The strategy incorporated bi-monthly Project Management Committee (PMC) meetings, Steering Committee meetings, ESJGWA Board meetings, public meetings, an informational open house event, and information distribution to property owners and residents in the Subbasin.

To support the 5-year Periodic Evaluation of the GSP
and development the 2024 GSP Amendment, the
Steering Committee recommended that the chair of
the ESJGWA form an Ad Hoc Project Management
Committee (PMC). Approved by the Steering
Committee in December 2023, the PMC was
comprised of six GSA volunteers representing the
varied interests in the Subbasin and covering both
urban and agricultural areas. The PMC met bi-monthly
during the GSP Periodic Evaluation and GSP Amendment process, and was tasked with driving the review and update process and coordinating other SGMA implementation efforts, including development of a Domestic Well Mitigation Program, coordination of stakeholder outreach and engagement, and annual and long-term budgeting. PMC members reviewed draft work products and other meeting materials to provide input and direction as needed at the bi-monthly meetings. The PMC was also responsible for recognizing and flagging items requiring discussion and direction from stakeholders, the Steering Committee, and the ESJGWA.

Public Meeting Type Number of
Meetings
ESJGWA Board Meetings 5
Steering Committee Meetings 5
Project Management Committee Meetings 20
Public Events (Meetings & Informational Open House
Events)
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Executive Summary November 2024
ES-4. Basin Setting
The Subbasin is located to the west of the SacramentoSan Joaquin River Delta (Delta) and is bounded by the Sierra Nevada foothills to the east, the San Joaquin
River to the west, Dry Creek to the north, and
Stanislaus River to the south. In the eastern portion of the Subbasin, groundwater flows from east to west and
generally mirrors the westward sloping topography of
the geologic formations. In the western portion of the
Subbasin, groundwater flows eastward toward areas
with relatively lower groundwater elevation. Surface
water generally flows from east to west, with the major river systems traversing the Subbasin being the
Calaveras, Mokelumne, and Stanislaus rivers. Multiple
smaller streams flow into the San Joaquin River, which
flows from south to north. The location of the Subbasin is shown in Figure ES-3.

ES-5. Existing Groundwater Conditions
Groundwater levels in some portions of the Subbasin
have been declining for many years, while groundwater levels in other areas of the Subbasin have remained stable or increased in recent years. The change in groundwater levels varies across the Subbasin, with the greatest declines occurring in the central portion of the Subbasin. The western and southern portions of the Subbasin have experienced less change in groundwater levels, in part due to the minimal groundwater pumping in the Delta area to the west and the import of surface water for agricultural and urban uses. In the most recent years, groundwater levels show a general trend of increasing as a result of two signficantly wet water years following two critically dry water years. It has also been established through isotope analysis that the implementation of the Tecklenberg project has added to groundwater levels in the project area.

Groundwater quality in the Subbasin varies by location. Areas along the western margin have historically had higher levels of salinity. Salinity may be naturally occurring or the result of human activity. Sources of salinity in the Subbasin include Delta sediments, deep saline groundwater, and irrigation return water. Total dissolved solids (TDS), which is a measure of all inorganic and organic substances present in a liquid in molecular, ionized, or colloidal suspended form, and chloride are commonly used to measure salinity. The Groundwater Ambient Monitoring and Assessment (GAMA) Program includes numerous water quality monitoring sites in the Subbasin compiled from different sources, shown in Figure ES-4. Maximum TDS concentrations across the Subbasin have been reported as high as 2,500 milligrams per liter (mg/L) along portions of the Subbasin’s western boundary. Maximum chloride concentrations have been reported at concentrations greater than 2,000 mg/L, with higher concentrations measured in the central and western regions of the Subbasin. For drinking water, California has three secondary maximum contaminant level (SMCL) standards for TDS, all based on aesthetic considerations such as taste and odor, not public health concerns. These are 500 mg/L (recommended limit), 1,000 mg/L (upper limit), and 1,500 mg/L (short-term limit). TDS concentrations decrease significantly to the east, to typically less than 500 mg/L (the recommended limit for aesthetic considerations). The SMCL for chloride is 250 mg/L. Chloride concentrations are typically low across the Subbasin with the majority of measurements falling within the 0-250 mg/L range. Elevated concentrations of other constituents, such as nitrate, arsenic, and point-source contaminants, are generally localized and not widespread and are Figure ES- 2: Basin Setting
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Executive Summary November 2024
generally related to natural sources or land use activities. The GSP establishes ongoing monitoring of salinity (as TDS and chloride) and uses publicly available groundwater quality data to assess groundwater quality relative to arsenic, nitrate, and a number of other common water quality constituents to fill data gaps and identify potential trends of concern.

While the total volume of groundwater in storage in the Subbasin has declined over time, groundwater storage
reduction has not historically been an area of concern in the Subbasin, as there are large volumes of fresh water stored in the aquifer. The total fresh groundwater in storage was estimated at over 50 million-acre-feet (MAF) in 2015. The amount of groundwater in storage has decreased by
approximately 0.01 percent per year (or -0.34 MAF per year) between 1995 and 2023. As such, it is highly unlikely the Subbasin will experience conditions under which the volume of stored groundwater poses a concern, although the depth to access that groundwater does pose a concern.

Land subsidence has not historically been an area of concern in the Subbasin, and there are no records of land subsidence caused by groundwater pumping in the Subbasin.

Seawater intrusion is not considered an applicable sustainability indicator for the Eastern San Joaquin Subbasin as the adjoining Sacramento-San Joaquin River Delta (Delta) is managed as a freshwater body, there is minimal pumping near the Delta, and there are relatively low chloride concentrations in the Subbasin.

Surface waters can be hydraulically interconnected with the groundwater system, where the stream baseflow is either derived from the aquifer (gaining stream) or recharged to the aquifer (losing stream). If the water table beneath the stream substantially lowers as a result of groundwater pumping, the stream may disconnect entirely from the underlying aquifer. Major river systems in the Subbasin are highly managed to meet instream flow requirements for fisheries, water quality standards, and water rights of users downstream. The Eastern San Joaquin Water Resources Model (ESJWRM) Version 3.0 was used to identify interconnected reaches of rivers and streams contained within or bounding the Subbasin by comparing monthly groundwater elevations from the historical calibration of the ESJWRM to streambed elevations along the streams represented. The Mokelumne, Stanislaus, and lower San Joaquin Rivers were found to be connected at least 80 percent of the time over the model simulation period, and the Calaveras River less than 20 percent of the time. ESJWRM Version 3.0 was also used to evaluate current conditions to those simulated for Water Year 2015 (representing dry conditions with low groundwater levels after a multi-year drought). The resultant trends were very similar to historical gains and losses, with the exception of the Stanislaus River, which has a high number of stream nodes in the center portion of the river that are losing under current conditions. ESJWRM Version 3.0, while the best available tool at the time of analysis, contains uncertainty preventing the GSAs from having sufficient data to determine if or when streams or reaches are connected to the groundwater table with this level of granularity. The GSAs will be collecting more data with the new ISW monitoring wells to help inform this analysis going forward.

Figure ES- 3: GAMA Water Quality
Sampling Locations
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Executive Summary November 2024
ES-6. Sustainable Management Criteria
SGMA introduces several terms to measure sustainability, including:

Sustainability Indicators – Sustainability indicators refer to any of the effects caused by groundwater conditions occurring throughout the Subbasin that, when significant and unreasonable, cause undesirable results. The six sustainability indicators identified by DWR are the following:
• Chronic lowering of groundwater levels indicating a significant and unreasonable depletion of supply if continued over the planning and implementation horizon
• Significant and unreasonable reduction of groundwater storage • Significant and unreasonable seawater intrusion
• Significant and unreasonable degraded water quality
• Significant and unreasonable land subsidence that substantially interferes with surface land uses • Depletions of interconnected surface water that have significant and unreasonable adverse impacts on beneficial uses of the surface water
Sustainability Goal – This goal is the culmination of conditions resulting in a sustainable condition (absence of undesirable results) within 20 years.

Undesirable Results – Undesirable results are the significant and unreasonable occurrence of conditions that adversely affect groundwater use in the Subbasin, including reduction in the long-term viability of domestic, agricultural, municipal, or environmental uses of the Subbasin’s groundwater. Categories of undesirable results are defined through the sustainability indicators.

Minimum Thresholds – Minimum thresholds are numeric values for each sustainability indicator and are used to define when undesirable results occur. Undesirable results occur if minimum thresholds are exceeded in an established percentage of sites in the Subbasin’s representative monitoring network.

Measurable Objectives – Measurable objectives are a specific set of quantifiable goals for the maintenance or improvement of groundwater conditions.

The method prescribed by SGMA to measure undesirable results involves setting minimum thresholds and measurable objectives for a series of representative monitoring wells or sites for each sustainability indicator. Representative monitoring wells are identified to provide a basis for measuring groundwater conditions (levels and quality) throughout a basin or subbasin without having to measure each well, which would be cost prohibitive. In the Eastern San Joaquin Subbasin, representative wells were selected based on history of recorded groundwater level and/or quality data and potential to effectively represent the groundwater conditions. For the sustainability indicator relating to inelastic land subsidence, representative montioring locations measure ground surface elevations. Similar to the monitoring networks for groundwater levels and quality, monitoring sites were selected based on the history of recorded data and the potential to effectively represent conditions across the Subbasin. As determined following further evaluation, the sustainability indicator relating to significant and unreasonable seawater intrusion was deemed not applicable to the Eastern San Joaquin Subbasin as the Subbasin is not on the coast, and saltwater intrusion through the Delta is managed by upstream reservoir releases to maintain salinity concentrations around 2 parts per thousand.

A total of 23 representative wells were identified for measurement of groundwater levels in the Subbasin, 21 representative wells were identified for groundwater quality monitoring, and 12 representive wells were identified for monitoring related to interconnected surface water. For measurements related to inelastic land subsidence, four CGPS stations and six survey benchmarks were selected to form the monitoring network for this sustainability indicator. The GSP uses groundwater level data as the basis for evaluating conditions for groundwater storage.

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Executive Summary November 2024
Minimum thresholds and measurable objectives were developed for each of the representative monitoring sites. Figure ES-5 shows a typical relationship of the minimum thresholds, measurable objectives, and historical groundwater level data for a sample groundwater level representative monitoring well. Similar analyses can be made for groundwater quality and land subsidence.

Minimum thresholds for groundwater levels were
developed with reference to historical drought low
conditions and domestic well depths. Specifically,
minimum thresholds were established based on
the historical (2015) drought low plus a buffer of
the historical fluctuation or the 10th percentile
domestic well depth, whichever is shallower –
establishing levels that are protective of 90
percent of domestic wells and wells that
community water systems may rely on. In
municipalities with ordinances requiring the use of
City water (water provided by the City’s municipal
wells), the 10th percentile municipal well depth is
used in place of the 10th percentile domestic well
depth criteria.

Measurable objectives for groundwater levels
were established based on the historical (2015)
drought low and provide a buffer above the
minimum threshold. A table summarizing
minimum thresholds and measurable objectives is included in Chapter 3 of this Amended GSP. Graphs showing the minimum threshold and measurable objective for each of the representative wells are contained in an appendix to the GSP.

The minimum thresholds and measurable objectives for groundwater levels are used for the groundwater storage sustainability indicator, as this sustainability indicator is strongly linked to groundwater levels. The groundwater levels minimum thresholds are found to be protective of groundwater storage
Minimum thresholds for groundwater quality were defined by considering two primary beneficial uses at risk of undesirable results related to salinity: drinking water and agriculture uses. Minimum thresholds are 1,000 mg/L total dissolved solids (TDS), 250 mg/L chloride, or the groundwater concentration of those constituents as measured in 2015 at the representative monitoring location, whichever is greater. These values reflect the Secondary Maximum Contaminant Limit (SMCL) for the two constituents of concern (TDS and chloride), plus ackowledges groundwater quality degradation that was already occurring in 2015. Furthermore, these values reflect the agricultural nature of the Subbasin.

Measurable objectives for groundwater quality were set at 600 mg/L for TDS, and the maximum maximum recent historical measurement (as measured between 2015 and 2023) for chloride. The TDS measurable objective of 600 mg/L was developed based on the TDS recommended SMCL for drinking water of 500 mg/L with an added 100 mg/L buffer. A measurable objective of 600 mg/L TDS is close to the recommended SMCL of 500 mg/L and significantly below the upper limit SMCL of 1,000 mg/L, and is considered adequate for drinking water and agricultural uses. The chloride measurable objective was set equal to the maximum measured chloride concentration as measured during recent historical conditions (between 2015 and 2023), accounting for fluctuations in constituent concentrations with hydrologic conditions.

The minimum threshold for inelastic land subsidence in the Subbasin was set at no more than 0.2 foot/year [2.4 inches/year] in any five-year period between 2020 and 2040, resulting in no more than a total additional 2 feet (24 inches) of land subsidence by 2040. This is set within the same magnitude of estimated error of the InSAR data (+/- 0.1 foot [0.03 m]), which is currently the most comprehensive tool available for measuring subbasin-wide land subsidence consistently each year, based on historical subsidence rates. Additionally, the minimum threshold of 24 inches of additional subsidence by 2040 reflects the Figure ES- 4: Sample Relationship Between Minimum
Threshold and Measurable Objective
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2024 Groundwater Sustainability Plan Amendment ES-7
Executive Summary November 2024
historical subsidence level with an added buffer, and is in line (both by method and magnitude) with the minimum thresholds established by other nearby basins overlying the Corcoran Clay.

The measurable objective for inelastic subsidence is based on the long-term avoidance of land subsidence: 0 ft/year, on a long-term average. This measurable objective is set recognizing the interconnectedness of the Subbasin with surrounding subbasins, and the ability to meet this objective is dependent on the successful management of all nearby subbasins Finally, the minimum thresholds and measurable objectives established for interconnected surface water representative monitoring wells both use groundwater levels as a metric. Groundwater level data are used to calculate water table gradients and, therefore, the volume of water gained and lost. The interconnected surface water minimum thresholds and measurable objectives for wells with historical groundwater level observations are the same as for the chronic lowering of groundwater levels minimum thresholds. Analyses were conducted to demonstrate that the groundwater level minimum thresholds are protective of stream depletions and stream-aquifer interactions (stream connectivity, stream gains and losses, and stream gains and losses as a percentage of streamflow), and therefore the use of these minimum thresholds is justified. For new representative montiroing wells without historic data sets, minimum thresholds and measurable objectives will be established after at least four years of data have been collected, including data for at least one wet year and one dry or critical year during that time period, utilizing the methodologies outlined in Chapter 3 of this GSP.

ES-7. Water Budgets
The Eastern San Joaquin Subbasin has been in an overdraft condition for many years. Overdraft occurs when the amount of groundwater extracted exceeds the long-term average
groundwater recharged.

The groundwater evaluations conducted as a part of the
developmnet of this GSP Amendment provide revised
estimates of the historical, current, and projected
groundwater budget conditions. The current analysis was prepared using the best available information and through updates to the Subbasin’s groundwater modeling tool, the Eastern San Joaquin Water Resources Model (ESJWRM),
Version 3.0. It is anticipated that as additional information becomes available, the model will continue to be updated to continuously refine estimates of annual pumping and
overdraft .

As part of the 5-year Periodic Evaluation and preparation of this Amended GSP, the ESJWRM was updated to Version

3.0 to incorporate new data relating to layering, streams, land use, urban water demand, surface water supply and
water deliveries and to extend the simulation period through Water Year 2023. The model was then recalibrated for the extended period, and water budgets were updated for historical conditions, current conditions, projected conditions baseline, and projected conditions with the impacts of climate change. Projected conditions scenarios were also updated to incorporate an updated list of projects and management actions as well as updates to the sustainable yield estimate.

Based on these analyses, at projected groundwater pumping levels, the long-term groundwater pumping offset and/or recharge required for the Subbasin to achieve a 0 AF/year change in storage is approximately 95,000 AF/year. Groundwater levels are expected to continue to decline based on projections of current land and water uses. Projects and management actions that offset groundwater pumping and/or increase recharge will help the Subbasin reach sustainability, as illustrated in Figure ES-6
Figure ES- 5: Subbasin-Wide Total Groundwater
Pumping and Offsets Required to Achieve
Sustainability
EXHIBIT 1
736
2024 Groundwater Sustainability Plan Amendment ES-8
Executive Summary November 2024
The projected Subbasin water budget was also evaluated under climate change conditions, which simulate higher demand requiring increased groundwater pumping despite more precipitation and streamflows. The updated version of the Projected Conditions Baseline with Climate Change (PCBL-CC) largely used the same perturbation factors (2070 Central Tendency climate change conditions) as the original simulation, but the updated PCBL-CC extended the simulation time period by three additional years. The overdraft modeled under climate
change conditions is simulated to increase above projected conditions without climate change, requiring long-term
groundwater pumping offset and/or recharge required for the Subbasin to achieve a 0 AF/year change in storage is approximately 166,000 AF/year.

ES-8. Monitoring Networks
This GSP Amendment outlines the representative
monitoring networks for five of the six sustainability
indicators. (Seawater intrusion is no longer considered an applicable sustainability indicator for the Eastern San Joaquin Subbasin.) The objective of these monitoring
networks is to monitor conditions across the Subbasin and to detect trends toward undesirable results. Specifically, the monitoring networks were developed to do the
following:
• Monitor impacts to the beneficial uses or users of
groundwater
• Monitor changes in groundwater conditions and
land surface elevations relative to measurable objectives and minimum thresholds • Demonstrate progress toward achieving measurable objectives described in the GSP There are four representative monitoring networks in the Eastern San Joaquin Subbasin: two representative networks for water levels (one for the chronic lowering of groundwater levels sustainability indicator and one for the interconnected surface waters sustinability indicator), a representative network for groundwater quality, and a representative network for inelastic land subsidence. Representative networks are used to determine compliance with the minimum thresholds.

The monitoring networks were designed by evaluating data from the DWR’s California Statewide Groundwater Elevation Monitoring (CASGEM) Program, the United States Geological Survey (USGS), the United States Army Corps of Engineers (USACE), the California Department of Transportation (CalTrans), the San Joaquin County Department of Public Works, and participating GSAs. The groundwater level and interconnected surface water monitoring networks consist largely of wells that are already being used for monitoring in the Subbasin. New wells were added to the monitoring networks, including one well located in the Delta, two deep, multi-completion monitoring wells constructed under DWR’s Technical Support Services (TSS) program, and five new shallow monitoring wells for interconnected surface water assessment. Figure ES-7 shows the location of existing monitoring sites for all representative monitoring networks.

Wells in the monitoring networks for water levels (for both the groundwater level and interconnected surface water sustainability indicators) and groundwater quality will be measured on a semi-annual schedule. Monitoring for subsidence will also occur semi-annually. Historical measurements have been entered into the Subbasin Data Management System (DMS), and future data will also be stored in the DMS.

Figure ES- 6: Monitoring Sites
EXHIBIT 1
737
2024 Groundwater Sustainability Plan Amendment ES-9
Executive Summary November 2024
A summary of the monitoring sites in the representative monitoring networks is shown in the table below.

Summary of Representative Monitoring Network Wells/Stations Data Collected Well/Station
Count
Groundwater Level 23
Interconnected Surface Water 12
Groundwater Quality 21
Subsidence (CGPS stations and survey benchmarks) 10
ES-9. Data Management System
The Eastern San Joaquin DMS was built on a flexible, open software platform that uses familiar Google maps and charting tools for analysis and visualization. The DMS serves as a data-sharing portal that enables use of the same data and tools for visualization and analysis. These tools support sustainable groundwater management and create transparent reporting about collected data and analysis results.

The DMS is web-based; the public can easily access
this portal using common web browsers such as
Google Chrome, Firefox, and Microsoft Edge. The
DMS is currently populated with available historical
data. Future data will also be entered into the system
as it is collected.

The DMS portal provides easy access and the ability
to query information stored in the system.

Groundwater data can be plotted for any of the
available data points, providing a pictorial view of
historical and current data.

Recently, a mobile and tablet interface was
developed for the DMS to facilitate the real-time
upload of data collected in the field. The mobile
interface is implemented using the Esri ArcGIS Field
Maps mobile app (or the Collector app if already
installed) and is integrated with the DMS via web
services to ArcGIS Online*. The mobile interface is
intended to provide all ESJGWA staff and their
consultants with an easy-to-use interfaces to collect
well and groundwater related data in the field. Data
collected using the mobile interfaces are pulled into
the DMS on a nightly basis where it is quality
controlled prior to insertion into the database.

The DMS can be accessed at this link using
the Guest Login:
https://opti.woodardcurran.com/esj/
Figure ES- 8: Opti DMS Screenshot
Figure ES- 8: Typical DMS Data Display
EXHIBIT 1
738
2024 Groundwater Sustainability Plan Amendment ES-10
Executive Summary November 2024
ES-10 Projects and Management Actions
Achieving sustainability in the Subbasin requires implementation of projects and management actions. The Subbasin will achieve sustainability by implementing water supply projects that either replace groundwater use or supplement groundwater supplies to attain the current estimated pumping offset and/or recharge need of 95,000 AF/year. It should be noted that this number will be reevaluated in the future after additional data are collected and analyzed. In addition, three projects have been identified that support demand conservation and reduction activities, including water use efficiency upgrades. While the implementation of projects to address sustainabilty has been and will continue to be the cornerstone of the ESJ GSP, the Subbasin is committed to developing a Demand Management Program that would include pumping restrictons if projects are not implemented as expected.

Although the ESJGWA does not have direct authority to require GSAs to implement projects, the ESJGWA will coordinate analysis of GSA-level demands and will compile annual or biannual reports to evaluate progress. If projects do not progress, or if monitoring efforts demonstrate that the projects are not effective in achieving stated recharge and/or offset targets, the Subbasin’s Demand Management Program, a new management action in this GSP, will be implemented.

Projects to increase water supply availability in the Subbasin were identified by individual GSAs. The initial set of projects was reviewed with the ESJGWA Board, Steering Committee, and Workgroup. A final list of 41 potential projects are included in the GSP, representing a variety of project types including direct and in-lieu1recharge, intra-basin water transfers, demand conservation, water recycling, and stormwater reuse. Four new additional projects were approved by the ESJGWA Board at their September 11, 2024 meeting, and are not included in below. More information on these projects is included in Appendix 6-A. With the addition of these four projects, the GSP now includes 45 total projects. Projects are classified into two categories based on project status: Category A and Category B. Category A projects are those that are completed or are anticipated to advance in the next five years and have existing water rights or agreements. Category B projects are those that are not anticipated to advance in the next five years, but may be implemented in the future. Category A projects were simulated in the projected water budget to evaluate their effectiveness on achieving Subbasin sustainability. Category B projects may be elevated to a Category A project should feasibility studies demonstrate a viable project, if water rights or contracts are firmly identified, if partnerships are formed, and if economic evaluation demonstrate that the projects are cost effective, and remain part of the overall adaptive management strategy that the Subbasin is utilizing in GSP implementation to achieve and maintain Subbasin sustainability. These projects are summarized below. 1 In-lieu recharge refers to the use of surface water or recycled water supplies for applications where groundwater is currently used. This “in-lieu” use reduces groundwater pumping and allows groundwater to remain in the aquifer.

EXHIBIT 1
739
2024 Groundwater Sustainability Plan Amendment ES-11
Executive Summary November 2024
Project Name Project Type Project
Proponent
Measurable
Objective
Expected to
Benefit
Current Status
Time-table
(initiation and
completion)
Estimated
Capital Costl
Estimated
Annual O&M
Costs
Required
Permitting and
Regulatory
Process1
Maximum
Recharge Benefit
(AF/year)
Category A Projects - projects that were completed or are anticipated to advance in the next five years and have existing water rights or agreements Lake Grupe Inlieu RechargeIn-lieu Recharge SEWD Groundwater levels
Completed 2020-2023 $2.3 M $330,000 Installation for
new intake and
pipeline requires
permits from

DFW, CVFPB,
RWQCB, and
USACE
4,900
SEWD Surface
Water
Implementation
Expansion
In-lieu Recharge SEWD Groundwater
levels
Implementation 2019-2029 $750,000 $100,000 Permit approvals from DFW,
RWQCB,
CVFPB, and
USACE by
private
landowners
19,000
White Slough
Water Pollution
Control Facility
Expansion
Recycling/
In-lieu
Recharge/Direct
Recharge
City of Lodi Groundwater
levels
Construction complete 2019-2020 $6 M $4,664 None (permitting complete)
1,000
CSJWCD Capital
Improvement
Program
In-lieu Recharge CSJWCD Groundwater
levels
Can be implemented
immediately
2020-2027, ongoing with 7-
year completion
cycles
N/A $50,000 Individual
applications
need CSJWCD
Board approval
and possible
streambed
alteration
permits
24,000
EXHIBIT 1
740
2024 Groundwater Sustainability Plan Amendment ES-12
Executive Summary November 2024
Project Name Project Type Project
Proponent
Measurable
Objective
Expected to
Benefit
Current Status
Time-table
(initiation and
completion)
Estimated
Capital Costl
Estimated
Annual O&M
Costs
Required
Permitting and
Regulatory
Process1
Maximum
Recharge Benefit
(AF/year)
NSJWCD South
System
Modernization
In-lieu Recharge NSJWCD Groundwater
levels
Environmental review
complete, funding
secured for Phases 1, 2
and 3. Landowner
improvement district
formed. Phases 1-2
complete.
2018-2025 for
Phases 1, 2, 3;
2025-2028 for
Phase 4; 2028-
2035 for future
phases
Phase 1&2:
$7 M
Phase 3:
$4 M
Phase 4:
$8 M
Future
Phases:
$10-20 M
Phase 1&2:
$200,000
Phase 3:
$200,000
Phase 4:
$200,000
Future Phases:
$200,000
Permits for
pump station
work have been
completed;
minor grading
and road
encroachment
permits may be
needed
10,000
Long-term Water
Transfer to
SEWD and
CSJWCD
Transfers SSJ GSA Groundwater
levels
Infrastructure is in
place. CEQA completed
and agreements in
place
2019-2021 N/A $9 M Project must
comply with
CEQA
20,000
South System
Groundwater
Banking with
East Bay
Municipal Utilities
District (EBMUD)
In-lieu Recharge NSJWCD Groundwater
levels
Pilot Dream Project will
be complete by
February 2024.

Working on expanded
banking project
2020-2024 $5 M $400,000
SWCRB change
petition for
Permit 10478
and San Joaquin
County
groundwater
export permit,
and regulatory
permits as
needed
4,000
NSJWCD North
System
Modernization/
Lakso Recharge
In-Lieu Recharge NSJWCD Groundwater
levels
Constructed Phase 1A,
in progress on Phase
1B. Planning Phase 2
2021-2026 $7 M $150,000
Regulatory
permits as
needed
4,000
Tecklenburg
Recharge Project Direct Recharge NSJWCD Groundwater levels Substantially complete 2022-2024 $1 M $400,000 CEQA review
and possible
grading permit
2,000
City of Stockton
Phase 1:

Groundwater
Recharge Project
Direct Recharge City of
Stockton
Groundwater
levels
Basin design in
progress. Construction
to begin spring 2025.
2022-2026 $11.5 M To be
Determined
Project must
comply with
CEQA
20,000
West
Groundwater
Recharge Basin
Direct Recharge SEWD Groundwater
levels
Ongoing 2032 To be
Determined
To be
Determined
To be
Determined
16,000
EXHIBIT 1
741
2024 Groundwater Sustainability Plan Amendment ES-13
Executive Summary November 2024
Project Name Project Type Project
Proponent
Measurable
Objective
Expected to
Benefit
Current Status
Time-table
(initiation and
completion)
Estimated
Capital Costl
Estimated
Annual O&M
Costs
Required
Permitting and
Regulatory
Process1
Maximum
Recharge Benefit
(AF/year)
NSJWCD Private
Pump
Partnerships
In-Lieu
Recharge/Direct
Recharge
NSJWCD Groundwater
levels Ongoing 2024 To be Determined
To be
Determined
To be
Determined 3,000
Oakdale
Irrigation District
In-lieu and Direct
Recharge Project
Direct Recharge/InLieu Recharge OID Groundwater
levels Ongoing 2023-2032 To be Determined
To be
Determined
To be
Determined 25,000
City of Stockton
Advanced
Metering
Infrastructure
Conservation City of
Stockton
Groundwater
levels
In progress. Contract
awarded in March 2024.
2023-2028 $17 M To be
determined
Not determined 2,000
Total Category A 154,900
Category B Projects - projects that are not anticipated to advance in the next five years, but may be implemented in the future, particularly if Category A projects do not fully achieve stated recharge and/or offset targets or do not produce a response as simulated in the model City of
Manteca
Advanced
Metering
Infrastructure
Conservation City of
Manteca
Groundwater
levels
Experiencing Delays Not determined $650,000 $300,000 None 272 City of Lodi
Surface Water
Facility
Expansion &
Delivery
Pipeline
In-lieu Recharge City of
Lodi
Groundwater
levels
Planning phase 2030-2033 $4 M $2,340,000 SWRCB
permitting and
CEQA required
4,750
BNSF Railway
Company
Intermodal
Facility
Recharge
Pond
Direct Recharge CSJWCD Groundwater
levels
Planning phase 2020-2025 N/A $50,000 Streambed
alteration permit
1,000
EXHIBIT 1
742
2024 Groundwater Sustainability Plan Amendment ES-14
Executive Summary November 2024
Project Name Project Type Project
Proponent
Measurable
Objective
Expected to
Benefit
Current Status
Time-table
(initiation and
completion)
Estimated
Capital Costl
Estimated
Annual O&M
Costs
Required
Permitting and
Regulatory
Process1
Maximum
Recharge Benefit
(AF/year)
Manaserro
Recharge
Project
Direct Recharge NSJWCD Groundwater
levels
Planning phase 2023-2025 $500,000 $50,000 CEQA review,
possible grading
permit, possible
water right
change petition
8,000
City of Escalon
Wastewater
Reuse
Recycling/
In-lieu Recharge/
Transfers
SSJ GSA Groundwater
levels
Planning phase 2020-2028 To be
determined$18
M
To be
determined$40
0,000
CEQA review,
RWQCB
permits, and
road
encroachment
permits
672
City of Ripon
Surface Water
Supply
In-lieu Recharge SSJ GSA Groundwater
levels
Design complete;
environmental
permitting underway;
negotiations for the right
to connect are
underway.
2028-2030 To be
determined
To be
determined
NEPA
Categorical
Exclusion,
CEQA Mitigated
Negative
Declaration, and
road
encroachment
permits
6,000
City of Escalon
Connection to
Nick DeGroot
Water
Treatment
Plant
In-lieu Recharge SSJ GSA Groundwater
levels
Conceptual design;
environmental review
complete; Council
approval are pending
further design work and
rate study
2028-2030 To be
determined
To be
determined
Road
encroachment
permits
2,015
EXHIBIT 1
743
2024 Groundwater Sustainability Plan Amendment ES-15
Executive Summary November 2024
Project Name Project Type Project
Proponent
Measurable
Objective
Expected to
Benefit
Current Status
Time-table
(initiation and
completion)
Estimated
Capital Costl
Estimated
Annual O&M
Costs
Required
Permitting and
Regulatory
Process1
Maximum
Recharge Benefit
(AF/year)
Farmington
Dam
Repurpose
Project
Direct Recharge SEWD Groundwater
levels
Planning/Initial Study 2030-2050 To be
determined
To be
determined
Permits and
approvals form

SWRCB, USBR,

DFW, RWQCB,
CVFPB, and
USACE
60,000
Mobilizing
Recharge
Opportunities
Direct Recharge San
Joaquin
County
Groundwater
levels
Project Development 2024-2040 Not
determined
Not determined Not determined 158,000
NSJWCD
Winery
Recycled
Water
Recycling/
In-Lieu Recharge/
Direct Recharge
NSJWCD Groundwater
levels
Conceptual planning
and discussion
2025-2027 To be
determined
To be
determined
WDR permitting
through the
RWCQB and
minor permits for
pipeline
construction
750
SSJID Storm
Water Reuse
Storm Water/
In-lieu Recharge/
Direct Recharge
SSJ GSA Groundwater
levels
Planning phase 2027-2030 To be
determined$30
M
To be
determined$30,
000
CEQA review
and road
encroachment
permits
1,100
WallaceBurson
Conjunctive
Use Program
Conjunctive
Use/Direct Recharge
Eastside
GSA
Groundwater
levels
Conceptual planning
and discussion 2030-2040 To be determined
To be
determined Not determined 3,000
Calaveras
River
Wholesale
Water Service
Expansion
In-Lieu Recharge Eastside
GSA
Groundwater
levels Conceptual planning 2020-2040 To be determined
To be
determined Not determined 600
EXHIBIT 1
744
2024 Groundwater Sustainability Plan Amendment ES-16
Executive Summary November 2024
Project Name Project Type Project
Proponent
Measurable
Objective
Expected to
Benefit
Current Status
Time-table
(initiation and
completion)
Estimated
Capital Costl
Estimated
Annual O&M
Costs
Required
Permitting and
Regulatory
Process1
Maximum
Recharge Benefit
(AF/year)
Recycled
Water to
Manteca Golf
Course
Recycling City of
Manteca
Groundwater
levels
12-in pipeline installed.

Waiting for DWR to
determine grant
recipients
To Be
Determined
To be
determined
To be
determined Not determined 406
Threfall Ranch
Reservoir, InLieu and Direct
Recharge
Project
In-Lieu
Recharge/Direct
Recharge
Eastside
GSA
Groundwater
levels Design 2025 To be determined
To be
determined Not determined 2,000
Perfecting
Mokelumne
River Water
Right
In-Lieu Recharge
San
Joaquin
County
Groundwater
levels Planning 2024-2025
$125,000
(spent to date)
Total TBD
To be
determined Not determined 158,000
North System
Groundwater
Recharge
Project - Phase
2 Direct Recharge NSJWCD Groundwater
levels
Design phase with
planned construction in
2025-2026
2026-2029 $10 M $100,000 Not determined 3,000
Stormwater
Collection,
Treatment, and
Infiltration
Direct Recharge/
Stormwater
City of
Manteca
Groundwater
levels Planning/Initial Study To Be Determined
To be
determined
To be
determined Not determined To Be Determined
Off-Stream
Regulating
Reservoir
Direct Recharge SEWD Groundwater
levels Conceptual Phase 2026-2050 To be determined
To be
determined Not determined To Be Determined
On-Farm
Recharge
Project
Direct Recharge SEWD Groundwater
levels Planning/Initial Study 2024-2030 N/A $100,000 Not determined To Be Determined Bellota Weir
Modifications
Project
Direct Recharge/
Stormwater SEWD Groundwater
levels
SRF loan application
submitted. $12.3M
grant received. Minor
construction started
2023-2030 $ 85 M $1.5M
USACE,

FWS,CVFPB,CE

QA,NEPA
5,200
EXHIBIT 1
745
2024 Groundwater Sustainability Plan Amendment ES-17
Executive Summary November 2024
Project Name Project Type Project
Proponent
Measurable
Objective
Expected to
Benefit
Current Status
Time-table
(initiation and
completion)
Estimated
Capital Costl
Estimated
Annual O&M
Costs
Required
Permitting and
Regulatory
Process1
Maximum
Recharge Benefit
(AF/year)
Water Supply
Enhancement
Project -
Distribution
Pipelines
In-Lieu
Recharge/Direct
Recharge
SEWD Groundwater
levels Design 2024-2040 $7M To be determined

RWQCB,CEQA,

USACE,CVFPB,
DFW
17,000
Water
Treatment
Plant Aquifer
Storage
Recovery Well
- 7401
Direct Recharge SEWD Groundwater
levels Implementation 2024-2026 $1.5 M To be determined

RWQCB,CEQA,
NEPA 2,420
Beckman Well Direct Recharge SEWD Groundwater
levels Refurbish 2024-2028 $200,000 N/A RWQCB,CEQA 800
West Linden
Project
In-Lieu
Recharge/Direct
Recharge
SEWD Groundwater
levels Planning/Design 2024-2035 $60M To be determined

CEQA,RWQCB,
road
encroachment
permits
60,000
Water Supply
Enhancement
Project - Direct
Recharge
Direct Recharge SEWD Groundwater
levels Design 2024-2030 To be determined
To be
determined Not determined To Be Determined
SSJID Water
Master Plan -
System
Improvements
In-Lieu Recharge SSJ GSA Groundwater
levels
Feasibility study
complete 2023-2040 $ 30 – 40 M To be determined Not determined 15,000 Total Category B 509,985
1 Acronyms defined: Stockton East Water District (SEWD), Central San Joaquin Water Conservation District (CSJWCD), North San Joaquin Water Conservation District (NSJWCD), California Department of Fish and Wildlife (DFW), Central Valley Flood Protection Board (CVFPB), Regional Water Quality Control Board (RWQCB), and U.S. Army Corps of Engineers (USACE), State Water Resources Control Board (SWRCB), California Environmental Quality Act (CEQA), U.S. Bureau of Reclamation (USBR), National Pollutant Discharge Elimination System (NPDES), Waste Discharge Requirements (WDR).

EXHIBIT 1
746
2024 Groundwater Sustainability Plan Amendment ES-18
Executive Summary November 2024
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EXHIBIT 1
747
2024 Groundwater Sustainability Plan Amendment ES-19
Executive Summary November 2024
ES-11 GSP Implementation
The overdraft condition in the Subbasin requires either projects to offset groundwater pumping and/or increase recharge, or pumping reduction. The exact amount of required offset/recharge will be reevaluated after additional data are collected and analyzed. As previously noted, the overarching philosophy of the ESJ GSP is to implement projects to address the overdraft condition. Should the projects be delayed or not provide the benefits identified, the Subbasin will implement the Demand Management Program, a new management action in this GSP.

Projects will be administered by the GSA project proponents. GSAs may elect to implement projects individually or jointly with one or more GSAs or with the ESJGWA.

Implementing the GSP will require numerous management activities that will be undertaken by the ESJGWA, including the following:
• Monitoring and recording of groundwater levels and groundwater quality data • Maintaining and updating the Subbasin DMS with newly collected data • Maintaining and updating the Subbasin Data Management System (DMS) with newly collected data • Addressing identified data gaps
• Annual monitoring of progress toward sustainability
• Annual reporting of Subbasin conditions to DWR as required by SGMA • Refining Subbasin model and water budget planning estimates • Evaluating the GSP once every 5 years and amending the plan if warranted The ESJGWA Board adopted a preliminary schedule for project implementation. Project implementation is scheduled to begin in 2020, with full implementation by 2040. This approach provides adequate time to put in place methods necessary to refine model estimates and verify project cost effectiveness.

ES-12. Funding
Implementation of the GSP requires funding sources. To the degree they become available, outside grants will be sought to assist in reducing cost of implementation to participating agencies, residents, and landowners of the Subbasin. However, there will be a need to collect funds to support implementation.

The areas associated with ESJGWA-wide management and GSP implementation will be borne by the ESJGWA through contributions from the member GSAs, under a cost-sharing arrangement. These costs include:
• ESJGWA administration
• Groundwater level monitoring and reporting
• Groundwater quality monitoring and reporting
• Inelastic land subsidence monitoring and reporting
EXHIBIT 1
748
2024 Groundwater Sustainability Plan Amendment ES-20
Executive Summary November 2024
• Water use estimation
• Data management
• Stakeholder engagement
• Oversight of management actions
• Annual Report preparation and submittal to DWR
• Developing and implementing a funding mechanism
• Grant applications
• GSP evaluation and updates, if warranted (every 5 years) For budgetary purposes, the estimated initial cost of these activities is on the order of $600,000 to $1 million per year excluding projects and management actions costs and costs associated with the installation of new monitoring wells and grant writing. Additional one-time costs, such as model refinement, are estimated to be on the order of $350,000.

GSAs will individually fund implementation of projects in their respective areas. Options for GSA funding include fees based on groundwater pumping, acreage, or combinations of these, and pursuit of any available grant funds. The GSAs will evaluate options for securing the needed funding on an individual basis.

The estimated initial costs of projects range from on the order of $50,000 to $85 million, depending on the project.

Annual project costs range from $3,000 to $9 million per year to provide funds for operations and maintenance.

EXHIBIT 1
749
2024 Groundwater Sustainability Plan Amendment 1-1
Agency Information, Plan Area, and Communication November 2024

1. AGENCY INFORMATION, PLAN AREA, AND COMMUNICATION

1.1 INTRODUCTION AND AGENCY INFORMATION

1.1.1 Purpose of the Groundwater Sustainability Plan
The purpose of this Groundwater Sustainability Plan (GSP) is to meet the regulatory requirements set forth in the three-bill legislative package consisting of Assembly Bill (AB) 1739 (Dickinson), Senate Bill (SB) 1168 (Pavley), and SB 1319 (Pavley), collectively known as the Sustainable Groundwater Management Act (SGMA). SGMA defines sustainable groundwater management as “management and use of groundwater in a manner that can be maintained during the planning and implementation horizon without causing undesirable results”, which are defined by SGMA as any of the following effects caused by groundwater conditions occurring throughout the basin (CA DWR, 2018):
• Chronic lowering of groundwater levels indicating a significant and unreasonable depletion of supply if continued over the planning and implementation horizon
• Significant and unreasonable reduction of groundwater storage • Significant and unreasonable seawater intrusion
• Significant and unreasonable degraded water quality, including the migration of contaminant plumes that impair water supplies
• Significant and unreasonable land subsidence that substantially interferes with surface land uses • Depletions of interconnected surface water that have significant and unreasonable adverse impacts on beneficial uses of the surface water
The Eastern San Joaquin Groundwater Subbasin (Eastern San Joaquin Subbasin or Subbasin) was identified by the Department of Water Resources (DWR) as critically overdrafted. The Eastern San Joaquin Groundwater Sustainability Plan (Eastern San Joaquin GSP, GSP, or the Plan) was originally developed to meet SGMA regulatory requirements by the January 31, 2020 deadline for critically-overdrafted basins while reflecting local needs and preserving local control over water resources. The 2020 GSP was subsequently revised in 2022 to address comments from DWR in their determination letter dated January 28, 2022. This 2024 GSP Amendment addresses comments in DWR’s July 6, 2023 determination letter approving the 2022 Revised GSP, and continues to provide a path to achieve and document sustainable groundwater management within 20 years following initial Plan adoption, promoting the long-term sustainability of locally-managed groundwater resources now and into the future.

While the Eastern San Joaquin GSP offers a new and significant approach to groundwater resource protection, it was developed within an existing framework of comprehensive planning efforts. Throughout the Eastern San Joaquin Region, several separate yet related planning efforts have occurred previously or are concurrently proceeding. The following figure (Figure 1-1) shows flagship reports from these efforts, which include integrated regional water management, urban water management, agricultural water management, watershed management, habitat conservation, and general planning. The Eastern San Joaquin GSP fits in with these prior planning efforts, building on existing local management and basin characterization. A description of prior planning efforts can be found in Section

1.2.2.7 of this document.

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Agency Information, Plan Area, and Communication November 2024 Figure 1-1: Interconnected Planning and Modeling Efforts for Water Resource Protection

1.1.2 Sustainability Goal
A sustainability goal is the culmination of conditions resulting in a sustainable condition (absence of undesirable results) within 20 years of the GSP’s initial adoption in 2020. The sustainability goal reflects this requirement and succinctly states the GSP’s objectives and desired conditions of the Subbasin.

The sustainability goal description for the Eastern San Joaquin Subbasin is to maintain an economically-viable groundwater resource for the beneficial use of the people of the Eastern San Joaquin Subbasin by operating the Subbasin within its sustainable yield or by modification of existing management to address future conditions. This goal will be achieved through the implementation of a mix of supply and demand type projects consistent with the GSP implementation plan (see Chapter 6: Projects and Management Actions).

Additional discussion of the sustainability goal can be found in Chapter 3: Sustainable Management Criteria.

1.1.3 Contact Information
The San Joaquin County Department of Public Works Director has been designated as Plan Manager and record keeper. As Plan Manager, the Public Works Director is tasked with submitting a single, jointly-composed GSP to DWR on behalf of the entire Subbasin.

Contact information for the submitting agency and Plan Manager is provided in Figure 1-2.

Figure 1-2: Plan Manager and
Agency Contact Information
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Agency Information, Plan Area, and Communication November 2024

1.1.4 Agency Information
The Eastern San Joaquin GSP was developed jointly by the members of the Eastern San Joaquin Groundwater Authority (ESJGWA), which is a joint powers authority formed by the 16 groundwater sustainability agencies (GSAs) within the Eastern San Joaquin Subbasin. The ESJGWA includes the Central Delta Water Agency (CDWA), Central San Joaquin Water Conservation District (CSJWCD), City of Lodi, City of Manteca, City of Stockton, Eastside San Joaquin GSA (Eastside GSA) (composed of Calaveras County Water District [CCWD], Calaveras County, Stanislaus County, and Rock Creek Water District), Linden County Water District (LCWD), Lockeford Community Services District (LCSD), North San Joaquin Water Conservation District (NSJWCD), Oakdale Irrigation District (OID), San Joaquin County No. 1, San Joaquin County No. 2, South Delta Water Agency (SDWA), South San Joaquin GSA (composed of South San Joaquin Irrigation District [SSJID] including Woodward Reservoir, City of Ripon, and City of Escalon), Stockton East Water District (SEWD), and Woodbridge Irrigation District (WID). Collectively, these 16 GSAs will be referred to as “GSAs.” Figure 1-3 below indicates the jurisdictional boundaries of the individual GSAs.

The GSAs represent a diverse range of water management organizations. The agencies include water agencies, irrigation districts, water conservation districts, and local governments at the city and county level. The GSAs work through the ESJGWA to coordinate implementation of the GSP by each GSA to cover the entire geographic extent encompassed by the boundaries of the Eastern San Joaquin Subbasin.

California Water Service Company Stockton District (Cal Water) formed a partnership with San Joaquin County to participate in the process as part of the San Joaquin County No. 2 GSA, since its status as an investor-owned utility prohibited it from forming its own GSA under SGMA regulations until later amendments under SB 13 (Pavley). As a major purveyor of water in the Stockton region, Cal Water’s participation is considered essential to the development and implementation of a comprehensive plan for sustainable groundwater management in the Subbasin.

The portion of the City of Lathrop located east of the San Joaquin River was initially involved in the Eastern San Joaquin Subbasin 2020 GSP development process as a 17th GSA (City of Lathrop GSA) and was part of the ESJGWA. The City of Lathrop GSA voluntarily withdrew its status from the ESJGWA in March 2019 following DWR’s approval of their request for a basin boundary modification between the Eastern San Joaquin Subbasin and the neighboring Tracy Subbasin, which moved the City of Lathrop entirely within the Tracy Subbasin.

WID voluntarily withdrew its status as a GSA and its membership in the ESJGWA in December 2018; WID reinstated its status as a GSA and its membership in the ESJGWA in October 2019.

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Agency Information, Plan Area, and Communication November 2024 Figure 1-3: Eastern San Joaquin Groundwater Sustainability Agencies EXHIBIT 1
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Agency Information, Plan Area, and Communication November 2024

1.1.4.1 Eastern San Joaquin Groundwater Authority Joint Powers Agreement The Joint Powers Agreement (JPA) provides the basis for forming the ESJGWA. The ESJGWA submitted an Initial Notification to jointly develop a GSP for the Eastern San Joaquin Subbasin on February 8, 2017. The agreement and bylaws are provided in Appendix 1-A.

The purpose of the ESJGWA is to act as the coordinating agency and cooperatively carry out the purposes of SGMA in the Eastern San Joaquin Subbasin. The ESJGWA is a public entity separate from the member organizations and holds the authority to coordinate and exercise the common powers of its members within the geographical area of the Eastern San Joaquin Subbasin consistent with the terms and conditions of the JPA.

Since its formation, the ESJGWA has employed a consensus-based approach in its goal to provide a dynamic, costeffective, and collegial organization to achieve initial and ongoing SGMA compliance within the Subbasin. Collaboration among the ESJGWA member agencies has strengthened the potential for broad public support for groundwater management activities as well as the ability to leverage local, state, and federal funds (Eastern San Joaquin GWA, 2017b).

1.1.4.2 Organization and Management Structure of the GSAs The governing body of the ESJGWA, the ESJGWA Board of Directors (ESJGWA Board), convenes every second Wednesday of the month at 10:30 a.m. to coordinate efforts to implement the GSP by debating and finalizing key discussion points and decisions incorporated into the Plan. Each of the 16 GSAs has a voice on the ESJGWA Board and has appointed two representatives to serve: one Board member and one Alternate member to attend in the Board member’s absence.

The ESJGWA Board is tasked with developing actions including, but not limited to, the following:
• Approving budget(s) and appropriate cost sharing for any project or program that requires funding from the ESJGWA
• Proposing guidance and options for obtaining grant funding • Adopting rules, regulations, policies, and procedures related to the JPA • Approving any contracts with consultants or subcontractors that would undertake work on behalf of the GSAs and/or relate to Basin-wide issues and, if applicable, recommend the funding that each GSA should contribute towards the costs of such contracts
• Reporting to the GSA’s respective governing boards
• Approving and implementing a GSP
The ESJGWA Board is guided by a Steering Committee that is made up of one representative from each GSA and convenes every second Wednesday of the month at 8:30 a.m. The Steering Committee is responsible for developing recommendations on technical and substantive Subbasin-wide matters. The Steering Committee is tasked with developing actions including, but not limited to, the following:
• Recommending the action and/or approval of technical or policy elements for the implementation of the GSP, including groundwater conditions, thresholds, and projects and management actions • Recommending the action and/or approval of a GSP
To support the 5-year Periodic Evaluation of the GSP and development the 2024 GSP Amendment, the Steering Committee recommended that the chair of the ESJGWA form an Ad Hoc Project Management Committee (PMC).

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Agency Information, Plan Area, and Communication November 2024 Approved by the Steering Committee in December 2023, the PMC was comprised of six GSA volunteers representing the varied interests in the Subbasin and covering both urban and agricultural areas. At the time of the development of the 2024 GSP Amendment, the six members of the PMC represented the following GSAs: City of Stockton, North San Joaquin Water Conservation District, Oakdale Irrigation District, San Joaquin County, South San Joaquin Irrigation District, and Stockton East Water District. The PMC met bi-monthly during the GSP Periodic Evaluation and GSP amendment process, and was tasked with driving the review and update process and coordinating other SGMA implementation efforts, including development of a Well Mitigation Program, coordination of stakeholder outreach and engagement, and annual and long-term budgeting. PMC members reviewed draft work products and other meeting materials to provide input and direction as needed at the bi-monthly meetings. The PMC was also responsible for recognizing and flagging items requiring discussion and direction from stakeholders, the Steering Committee, and the ESJGWA. While the PMC informed administrative concepts and reviewed draft work products at the staff level, they did not have decision-making authority.

Decisions of the ESJGWA Board are made by an affirmative majority of Board members, except in the following cases which require a two-thirds supermajority vote: approval or modification or amendment of the ESJGWA annual budget; decisions related to the levying of taxes, assessments, or property-related fees and charges; decisions related to the expenditure of funds by the ESJGWA beyond expenditures approved in the annual budget; adoption of rules, regulations, policies, bylaws, and procedures related to the function of the ESJGWA; decisions related to the establishment of the members’ percentage obligations for payment of the ESJGWA’s operating and administrative costs; approval of any contract over $250,000 or contracts for terms that exceed two years; decisions regarding the acquisition and the holding, use, sale, letting, and disposal of real and personal property including water rights, and the construction, maintenance, alteration, and operation of works or improvements; decisions related to the limitation or curtailment of groundwater pumping; and approval of a GSP. Each member of the ESJGWA Board has one vote. A process for dispute resolution and noncompliance, including internal resolution and mediation prior to judicial or administrative remedies, is set forth in the ESJGWA Bylaws in Appendix 1-A.

GSAs share in the general operating and administrative costs of the ESJGWA in accordance with percentages determined by the ESJGWA Board.

1.1.4.3 Description of Participating Agencies
A brief description of each of the GSAs that make up the ESJGWA is provided in the sections below.

Central Delta Water Agency – The Central Delta Water Agency (CDWA) service area encompasses a total of 52,000 acres in the northwestern portion of the Eastern San Joaquin Subbasin. The primary land use in this area is agriculture with crops such as vineyards, fruit and nut trees, row crops, and field crops. CDWA protects water supply within its service area (which extends outside of the Subbasin), assists landowners and reclamation districts with water issues, and represents landowners in flood control matters. CDWA does not own any facilities, and surface water from the Delta is the area’s only utilized source of water, along with limited private groundwater pumping. Approximately 5,000 acres of the GSA overlap with the sphere of influence of the City of Stockton (Eastern San Joaquin County GBA, 2014).

Central San Joaquin Water Conservation District – The Central San Joaquin Water Conservation District (CSJWCD) was formed in 1959 under provisions of the California Water Conservation Act of 1931. The CSJWCD includes approximately 73,000 largely agricultural acres, of which 6,300 acres are within the sphere of influence of the City of Stockton. To mitigate declining groundwater levels, the CSJWCD contracted with the United States Bureau of Reclamation (USBR) for 80,000 acre‐feet per year (AF/year) from New Melones Reservoir on the Stanislaus River.

Irrigation facilities have been installed and operated by individual landowners through a surface water incentive program sponsored by the CSJWCD. At the regional level, CSJWCD has participated as a member agency of the Eastern Water Alliance and the Groundwater Basin Authority (GBA), two preceding efforts to the ESJGWA that focused on groundwater management (Eastern San Joaquin County GBA, 2014).

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2024 Groundwater Sustainability Plan Amendment 1-7
Agency Information, Plan Area, and Communication November 2024 City of Lodi – The City of Lodi is located northeast of the City of Stockton along Highway 99. The City of Lodi relies on both groundwater and surface water to satisfy customer needs. In 2003, Lodi entered into a 40‐year agreement with WID for up to 6,000 AF/year of Mokelumne River water. The City of Lodi built the Lodi Surface Water Treatment Plant and associated conveyance facilities necessary to deliver this supply, which were completed and operational at the end of 2012. The City of Lodi currently provides up to 3,000 AF/year of treated wastewater to agricultural land in the vicinity of the wastewater treatment plant, White Slough Water Pollution Control Facility. The GSA for the City of Lodi covers 9,000 acres and includes the White Slough Water Pollution Control Facility area (City of Lodi, 2015).

City of Manteca – The City of Manteca’s approximately 13,000 acres straddles Highway 99 south of the City of Stockton. Potable water supplies consist of a combination of groundwater and treated surface water from the South County Water Supply Program (SCWSP). Manteca currently receives up to 11,500 AF/year of treated surface water and ultimately can receive up to 18,500 AF/year in Phase II of the SCWSP. Up to 700 AF/year of reclaimed wastewater is applied to fodder crops on City-owned and leased lands (City of Manteca, 2020).

City of Stockton – The City of Stockton Municipal Utilities Department (MUD) service area generally encompasses portions of the City of Stockton north of the Calaveras River and south of the Cal Water service area. Water use measured in 2015 shows approximately 27 percent of the Stockton MUD’s water deliveries come from groundwater, with 73 percent from treated surface water from SEWD and the Delta Water Supply Project. The Delta Water Supply Project came online in 2012 and utilizes surface water both from the San Joaquin River (City of Stockton water right) and Mokelumne River through a 40-year agreement with WID initiated in 2008 for up to 6,500 AF/year with more water as the City of Stockton grows. The City of Stockton GSA (approximately 39,000 acres) overlaps with the extent of the Cal Water service area (City of Stockton, 2015).

Eastside San Joaquin GSA – Eastside San Joaquin GSA (Eastside GSA) is a partnership between Calaveras County Water District, Calaveras County, Stanislaus County, and Rock Creek Water District. The area covers over 126,000 acres, stretching into the western portion of Calaveras County and northern portion of Stanislaus County. • Calaveras County Water District – The Calaveras County Water District (CCWD) provides water service to approximately 13,360 municipal and residential customers in six service areas and shares the same boundaries as Calaveras County. Supply for CCWD comes from reservoir releases on the Calaveras, Stanislaus, and Mokelumne Rivers for a total of approximately 6,000 AF/year for primarily agricultural and residential use. CCWD has several customers with riparian rights along the Calaveras River, has one service area that relies solely on groundwater, and has several areas that utilize recycled water. • Calaveras County – Calaveras County has a total area of 1,037 square miles and extends beyond the boundaries of the Eastern San Joaquin Subbasin. Calaveras County Water District is the only public water supplier to residents located in the portion of the County overlying the Subbasin. The only incorporated city, Angels Camp, is located outside of the Subbasin. Calaveras County had one of the fastest growing annual percent increases in population in California between 2000 and 2010 (CCWD, 2020). For the portion of Calaveras County that falls within the Eastern San Joaquin Subbasin, there are numerous domestic, municipal, and monitoring wells.
• Stanislaus County – Stanislaus County has a total area of 973,000 acres and nine incorporated cities and extends beyond Eastern San Joaquin Subbasin. There are approximately 30 water suppliers that serve water to Stanislaus County for domestic, commercial, and agricultural uses. The majority of the county’s population resides in incorporated cities due to urban development and steady population growth within city boundaries.

These incorporated cities are outside of the Subbasin. The portions of Stanislaus County that fall within the Eastern San Joaquin Subbasin not already included in a GSA have partnered with CCWD, Calaveras County, and Rock Creek Water District as the Eastside GSA. The land is mostly unirrigated, and water needs are met by private pumping.

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2024 Groundwater Sustainability Plan Amendment 1-8
Agency Information, Plan Area, and Communication November 2024 • Rock Creek Water District – Rock Creek Water District was formed in 1941 and covers approximately 1,800 acres in northeastern Stanislaus County. Through the Salt Spring Valley Reservoir in Calaveras County, Rock Creek Water District delivers agricultural water for irrigation (Stanislaus LAFCO, 2018).

Linden County Water District – Linden County Water District (LCWD) provides water and wastewater services to the 300 acres of the unincorporated community of Linden. LCWD is located approximately 12 miles northeast of the City of Stockton along State Route 26. LCWD lies entirely within the boundaries of the SEWD. Between 2000 and 2010, the population in Linden increased by 61 percent from approximately 1,100 to 1,800 residents. LCWD relies on groundwater to meet residential demands in Linden (SJC, 1992).

Lockeford Community Services District – Lockeford Community Services District (LCSD) was established in 1976 and superseded the San Joaquin County Water Works District No. 1 and Lockeford Sanitary District. LCSD provides water and wastewater services to approximately 3,200 residents (as of 2010) in the unincorporated urban community of Lockeford located 17 miles northeast of the City of Stockton on State Routes 12 and 88. LCSD lies within the boundaries of the NSJWCD; however, LCSD’s jurisdiction area is its own GSA and is not part of the NSJWCD GSA.

LCSD’s GSA area is approximately 800 acres and encompasses primarily residential and commercial uses. LCSD anticipates that, as community build-out occurs, it may serve over 5,000 residents. Groundwater from the Eastern San Joaquin Subbasin is LCSD’s only source of potable water (SJC, 2016a).

North San Joaquin Water Conservation District GSA – North San Joaquin Water Conservation District (NSJWCD), organized in 1948 under provisions of the Water Conservation District Act of 1931, includes approximately 149,000 acres east of the City of Lodi, including about 70,000 acres of irrigated agriculture. NSJWCD also includes approximately 4,740 acres within the Lodi city limits and the community of Lockeford. Pursuant to agreements between NSJWCD, Lockeford, and Lodi, the Lodi and Lockeford acreage is excluded from the NSJWCD GSA. NSJWCD straddles the Mokelumne River and has Dry Creek as its northern boundary. Prior to a basin boundary modification approved in 2016, NSJWCD was located in both the Cosumnes and the Eastern San Joaquin Subbasins. NSJWCD has a 20,000 AF Mokelumne River surface water right which is generally available in normal to wet years. NSJWCD provides surface water deliveries to irrigated acreage and conducts groundwater recharge, but much of the NSJWCD area relies on private groundwater pumping. At the regional level, NSJWCD has participated as a member agency of the Eastern Water Alliance and the GBA, two preceding efforts to the ESJGWA that focused on groundwater management (Eastern San Joaquin County GBA, 2014).

Oakdale Irrigation District – Oakdale Irrigation District (OID) comprises about 81,000 acres, primarily located in the northern portion of Stanislaus County, but with a small portion located within San Joaquin County. A little less than 40 percent of the District’s area overlies the Eastern San Joaquin Subbasin (over 31,000 acres), and the remaining portion overlies the Modesto Subbasin. SSJID and OID jointly own facilities to provide water from the Stanislaus River for agricultural use (Eastern San Joaquin County GBA, 2014).

San Joaquin County – The San Joaquin County GSA consists of 51,000 acres of areas within the Eastern San Joaquin Subbasin not covered by the other GSAs. Overlapping agencies include North Delta Water Agency (NDWA), unincorporated county, riparian land along Stanislaus River, and areas in the City of Stockton served by the City of Stockton MUD. In collaboration with the Northeast San Joaquin County Groundwater Banking Authority, San Joaquin County led the development of the Eastern San Joaquin Groundwater Basin Groundwater Management Plan in 2004 to review, enhance, and coordinate existing groundwater management policies and programs in the region and to develop new policies and programs for the long-term sustainability of groundwater resources. San Joaquin County has also supported the development of studies and plans in the region, such as the Groundwater Basin Authority System Plan and San Joaquin County Water Management Plan.
• North Delta Water Agency – The NDWA was formed by a special act of the Legislature in 1973 to protect the water supply against seawater intrusion and to ensure a reliable water supply to meet current and future water needs. The NDWA service area now includes approximately 277,000 acres within the counties of Sacramento, San Joaquin, Solano, and Yolo. Most of the land is devoted to agriculture use and supplied with surface water EXHIBIT 1
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2024 Groundwater Sustainability Plan Amendment 1-9
Agency Information, Plan Area, and Communication November 2024 from the Delta (NDWA, 2015). The reclamations districts within the NDWA and the Eastern San Joaquin Subbasin include Reclamation District (RD) 38 – Staten Island, RD 2086 – Canal Ranch, and RD 348 – New Hope Tract.

San Joaquin County No. 2 (Cal Water) – San Joaquin County No. 2 GSA includes approximately 7,000 acres of the unincorporated San Joaquin County portion of the Cal Water Service Area. Cal Water is an investor-owned public utility regulated by the California Public Utilities Commission; it is a signatory to the California Urban Water Conservation Council. Cal Water has approximately 42,000 connections in the greater Stockton area, primarily south of the Calaveras River. Cal Water utilizes surface water delivered from SEWD and groundwater pumped by Cal Water wells to meet customer demands. Cal Water's Stockton District was formed in 1927 with the purchase of the water system from Pacific Gas and Electric Company (PG&E).

South Delta Water Agency – The South Delta Water Agency (SDWA) was originally formed to address local water supply and water quality concerns in the south Delta area. The SDWA encompasses a total of approximately 150,000 acres within its boundaries, and almost 18,000 acres overlap with the southwestern portion of the Eastern San Joaquin Subbasin. The SDWA does not own any facilities or water rights. Instead, the SDWA protects property owners who have individual water rights. Surface water is the primary source of water used within the agency boundaries given that most of the groundwater is highly saline (Eastern San Joaquin County GBA, 2014).

South San Joaquin GSA – South San Joaquin GSA’s 64,000 acres encompass most of the South San Joaquin Irrigation District (SSJID), including Woodward Reservoir and canals leading to SSJID; the City of Ripon; and the City of Escalon. The portion of SSJID within the incorporated City of Manteca is included in the City of Manteca GSA. • South San Joaquin Irrigation District – SSJID was formed in 1909 under the Irrigation District Act and covers approximately 72,000 acres in the southeastern portion of San Joaquin County located within the Eastern San Joaquin Subbasin boundaries. The cities of Manteca, Ripon, and Escalon account for approximately 20,000 acres of the SSJID area. SSJID in 2005 began the delivery of up to 32,000 AF/year currently (and up to 43,000 AF/year in Phase II) of treated surface water from Woodward Reservoir to the cities of Manteca, Lathrop, and Tracy for the SCWSP, with Escalon to receive water in the future (Eastern San Joaquin County GBA, 2014).
• City of Ripon – The City of Ripon is located at the southern edge of San Joaquin County along Highway 99.

The population in 2015 was approximately 16,000 people and is expected to grow to about 30,800 people by 2040 (U.S. Census Bureau, 2020). The city’s potable water is provided by city groundwater wells and supplied over 4,000 acre-feet (AF) in 2015. Non-potable groundwater and surface water from SSJID are used for irrigation purposes and recharge (City of Ripon, 2015). • City of Escalon – The City of Escalon is located within the San Joaquin County boundaries along State Route 120. Incorporated in 1957, the City of Escalon was home to approximately 7,400 residents in 2020 (U.S.

Census Bureau, 2020). The City of Escalon has an allotment of 2,015 AF of treated water from the SSJID and the SCWSP; however, the city is not utilizing its allotment and currently relies solely on groundwater wells to serve the city’s population as well as commercial customers. The City of Escalon is selling its allotment of treated water to the City of Tracy but intends to construct a pipeline to convey SSJID water to meet domestic and industrial needs in the City of Escalon (SSJID, 2015b).

Stockton East Water District – Stockton East Water District (SEWD) was formed in 1948, includes a total of 143,300 acres, overlaps with portions of WID, and includes the entire City of Stockton and the entire Cal Water service area. The SEWD GSA covers 101,000 acres of the district, with the remaining SEWD areas covered by the City of Stockton, San Joaquin County, and San Joaquin County No. 2 GSAs. SEWD is guaranteed 56.5 percent of New Hogan Reservoir’s yield and is provided a total amount of 75,000 AF/year from New Melones Reservoir through agreements with USBR. SEWD delivers wholesale drinking water to the City of Stockton, Cal Water, San Joaquin County, and Woodbridge Irrigation District (WID) areas in the Stockton MUD (Eastern San Joaquin County GBA, 2014). At the EXHIBIT 1
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2024 Groundwater Sustainability Plan Amendment 1-10
Agency Information, Plan Area, and Communication November 2024 regional level, SEWD has participated as a member agency of the Eastern Water Alliance and the GBA, two efforts preceding the current ESJGWA that focused on groundwater management (Eastern San Joaquin County GBA, 2014).

Woodbridge Irrigation District – WID, organized in 1924 under the California Irrigation District Act, encompasses a gross area of approximately 42,900 acres with over 29,000 acres covered by the WID GSA. WID is discontiguous, resulting in patches of non‐district lands within its boundary, and overlaps with portions of NSJWCD, SEWD, and the City of Lodi. WID owns and operates the Woodbridge Diversion Dam, located on the Lower Mokelumne River northeast of the City of Lodi, as well as an extensive canal system serving approximately 13,000 acres west of Lodi and north of Stockton. Recent improvements made to the new Woodbridge Diversion Dam include state‐of‐the‐art fish and diversion works which enable WID to keep Lodi Lake full year‐round. At the regional level, WID has participated as a member agency in regional groundwater management efforts, including the GBA.

1.1.4.4 Legal Authority
Any local public agency that has water supply, water management, or land use responsibilities in a basin can decide to become a GSA under SGMA. A single local agency can become a GSA, or a combination of local agencies can decide to form a GSA by using either a JPA, a memorandum of agreement (MOA), or other legal agreement (CA DWR, 2016a).

In the Eastern San Joaquin Subbasin, the ESJGWA has legal authority to jointly prepare, adopt, and implement a GSP consistent with the terms of the JPA Agreement and the ESJGWA Bylaws (Eastern San Joaquin GWA, 2017a). The ESJGWA's JPA calls out the following powers granted to GSAs by SGMA:
• Become a GSA individually or collectively;
• Approve any portion, section, or chapter of the GSP adopted by the ESJGWA; • Act through GSAs to implement SGMA and the GSP; and
• Exercise the powers conferred to GSAs by SGMA.

Each GSA that is a member of the ESJGWA has its own legal authorities. For example, NSJWCD has the legal authorities granted to a GSA under the California Water Code (Water Code) as well as the legal authorities granted to a Water Conservation District pursuant to Water Code § 74000 et seq. The legal authorities of each GSA are listed in Appendix 1-B. Agency resolutions to become GSAs are provided in Appendix 1-C.

1.1.4.5 Estimated Costs and Approach to Meeting Costs
Implementation of the GSP requires funding sources. To the degree they become available, outside grants will be sought to assist in reducing the cost of implementation to participating agencies, residents, and landowners of the Subbasin. However, there will be a need to collect funds to support implementation.

For budgetary purposes, the estimated initial cost of these activities is on the order of $600,000 to $1 million per year excluding projects and management actions costs and costs associated with the installation of new monitoring wells and grant writing. Additional one-time costs, such as model refinement, are estimated to be on the order of $315,000.

The ESJGWA Board will evaluate options for securing the needed funding. Additional detail on GSP implementation costs and funding sources are detailed in Chapter 7: Plan Implementation.

1.1.5 GSP Organization
This GSP is organized according to DWR’s “GSP Annotated Outline” for standardized reporting (CA DWR, 2016b).

The Preparation Checklist for GSP Submittal in DWR formatting can be found in Appendix 1-D (CA DWR, 2016d).

1.2 PLAN AREA
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Agency Information, Plan Area, and Communication November 2024

1.2.1 Description of Plan Area
This section provides a detailed description of the Eastern San Joaquin Subbasin, including major streams and creeks, institutional entities, agricultural and urban land uses, locations of groundwater wells, and locations of state lands. The Plan Area document also describes existing surface water and groundwater monitoring programs, existing water management programs, and general plans in the Plan Area.

1.2.1.1 Summary of Jurisdictional Areas and Other Features The Eastern San Joaquin Subbasin falls within the larger San Joaquin Valley Groundwater Basin (see Figure 1-4).

Basin designations by DWR were first published in 1952 in Water Quality Investigations Report No. 3, Ground Water Basins in California, and subsequently updated in Bulletin 118 in 1975, 1980, 2003, and 2020. The San Joaquin River Hydrologic Region contains 11 distinct subbasins, where the Eastern San Joaquin Subbasin (Bulletin 118 Basin Number 5-022.01) is bordered to the north by the Cosumnes Subbasin (Bulletin 118 Basin Number 5-022.16), the South American Subbasin (Bulletin 118 Basin Number 5-021.65), and the Solano Subbasin (Bulletin 118 Basin Number 5-021.66); to the south by the Modesto Subbasin (Bulletin 118 Basin Number 5-022.02); and to the west by the Tracy Subbasin (Bulletin 118 Basin Number 5-022.15) and East Contra Costa Subbasin (Bulletin 118 Basin Number 5-022.19) (see Figure 1-5).

The Eastern San Joaquin Subbasin includes lands south of Dry Creek between the San Joaquin River on the west and the crystalline basement rock of the Sierra Nevada foothills on the east. The Eastern San Joaquin Subbasin boundary to the south stretches along the San Joaquin County line and continues along the Stanislaus River into Calaveras County to the east. Geologic units in the Eastern San Joaquin Subbasin consist of consolidated rocks and unconsolidated deposits (CA DWR, 2006).

No adjudicated areas or areas covered by an alternative to a GSP exist within the Eastern San Joaquin Subbasin.

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2024 Groundwater Sustainability Plan Amendment 1-12
Agency Information, Plan Area, and Communication November 2024 Figure 1-4: Placement within the San Joaquin Valley Groundwater Basin EXHIBIT 1
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Agency Information, Plan Area, and Communication November 2024 Figure 1-5: Neighboring Groundwater Subbasins
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Agency Information, Plan Area, and Communication November 2024 The Eastern San Joaquin Subbasin underlies areas of San Joaquin, Stanislaus, and Calaveras Counties. Figure 1-6 shows the location of these three counties within the State of California as well as the three other counties bordering the Eastern San Joaquin Subbasin: Sacramento, Amador, and Contra Costa.

Figure 1-6: Underlying and Surrounding Counties
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Agency Information, Plan Area, and Communication November 2024 Figure 1-7 shows the Eastern San Joaquin Subbasin and the Subbasin’s key geographic features. The Subbasin encompasses an area of about 1,195 square miles. There are eight entities within the region with land use jurisdiction:
the County of San Joaquin, the County of Calaveras, the County of Stanislaus, the City of Stockton, the City of Lodi, the City of Manteca, the City of Escalon, and the City of Ripon. The cities of Lodi, Escalon, Manteca, and Ripon are contained entirely within the Subbasin, while western portions of San Joaquin County and the City of Stockton, and eastern portions of Calaveras and Stanislaus counties lie in neighboring subbasins or outside of groundwater subbasins altogether. The Eastern San Joaquin Subbasin encompasses the following unincorporated communities:

Acampo, Adela, Atlanta, August, Bear Creek, Burson, Clements, Collierville, Country Club, Dogtown, East Oakdale, Eugene, Farmington, French Camp, Garden Acres, Goodmans Corner, Jenny Lind, Kennedy, Knights Ferry, Lake Camanche Ranches, Lincoln Village, Linden, Lockeford, Milton, Morada, Mormon, Oak Grove, Peters, South Camanche Shore, Taft Mosswood, Terminous, Thornton, Valley Home, Valley Springs, Victor, Wallace, Waterloo, Woodbridge, and Youngstown.

Figure 1-7: City Boundaries
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Agency Information, Plan Area, and Communication November 2024 Figure 1-8 shows the spatial extent of Disadvantaged Communities (DACs) and Severely Disadvantaged Communities (SDACs) in the Eastern San Joaquin Subbasin. DWR defines DACs as census geographies (census tracts, census block groups, and census-designated places) with an annual median household income (MHI) that is less than 80 percent of the statewide annual MHI. SDACs are defined as census geographies with an MHI less than 60 percent of the statewide annual MHI. DWR uses the most recently available 5-year American Community Survey (ACS) dataset to identify these areas. For this GSP, the 2016-2020 ACS dataset was used, establishing statewide MHI as $78,672 (CA DWR, Mapping Tools).

Figure 1-8: Disadvantaged Communities (DACs)
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Agency Information, Plan Area, and Communication November 2024 Figure 1-9 shows a map of land use in the Eastern San Joaquin Subbasin across four general categories: cropland, industrial, undeveloped, and urban. These categories were mapped based on categories identified from the United States Department of Agriculture’s (USDA) CropScape 2022 dataset.

Land use patterns in the Eastern San Joaquin Subbasin are dominated by agricultural uses, including nut and fruit trees, vineyards, row crops, grazing, and forage. Both agricultural and urban land use rely on a combination of surface water and groundwater, with some agricultural lands using recycled or reusing water. Land use is primarily controlled by local agencies. Land use patterns in the low foothills to the east are dominated by native vegetation and unirrigated pasture lands (USDA, 2022).

Figure 1-9: Land Use
Crop type varies by region, with fruit and nut trees and vine crops comprising the majority of agriculture in the Subbasin.

Almond orchards dominate the southern portion of the Subbasin, cherry and walnut orchards dominate the central portion of the Subbasin, and vineyards dominate the northern portion (Figure 1-10). Irrigated crop acreage in the Subbasin are 37 percent fruit and nut trees, 24 percent vineyards, and 11 percent alfalfa and irrigated pasture, according to the 2022 CropScape dataset (USDA, 2022).

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Agency Information, Plan Area, and Communication November 2024 Figure 1-10: Land Use by Crop Type
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Agency Information, Plan Area, and Communication November 2024 Figure 1-11 shows a map with boundaries of federal and state public lands within the region that includes the Eastern San Joaquin Subbasin. The United States Fish and Wildlife Service (USFWS) manages the San Joaquin River National Wildlife Refuge situated in Stanislaus County where the Tuolumne, Stanislaus, and San Joaquin rivers meet.

Established in 1987 to provide habitat for migratory birds and endangered species, the refuge is 7,000 acres and is located just outside the southern boundary of the Subbasin (USFWS, 2012).

The California Department of Parks and Recreation maintains the Caswell Memorial State Park located along the Stanislaus River near Ripon (California State Parks, 2019). The Caswell Memorial State Park protects a riparian oak woodland and is home to the riparian brush rabbit, an endangered species (California State Parks, 2019). This is the only state park within the Eastern San Joaquin Subbasin boundary. The Franks Tract State Recreation Area (SRA) and the Carnegie State Vehicular Recreation Area (SVRA) are also managed by California State Parks; however, both of these areas are located outside of the Subbasin boundary.

The California Department of Fish and Wildlife (CDFW) owns 880 acres of man-made ditches, canals, and marshes with both grassland and riparian habitat, recognized as the White Slough Wildlife Area. The property was designated by the Fish and Game Commission in 1980 and provides recreational opportunities such as fishing, hunting, and hiking (CDFW, 2019a). CDFW also maintains the 353-acre Woodbridge Ecological Reserve to protect primarily the sandhill crane population, but also other migratory waterfowl. The sandhill crane was listed as a threatened species in 1983.

Woodbridge Ecological Reserve and the greater Stockton Delta wetlands make up the largest freshwater marsh in California (CDFW, 2019b). Lastly, Vernalis Ecological Reserve is also shown in Figure 1-11. It serves as a public access area owned by CDFW for hunting and wildlife viewing (CDFW, 2019c).

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Agency Information, Plan Area, and Communication November 2024 Figure 1-11: US Fish and Wildlife Service, California State Parks, and California Department of Fish and Wildlife Boundaries
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Agency Information, Plan Area, and Communication November 2024 Figure 1-12 to Figure 1-14 shows the density, as of 2019, of domestic, public, and production wells per square mile in the Eastern San Joaquin Subbasin, as classified by the DWR Online System for Well Completion Reports (OSWCR), which is discussed in Section 1.2.2.1. This includes approximately 1,000 unique wells collected primarily from DWR’s Water Data Library (WDL), but also other state, regional, and local monitoring entities (CA DWR, n.d.). Though there are overlaps and discrepancies in the designation of wells, domestic wells are largely private residential wells, public wells are municipal-operated wells, and production wells are for irrigation, municipal, public, and industrial purposes (CA DWR, 2019). Areas with few wells exist in the Subbasin, particularly in the northwestern corner of the Subbasin and to the east. Wells containing groundwater level data are described further in Section 1.2.2.1. Community water systems, defined by the State Water Resources Control Board (SWRCB) as wells serving 15 or more connections or more than 25 people per day, are identified in Appendix 1-E. Appendix 1-E contains additional detail on where community water systems are found in the Subbasin.

Figure 1-12: Density of Domestic Wells per Square Mile
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Agency Information, Plan Area, and Communication November 2024 Figure 1-13: Density of Public Wells per Square Mile
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Agency Information, Plan Area, and Communication November 2024 Figure 1-14: Density of Production Wells per Square Mile

1.2.2 Water Resources Monitoring and Management Programs The existing monitoring and management landscape within the Eastern San Joaquin Subbasin is a patchwork of local, regional, state, and federal programs, each serving its own specific function. This patchwork provides valuable data that have supported past needs and will assist in meeting monitoring needs under SGMA. This patchwork of programs includes redundancies, inconsistent protocols, and inconsistent timing of monitoring that may be improved during SGMA implementation.

Existing monitoring within the Eastern San Joaquin Subbasin is extensive, complex, and performed for a variety of purposes by a variety of entities. During a review of existing groundwater monitoring data and programs, data were collected from the following agencies and programs. Programs and agencies are listed by the jurisdiction they operate across: statewide, regional, or local. The sections that follow describe in detail the programs most heavily relied upon in the development of the GSP and are organized by data type. Section 1.2.2.3 addresses the interconnection between databases.

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Agency Information, Plan Area, and Communication November 2024 Statewide Monitoring Programs (Agencies and Databases):
• California Data Exchange Center (CDEC)
• California Department of Pesticide Regulation (CDPR)
• California Environmental Data Exchange Network (CEDEN) • California State Water Resources Control Board (SWRCB), Division of Drinking Water (DDW) • Department of Water Resources (DWR):
o Airborne Electromagnetic (AEM) Surveys
o California Statewide Groundwater Elevation Monitoring (CASGEM) o California Statewide Groundwater Elevation Monitoring Groundwater Information Center Interactive Mapping Application (GICIMA)
o Online System for Well Completion Reports (OSWCR)
o Water Data Library (WDL)
• Groundwater Ambient Monitoring and Assessment (GAMA) Program • GeoTracker
• University NAVSTAR Consortium (UNAVCO)
• United States Bureau of Reclamation (USBR)
• United States Geological Survey (USGS)
Regional Monitoring Programs:
• Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS) • California Department of Public Health (CDPH)
• Central Valley Regional Water Quality Control Board (CVRWQCB) Waste Discharge Requirement (WDR) dairy data, Dairy Cares
• USGS’s National Water Information System (NWIS)
• Central Valley Dairy Representative Monitoring Program • EnviroStor
• Groundwater Quality Trend Monitoring Program through SWRCB Irrigated Lands Regulatory Program (ILRP) • San Joaquin River Restoration Program
Local Monitoring Agencies
• Cal Water
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Agency Information, Plan Area, and Communication November 2024 • Calaveras County Water District
• City of Lodi
• City of Manteca
• City of Stockton
• Linden County Water District
• Lockeford Community Services District
• North San Joaquin Water Conservation District
• Oakdale Irrigation District
• San Joaquin County
• South San Joaquin Irrigation District
• Stockton East Water District
A description of the monitoring programs that will be used in GSP implementation is provided in Chapter 4: Monitoring Networks.

1.2.2.1 Groundwater Level Monitoring and Data Sources

1.2.2.1.1 CASGEM
DWR maintains several groundwater level monitoring programs, tools, and resources covering California. The California Statewide Groundwater Elevation Monitoring (CASGEM) Program is DWR’s primary resource for groundwater level data and has been used extensively in the development of this GSP. The CASGEM Program was authorized in 2009 by SB X7-6 to establish collaboration between local monitoring parties and DWR to collect and make public statewide groundwater elevation data. The program provides the framework for local agencies or other organizations to “assume responsibility for monitoring and reporting groundwater elevations in all or part of a basin or subbasin” (Water Code §10927). As part of SGMA implementation, wells that are in the Subbasin’s representative monitoring network have been migrated out of CASGEM and into SGMA; all other pre-existing CASGEM wells remain in that program under voluntary monitoring status.

Three CASGEM monitoring entities exist in the Eastern San Joaquin Subbasin: CCWD, San Joaquin County Flood Control and Water Conservation District (SJCFCWCD), and Stanislaus County. These three agencies have completed separate CASGEM Monitoring Plans, which are included in the references section. • CCWD CASGEM Monitoring Plan: CCWD adopted a CASGEM Monitoring Plan in November 2012, with the following objectives:
o Collect semi-annual groundwater levels from a selected monitoring well network o Upload groundwater levels to the CASGEM website after data quality steps have been completed o Maintain and update the monitoring well network plan documents including additions and removals from the monitoring network
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Agency Information, Plan Area, and Communication November 2024 These objectives are helpful to this planning effort, as they include regular monitoring of groundwater levels and data upload to CASGEM. The CCWD plan also includes a description of the CASGEM monitoring network and groundwater level measurements. The monitoring network includes two USGS nested monitoring wells equipped with pressure transducers, which continuously monitor groundwater levels. The monitoring network also includes seven other wells that are not USGS wells. These wells are not equipped with pressure transducers, and manual groundwater elevation measurements are taken at all wells twice a year. As stated in the CCWD CASGEM plan, the non-USGS wells are owned by private landowners, and additional wells may need to be added in the future if owners opt out of the monitoring network (CCWD, 2012). This monitoring network covers the portion of Calaveras County within the Eastern San Joaquin Subbasin. • SJCFCWCD CASGEM Monitoring Plan: The SJCFCWCD CASGEM Monitoring Plan provides a description of the CASGEM monitoring network and groundwater conditions in San Joaquin County. This plan covers the portions of the Eastern San Joaquin and Tracy Subbasins within San Joaquin County. The SJCFCWCD has been taking semi-annual water level measurements since 1971 at wells owned by a variety of entities and by private individuals. A large portion of wells in the district’s network are privately owned (SJCFCWCD, 2006).

SJCFCWCD sent out consent forms to these private well owners to release well information to CASGEM; about 40 of these forms were signed and returned, and construction information for these wells was uploaded to CASGEM. This information includes attributes such as well depth, coordinates, reference point elevation, and depth of screened interval.
• Stanislaus County CASGEM Monitoring Plan: The Stanislaus County Department of Environmental Resources (DER) established a CASGEM monitoring plan in 2016 to cover the portion of Stanislaus County within the Eastern San Joaquin Subbasin, often referred to as the northern triangle. This plan details the groundwater level monitoring history, protocols, and network for the northern triangle portion of Stanislaus County. This area is rural and most of the development exists between the Stanislaus River and near the Woodward Reservoir. Wells selected for the CASGEM program are in the developed areas. 17 wells are included in this CASGEM plan to be measured semi-annually, consisting of one domestic and ten irrigation wells, plus six wells that are of unknown type. Well information such as depth and screened interval was uploaded to CASGEM for these wells (Stanislaus County DER, 2016).

1.2.2.1.2 San Joaquin County Flood Control and Water Conservation District The SJCFCWCD publishes semi-annual groundwater reports covering groundwater conditions in San Joaquin County.

These reports include tables, hydrographs, and maps on groundwater levels. Groundwater level results from each semi-annual report are compared with values from the previous period. Groundwater level data collected by the district include the data mentioned in the CASGEM section, above, and additional data that are not incorporated into CASGEM.

The data are maintained by the SJCFCWCD.

1.2.2.1.3 Water Data Library
DWR’s WDL contains measurements of groundwater elevations from water supply and monitoring wells monitored by numerous entities, such as DWR and local agencies. Groundwater level measurements available from the WDL are either continuously or periodically measured. Continuous measurements are provided by automatic water level measuring devices that take readings at wells; periodic measurements are manual recordings typically occurring at monthly or semi-annual time intervals. Measurements displayed through the WDL are taken through other programs, such as CASGEM. The WDL lists the organization responsible for collecting each water level measurement. The WDL water level measurements are available through the California Natural Resources Agency (CNRA) Open Data website as a bulk download, or through the WDL website on a per station basis.

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1.2.2.1.4 USGS – National Water Information System
The NWIS is a USGS program comprising several water datasets, including groundwater level measurements, river flow, and river stage data. Like the WDL, NWIS contains continuous and periodic water measurements for recent and historical conditions. Within the Eastern San Joaquin Subbasin, there are only a few active NWIS sites and many inactive sites with historical records. For stream measurements, active sites are largely along major streams, such as the Mokelumne River, the Stanislaus River, and the San Joaquin River; along Delta waterways; or in the Sierra Nevada foothills, upstream of reservoirs.

1.2.2.1.5 Data Received Directly from GSAs
A number of the GSAs collect water level and water quality information within their GSAs at varying frequencies and detail. These data were provided as part of the Eastern San Joaquin Water Resources Model (ESJWRM) data collection efforts and were compared with and included in groundwater level and water quality datasets analyzed for updates to the ESJWRM model and the preparation of this GSP.

The development and update of the ESJWRM took place in an open and transparent process. Coordination efforts took place through the Eastern San Joaquin County GBA, the organizational structure for agency coordination that proceeded SGMA regulations and the formation of the ESJGWA, and through the Subbasin Steering Committee.

Through this effort, many of the staff and consultants representing the GSAs forming the ESJGWA participated as a forum to review model input data and assumptions. The group facilitated major modeling decisions and provided input data, including groundwater pumping records, surface water delivery records, urban demand, and local water levels and quality data.

Local agencies with consistent representation in meetings related to the development of the ESJWRM included San Joaquin County, WID, City of Lodi, NSJWCD, LCSD, CCWD, City of Stockton, Cal Water, SEWD, City of Lathrop, City of Manteca, SSJID, City of Escalon, OID, and Stanislaus County. Other agencies contributed local data to information collection efforts later in the GSP development and revision process.

Online System for Well Completion Reports – The OSWCR is a DWR program used to document and compile boring or well completion records throughout California. There are as many as 2 million domestic, irrigation, and monitoring water wells in California included in this dataset, including approximately 10,000 domestic wells located in the Eastern San Joaquin Subbasin. When a well is constructed, modified, or destroyed, drilling contractors are required to submit a Well Completion Report to DWR for upload to the interactive OSWCR web site. OSWCR is used as a data source for wells identified for monitoring. In this GSP, the OSWCR database was used to describe the Plan area and identify sustainable management criteria.

1.2.2.2 Groundwater Quality Monitoring and Data Sources

1.2.2.2.1 Groundwater Ambient Monitoring and Assessment Program The GAMA Program is an extensive groundwater quality monitoring program that was established by the SWRCB in 2000. The program compiles groundwater quality data from several agencies including the DWR, USGS, Department of Pesticide Regulations (DPR), Lawrence Livermore National Laboratory (LLNL), and others. Agencies submit data from monitoring wells for 258 constituents including total dissolved solids (TDS), nitrates and nitrites, arsenic, and manganese. GAMA data for the Eastern San Joaquin Subbasin contains water quality results collected by the SWRCBDDW (formerly DHS-DDW), DPR, DWR, LLNL, and USGS from the 1940s to present. Figure 2-3 in Chapter 2: Basin Setting shows the GAMA well locations throughout the Eastern San Joaquin Subbasin, roughly 6,800 monitoring points.

1.2.2.2.2 Water Data Library
DWR’s WDL contains groundwater quality data in addition to the groundwater level records described previously. This information includes data from discrete groundwater quality samples collected by DWR and other cooperating entities.

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Agency Information, Plan Area, and Communication November 2024 These water quality data list the entity responsible for taking the sample but do not specify what program the sample was taken under. The WDL water quality measurements are available through the CNRA Open Data website as a bulk download, or through the WDL website on a per-station basis. WDL water quality measurements in this GSP are utilized for basin characterization but are acquired from the other programs.

1.2.2.2.3 National Water Information System
The USGS NWIS contains groundwater quality data, in addition to the groundwater level measurements previously discussed. Groundwater quality results in NWIS relate to GAMA records, but there is no direct link between the two databases. Some NWIS sites have a State ID listed, which is a common identifier used for wells. This indicates these wells can be connected to other databases using the State ID information. However, differences in the format of the State ID between NWIS and other databases create challenges in cross referencing between databases. In this GSP, NWIS water quality measurements are utilized for basin characterization but are acquired from the other programs.

1.2.2.2.4 Division of Drinking Water
The SWRCB DDW monitors public water system wells for Title 22 requirements such as organic and inorganic compounds, metals, microbial, and radiological analytes. Data are available for active and inactive drinking water sources for water systems that serve the public – defined as wells serving 15 or more connections or more than 25 people per day. Data are electronically transferred from certified laboratories to DDW daily. Data generated from this program are used for regulatory compliance by water purveyors and become part of Consumer Confidence Reports (CCR) and GAMA.

1.2.2.2.5 GeoTracker
GeoTracker, operated by the SWRCB, contains records for sites that require cleanup, such as leaking underground storage tank sites, Department of Defense sites, and cleanup program sites. GeoTracker also contains records for various unregulated projects as well as permitted facilities including: ILRP, future CV-SALTS, oil and gas production, operating permitted underground storage tanks, and land disposal sites. GeoTracker receives records and data from SWRCB programs and other monitoring agencies.

1.2.2.2.6 Irrigated Lands Regulatory Program
The Irrigated Lands Regulatory Program (ILRP) is a program established by the CVRWQCB focused on monitoring and regulating the concentration of pesticides, toxicity, and nutrients (such as TDS and nitrates) in surface and groundwater. General orders under the ILRP require agricultural users in the Central Valley to prevent sediment, fertilizer, pesticides, manure, and other materials used in farming from leaving the field in irrigation or stormwater and entering surface waters or leaching below the root zone to groundwater. Agricultural users biannually sample and submit data for irrigation and domestic wells. As part of the ILRP, the San Joaquin County & Delta Water Quality Coalition members monitor drinking water wells on enrolled parcels for nitrates. This requirement began January 1, 2019, based on the February 7, 2018 revision of ILRP WDR (Order) for the Eastern San Joaquin River Watershed by the SWRCB. The ILRP program is in the process of developing a comprehensive monitoring network for future use to address the ILRP data objectives. The San Joaquin County & Delta Water Quality Coalition members also monitor domestic wells for nitrate in high vulnerability areas.

1.2.2.2.7 Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS) The Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS) program was launched by the CVRWQCB in 2006 in an effort to develop sustainable salinity and nitrate management plans and solutions to the salinity problem in the Central Valley. CV-SALTS is a coalition of agricultural, business, and industry parties along with local, regional, and state governments which facilitate and fund efficient management systems of salinity, technical studies, and the 2017 Final Salt and Nitrate Management Plan (SNMP). The 2017 SNMP was developed based on a EXHIBIT 1
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Agency Information, Plan Area, and Communication November 2024 detailed water quality analysis conducted for salinity (represented by TDS) and nitrates using measurements from wells across multiple agencies from 2000-2016. Appendices to the SNMP and supporting documents contain summary information about these constituents by Subbasin, including Eastern San Joaquin. Basin Plan Amendments identify specific actions and recommendations for individual basins in the Central Valley. Efforts are underway to implement a salinity monitoring program and the CV-SALTS program will likely require monitoring and data submittal.

1.2.2.3 Interconnection of Databases
Several of the databases discussed above utilize the same water level or water quality data. These records often specify the monitoring entity responsible for the measurement. Although these data overlap between databases, the correlation between databases is not specified. For example, water level data in the WDL are also in CASGEM, but this link is not mentioned in WDL records. This lack of connection poses problems for gathering water level and quality data in the Eastern San Joaquin Subbasin and throughout California. For instance, if certain water level data are gathered through CASGEM but not uploaded to NWIS, users who gather water level measurements through NWIS would miss the CASGEM data. Efforts have been made in the development of this Plan to overcome the issue related to overlap and poor correlation between databases, but the issue remains. It is recommended that agencies work together to utilize a common unique identifier to ease use of multiple datasets.

1.2.2.4 Land Subsidence Monitoring
Subsidence monitoring is performed using continuous global positioning system (CGPS) stations, extensometers, and Interferometric Synthetic Aperture Radar (InSAR) surveys. CGPS data are primarily available from two programs.

UNAVCO’s Plate Boundary Observatory Program – Reporting since 2004, the UNAVCO (formerly University Navigation Satellite Timing and Ranging or NAVSTAR Consortium) Plate Boundary Observatory network consists of a network of about 1,100 continuous global positioning system (CGPS) and meteorology stations in the western United States to measure deformation resulting from the constant motion of the Pacific and North American tectonic plates in the western United States. Stations located within the Subbasin contain data from at least 2006 to current and include station P309 located east of Linden and station P273 located west of Lodi. Other stations are also available in nearby Subbasins.

University of Nevada Geodetic Laboratory (UNGL) - Several additional CGPS stations from the University of Nevada Geodetic Laboratory (UNGL) were also located in the Subbasin. These stations provide additional subsidence data for the Subbasin; however, these stations have drawbacks, such as data gaps, and discontinuous monitoring, and are used on an academic/research basis that may result in increased monitoring gaps. Station CA15 is located north of the city of Stockton and has a continuous period of record between September 2013 and October 2021. Station CMNC is located along the southern edge of the Camanche Reservoir and has observations in 2020 and between February 2022 through January 2024. These locations also provided additional spatial coverage to the UNAVCO and SOPAC CGPS stations
Subsidence analyses have also been conducted using satellite-based methods over limited time periods, as described below.

United States Geological Survey – The USGS report Land Subsidence along the Delta-Mendota Canal in the Northern Part of the San Joaquin Valley, California, 2003-10 (Sneed et al., 2013) presents land subsidence data in the southwestern portion of the Eastern San Joaquin Subbasin from 2007 to 2010. Data for about 100 square miles of the Subbasin were recorded using Interferometric Synthetic Aperture Radar (InSAR) processing, a satellite-based remote sensing technique that can detect ground-surface deformation. Two InSAR techniques were used: conventional InSAR and persistent scatter (PS) InSAR. Both sources of data were collected from the Japanese Aerospace Exploration Agency’s Advanced Land Observing Satellite.

California Department of Water Resources -– DWR has made two InSAR datasets available for SGMA application:

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There are no DWR or USGS extensometers in the Eastern San Joaquin Subbasin.

1.2.2.5 Groundwater Storage Monitoring
There are no existing programs that conduct regular monitoring specific to groundwater storage in the Eastern San Joaquin Subbasin. The ESJWRM historical model was used to generate estimates for historical groundwater storage based on a series of inputs including historical groundwater elevation data. The ESJWRM generated estimates for current and projected volumes of groundwater in storage based on assumptions for how future conditions may change relative to historical conditions.

1.2.2.6 Interconnected Surface Water Monitoring
There are no existing programs that conduct regular monitoring specific to the interconnection of surface water to groundwater in the Eastern San Joaquin Subbasin. However, surface water monitoring and groundwater level monitoring will be integrated to characterize spatial and temporal exchanges between surface water and groundwater and to estimate potential depletions of surface water caused by groundwater extractions. Additional information on how the depletions monitoring network was developed, monitoring frequency, and summary protocols is provided in Chapter 4: Monitoring Networks. Sources of groundwater level data are described in Section 1.2.2.1. Surface water data on stream flows and levels from stream gages are available from the USGS, CDEC, and local agencies.

1.2.2.7 Other Water Management Programs and Plans
The subsections below contain descriptions of historical and current water management programs and plans, including Integrated Regional Water Management Plans (IRWMPs), Agricultural Water Management Plans (AWMPs), and Urban Water Management Plans (UWMPs) that apply to the Eastern San Joaquin Subbasin.

1.2.2.7.1 Groundwater Management Plan
The Eastern San Joaquin Groundwater Basin Groundwater Management Plan (GMP), developed by the Northeastern San Joaquin County Groundwater Banking Authority in September 2004, was a collaborative effort between local water interests with historically diverse viewpoints to reinforce local control and provide direction for the sustainable development of groundwater resources. The GMP covered a geographic region that included the entire Eastern San Joaquin Subbasin that falls within San Joaquin County but excluded portions within Calaveras and Stanislaus counties to the east. The GMP boundaries were generally defined by the San Joaquin County line to the east, the San Joaquin River to the west, Dry Creek to the north, and the Stanislaus River to the south. A map of the Eastern San Joaquin GMP Region is shown in Figure 1-15.

Now a legacy document superseded by the Eastern San Joaquin GSP, the 2004 GMP provided valuable resources related to potential concepts, projects, and monitoring strategies that were leveraged in the early versions of this GSP (Northeastern San Joaquin County Groundwater Banking Authority, 2004). The following management objectives influenced the development and implementation of the GSP:
• Maintain or enhance groundwater elevations to meet the long-term needs of groundwater users within the Groundwater Management Area
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Agency Information, Plan Area, and Communication November 2024 • Maintain or enhance groundwater quality underlying the Basin to meet the long-term needs of groundwater users within the Groundwater Management Area
• Minimize impacts to surface water quality and flow due to continued Basin overdraft and planned conjunctive use
• Prevent inelastic land subsidence due to continued groundwater overdraft Figure 1-15: Eastern San Joaquin GMP Region Setting

1.2.2.7.2 Integrated Regional Water Management Plan
The Eastern San Joaquin Integrated Regional Water Management Plan (Eastern San Joaquin IRWMP) is a collaborative regional planning document that was published in June 2014, with an Addendum released in February 2021. The IRWMP defines and integrates key water management strategies to establish protocols and courses of action to implement the Eastern San Joaquin Integrated Conjunctive Use Program (ICU Program). The ICU Program was designed to implement a comprehensive, prioritized set of projects and management actions to meet adopted EXHIBIT 1
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Agency Information, Plan Area, and Communication November 2024 Best Management Objectives, moving the Eastern San Joaquin County Region toward the goal of sustainable and reliable water supplies (San Joaquin County, 2021).

The following IRWMP objectives related to groundwater use would potentially influence implementation of the GSP:
• Minimize adverse impacts to agriculture, communities, and the environment • Maximize efficiency and beneficial use of supplies
• Protect and enhance water rights and supplies

1.2.2.7.3 Mokelumne Interregional Sustainability Program Report The Mokelumne Watershed Interregional Sustainability Evaluation (MokeWISE) was formed following efforts made by the Mokelumne River Forum over seven years by a diverse set of stakeholders in the Upper and Lower Mokelumne River watersheds, with the objective to develop and evaluate alternatives to optimize water resources management within the Mokelumne-Amador-Calaveras (MAC) and Eastern San Joaquin IRWM planning regions. The plan offers a bi-regional approach by bringing together stakeholders, and it brings together the interregional sections of two IRWM regions identified as the Mokelumne River Forum (San Joaquin GBA, 2015).

The following MokeWISE objectives related to groundwater use would potentially influence implementation of the GSP:
• Groundwater is not considered a viable additional source in Amador and Calaveras counties • The Eastern San Joaquin Subbasin is considered critically overdrafted • Groundwater is not considered a viable additional supply source in Amador and Calaveras counties due to low yield, unreliability, age of groundwater, and limited storage options, although conjunctive use and recharge opportunities may be available

1.2.2.7.4 Agricultural Water Management Plans
AWMPs were developed and adopted by OID, SEWD, SSJID, and WID in 2015 in compliance with SB X7-7 of 2009, which requires certain agricultural water suppliers to prepare an AWMP and implement Efficient Water Management Practices (EWMPs). The Critical EWMPs include:
• Measure the volume of water delivered to customers with sufficient accuracy to comply with requirements of the Water Code
• Adopt a pricing structure based at least in part on quantity delivered (Volumetric Pricing) Applicable Conditional EWMPs that have the benefit of less applied water or increasing system efficiency include:
• Facilitate alternative land use for lands with exceptionally high water duties • Facilitate use of available recycled water
• Facilitate financing of capital improvements for on-farm irrigation systems • Implement an incentive pricing structure that promotes one or more of the goals identified in the Water Code • Expand line or distribution systems, construct regulating reservoirs to increase distribution system flexibility and capacity, decrease maintenance, and reduce seepage
• Increase flexibility in water ordering by, and delivery to, water customers within operational limits EXHIBIT 1
781
2024 Groundwater Sustainability Plan Amendment 1-33
Agency Information, Plan Area, and Communication November 2024 • Construct and operate supplier spill and tailwater recovery systems • Increase planned conjunctive use of surface water and groundwater • Automate canal control structures
• Facilitate or promote customer pump testing and evaluation • Designate a water conservation coordinator who will develop and implement the water management plan and prepare progress reports
• Provide for the availability of water management services to water users • Evaluate the policies of agencies that provide the supplier with water to identify the potential for institutional changes to allow more flexible water deliveries and storage • Evaluate and improve the efficiencies of the supplier’s pumps The updated 2020 AWMPs provide a framework of management practices to help meet water management goals that align with the goals of the Eastern San Joaquin GSP.

1.2.2.7.5 Urban Water Management Plans
UWMPs are developed by Cal Water, CCWD, City of Lodi, City of Manteca, City of Ripon, City of Stockton, SSJID, and SEWD every five years according to requirements of the Water Code.

Agencies acting as GSAs use the following actions to encourage conservation and efficient use of water:
• Water waste prohibition ordinances
• Metered distribution systems
• Tiered water rates and conservation pricing
• Public education and outreach efforts
• Water conservation program coordination and staffing support • Free residential plumbing retrofit devices
• Washing machine rebate program

1.2.2.8 Canal Diversions and Seepage
Canal seepage in the Eastern San Joaquin Subbasin is tracked on a district-by-district basis. All of the major irrigation districts utilize a combination of natural watercourses, canals, and pipelines to distribute surface water diversions to their customers.

OID diverts water from the Stanislaus River at Goodwin Reservoir through the Joint Main Canal on the north side and the South Main Canal on the south side. Approximately 330 miles of laterals carry water to landowners off of the main canals. While the entire lateral system historically consisted of open, unlined ditches, 100 miles of the laterals have been converted to pipelines; 105 miles are open, concrete-lined ditches; and the rest remain unlined. Approximately 40 percent of the OID service area is within the Eastern San Joaquin Subbasin.

EXHIBIT 1
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2024 Groundwater Sustainability Plan Amendment 1-34
Agency Information, Plan Area, and Communication November 2024 In SSJID, similarly, the primary source of recharge in the groundwater system is conveyance seepage and deep percolation of applied water. SSJID diverts from the Stanislaus River initially and then sends the water through a system of lateral canals to its customers. Like OID, the entire system was open and unlined, but over time it has been slowly concrete lined and replaced with buried pipelines.

SEWD uses two unlined canal systems to deliver water from the Stanislaus River: Upper Farmington Canal and Lower Farmington Canal. SEWD also uses natural watercourses to distribute their water, such as rivers, creeks, and sloughs.

CSJWCD also uses the Upper Farmington Canal for distribution, as well as natural watercourses within its boundaries.

Historically, WID has also made efforts to improve the efficiency of the delivery infrastructure it maintains. Water for WID is diverted from the Mokelumne River and from the Delta at the end of Beaver Slough. In 2015, WID had about 100 miles of lined and unlined canals, and pipelines.

Canal seepage, generally considered a loss to districts in the short term, provides groundwater recharge and has played and will continue to play a crucial role in the long-term sustainability of groundwater resources in the Eastern San Joaquin Subbasin.

1.2.2.9 Conjunctive Use Programs Prior to SGMA Implementation Conjunctive use is the use of surface water to allow the Subbasin to recharge and store additional water supply, either through in-lieu use or direct recharge. This section describes conjunctive use programs that were in place in the Eastern San Joaquin Subbasin prior to the beginning of SGMA implementation in 2020, including both in-lieu recharge and direct recharge projects.

In-lieu recharge occurs for both agricultural and municipal purposes wherever surface water is being delivered to offset the use of groundwater. Agencies that conducted in-lieu recharge prior to SGMA implementation include CCWD, City of Lodi, City of Manteca, City of Stockton, CSJWCD, OID, SEWD, SSJID, and WID. Riparian users of surface water also benefit from in-lieu recharge.

Direct recharge projects existed in NSJWCD and SEWD, as shown below in Figure 1-16. NSJWCD’s Tracy Lake Groundwater Recharge Project includes direct recharge of 500 to 1,000 AF/year by placing surface water in the bed of South Tracy Lake to allow for percolation. The Cal-Fed/Costa Recharge project includes direct recharge of about 300 AF/year by flooding about 20 acres of vineyards post-harvest. NSJWCD is expanding these programs to add additional in-lieu and direct recharge projects in its service area. SEWD’s Farmington Groundwater Recharge Program was developed in 2001 with a conceptual plan to recharge surface water via field flooding on about 1,200 acres. SEWD has operated a 60-acre recharge site since 2003 as a result of the Farmington Program with additional 73 acres added in 2020. The observed recharge amount ranges from 2,800 AF/year to 5,800 AF/year with an average of 4,400 AF/year for a total recharge volume of about 65,000 AF since the inception of the project. SEWD also has several wells to pump some of this recharged water for municipal supply during especially dry years.

EXHIBIT 1
783
2024 Groundwater Sustainability Plan Amendment 1-35
Agency Information, Plan Area, and Communication November 2024 Figure 1-16: Locations of Groundwater Recharge Projects Prior to SGMA Implementation

1.2.3 Land Use Elements or Topic Categories of Applicable General Plans

1.2.3.1 General Plans in the Plan Area
San Joaquin County has jurisdiction over land use planning for the majority of the surface area of the Subbasin.

Stanislaus County, Calaveras County, and the incorporated cities of Stockton, Manteca, Lodi, Ripon, and Escalon make up the remaining area. Implementation of the Eastern San Joaquin GSP may be affected by the policies and regulations outlined in the San Joaquin County General Plan, as well as the General Plans for the five cities, given that the long-term land use planning decisions that would affect the Subbasin are under the jurisdiction of the counties and respective cities.

This section describes how implementation of the various General Plans may change water demands in the Subbasin, how the General Plans may influence the GSP’s ability to achieve sustainable groundwater use, and how the GSP may affect implementation of General Plan land use policies. Policies outlined in the General Plans that will potentially influence implementation of the GSP are discussed below and listed in Appendix 1-F.

EXHIBIT 1
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2024 Groundwater Sustainability Plan Amendment 1-36
Agency Information, Plan Area, and Communication November 2024

1.2.3.1.1 San Joaquin County General Plan
The San Joaquin County General Plan describes the official county “blueprint” on the location of future land use, type of development encouraged, and decisions regarding resource conservation. Stakeholder input informed the development of the county’s vision and guiding principles, which represent the county’s core values and establish benchmarks for the General Plan’s goals and policies. The General Plan encourages preservation of the San Joaquin County’s groundwater resources and states that future urban and agricultural growth should occur within the sustainable capacity of these resources (SJC, 2016b).

1.2.3.1.2 Calaveras County General Plan
The Calaveras County General Plan has provided a framework for growth and development in Calaveras County. The Calaveras County General Plan, initially developed in 1996, underwent an extensive update process in collaboration with local stakeholders and policymakers to understand the challenges facing the community and to enact a common vision for the future. This update, with its various elements, was finalized in 2019. (The Housing Element was finalized in 2023.)
The Calaveras County General Plan recognizes that water is a limited and valuable resource and that the region is experiencing localized problems with both water supply and quality. To mitigate these issues, the General Plan delineates policies and goals that promote sustainable water resources management in the region (Calaveras County, 2019).

1.2.3.1.3 Stanislaus County General Plan
The Stanislaus County General Plan provides a comprehensive, long-term plan to guide development within the Stanislaus County boundaries through 2035. The General Plan was updated and adopted in 2016 to reflect the evolving conditions of the region. While Stanislaus County’s economic base remains predominantly agricultural, the county's land use and economy continue to diversify in response to increased pressure to convert productive agricultural lands to non-agricultural uses. To address the region’s changing water needs, the Stanislaus County General Plan supports goals, policies, and implementation measures that promote sustainable water management and protect the local groundwater sources (Stanislaus County, 2016).

1.2.3.1.4 City of Stockton General Plan
The City of Stockton General Plan establishes the City’s 2040 vision and provides supporting goals, policies, and actions needed to achieve it. The General Plan for the 2040 vision was built upon the prior 2035 Stockton General Plan (adopted in 2007) and was a collaborative process that involved a diverse group of stakeholders and interests. The General Plan update incorporated feedback from City Council study sessions, Planning Commission study sessions, community workshops, and numerous other public meetings and outreach events (City of Stockton, 2016).

The City of Stockton’s General Plan recognizes that groundwater supplies are vital to Stockton’s ability to meet current and future water demands. The city has focused attention on optimizing available surface water supplies and cooperating with agencies in the region to manage the groundwater resources at a sustainable yield and to address regulatory pressures, droughts, and saline intrusion (City of Stockton, 2016).

1.2.3.1.5 City of Lodi General Plan
The City of Lodi General Plan Update, published in 2010, outlines a vision for Lodi’s future and provides a set of policies and programs that guide community growth and development. The 2010 General Plan Update replaced the 1991 General Plan and was informed by input from community members and stakeholders who participated in the planning process through different avenues, including public workshops and meetings, mail surveys, interviews, presentations, and newsletters (City of Lodi, 2010).

EXHIBIT 1
785
2024 Groundwater Sustainability Plan Amendment 1-37
Agency Information, Plan Area, and Communication November 2024 The General Plan recognizes that groundwater contamination and overdraft in the Eastern San Joaquin Subbasin can threaten the city’s ability to meet current water demands and limit future development (City of Lodi, 2010).

1.2.3.1.6 City of Manteca General Plan
The City of Manteca adopted the current Manteca General Plan in February 2024 to reflect the current conditions of the city. This recent version updated the 2003 General Plan and was the result of a collaborative process between community members, city staff, and decision-makers to produce a General Plan that is current, progressive, flexible, and viable. The General Plan Update also reevaluates the existing vision for Manteca through 2040, incorporates new planning strategies, and brings the General Plan into compliance with recent social and environmental justice policies and laws (City of Manteca, 2024).

The Manteca General Plan Update recognizes that groundwater is a large source of potable water supply for the city and that the Eastern San Joaquin Subbasin is in overdraft. To address groundwater overdraft in the city, a significant number of policies in the General Plan promote increased understanding of the Eastern San Joaquin Subbasin.

1.2.3.1.7 City of Escalon General Plan
The Escalon General Plan was developed by the city in 1994 and updated in 2010 to reflect the most current conditions of the city and to provide comprehensive planning for future development. The Escalon General Plan was developed through a cooperative effort involving the City Council and Planning Commission, city staff and their consultants, and stakeholders (City of Escalon, 2010). The Escalon General Plan delineates policies that support the long-term preservation of water supplies and water quality in the Eastern San Joaquin Subbasin (City of Escalon, 2010).

1.2.3.1.8 City of Ripon General Plan
The City of Ripon’s General Plan was updated in 2006 to guide the use of private and public lands within the community’s boundaries through 2040. The General Plan update provides a framework for promoting growth and reevaluates where growth should be located. The General Plan development process was informed by community members representing a wide variety of interests, city department heads, and staff representatives of public agencies (City of Ripon, 2006).

The General Plan supports the preservation of groundwater quantity and quality as it is an important source of water supply for the City of Ripon. Future development within the planning area is expected to have minimal effects on groundwater supplies, although it is unknown how development will impact groundwater quality. The General Plan predicts that the City of Ripon may have to abandon a large number of wells as sources of potable water due to localized contamination, and, as a result, additional development may be prohibited until an adequate source of potable water can be identified. Surface water is expected to meet water demands for surrounding agricultural uses (City of Ripon, 2006).

1.2.3.2 Effect of GSP Implementation on Applicable General Plans The General Plans in the Subbasin provide guidelines to facilitate anticipated growth within the sustainable capacity of existing resources. Successful land use planning also promotes sustainable water supply and use within the region.

Due to the complementary nature of the General Plans and the GSP, the goals and policies in the General Plans support the ability of the GSAs to achieve sustainability.

Implementation of the GSP, including changes in groundwater management, may influence the type of land use and location of future development, depending on the level of changes set forth by the GSP, such as enacted programs, plans, and policies. While General Plan implementation may result in land use changes and changes in water consumption, minimal change in water demand is expected from GSP implementation. The potential for future management actions, which could impact water supplies and development, is discussed in Section 6.5. Most of the land within the Eastern San Joaquin Subbasin is currently developed to some use, and conversion from agricultural EXHIBIT 1
786
2024 Groundwater Sustainability Plan Amendment 1-38
Agency Information, Plan Area, and Communication November 2024 uses to urban uses is not anticipated to increase water demand. However, conversion from agriculture to urban use may have an effect on water source, depending on the location in the Subbasin, and may shift supply from groundwater to surface water.

1.2.3.3 Land Use Plans Outside the Plan Area
Land use decisions in neighboring areas experiencing overdraft are likely to affect groundwater conditions in the Eastern San Joaquin Subbasin. Ongoing coordination with neighboring groundwater subbasins will include updates on major land use planning that may impact the groundwater system. The cities of Tracy, Lathrop, Modesto, Galt, and Elk Grove are the largest urban areas neighboring the Eastern San Joaquin Subbasin. The portions of the Tracy and the Delta-Mendota Subbasins that are adjacent to the Eastern San Joaquin Subbasin are also located within San Joaquin County. These land use planning areas are covered by the San Joaquin County General Plan described in Section

1.2.3.1.1. The City of Tracy, located within San Joaquin County and the Tracy Subbasin, updated its General Plan in 2011. The City of Tracy General Plan identifies the Tracy Subbasin as a source of water supply for the city. The City of Tracy is working towards reducing its reliance on groundwater and reserving its use for emergency situations and droughts (City of Tracy, 2011).

The City of Lathrop, located within San Joaquin County and the Tracy Subbasin, relies on potable water supplies consisting of a combination of groundwater and treated surface water from the South County Water Supply Program.

The General Plan for the City of Lathrop was first adopted in 1991 and last amended in 2022. The General Plan reflects the city’s long-range aspirations by defining goals and policies for current and future development and by providing guidance on proposed projects.

The City of Modesto, located in Stanislaus County, relies on the Modesto and Turlock Subbasins for its groundwater supplies. The City of Modesto General Plan, last updated in March 2019, identifies historical declining groundwater levels as a result of increased urban demands. While steps have been taken to address groundwater levels, the General Plan calls for continued protection and conservation of groundwater sources while pursuing additional water supplies to meet continued growth (City of Modesto, 2019).

The City of Galt, located in Sacramento County, is on the southern edge of the Cosumnes Subbasin and last updated its General Plan in 2009. Groundwater from the Cosumnes Subbasin is the sole source of water supply for the city.

The General Plan outlines policies to ensure groundwater availability and protection (City of Galt, 2009).

The City of Elk Grove, located in Sacramento County, relies heavily on groundwater from the South American Subbasin. To address years of drought conditions and low precipitation, the City of Elk Grove Draft General Plan outlines several goals and policies to protect groundwater supplies while meeting increased water demands from agricultural production and a growing population (City of Elk Grove, 2018).

1.2.3.4 Well Permitting
On 28 March 2022, Governor Newsom signed Executive Order (EO) N-7-22 to amend prior proclamations of states of emergency due to California’s ongoing drought conditions. EO N-7-22 required that additional steps be taken by well permitting agencies to approve a permit for the construction of a new well or alternation of an existing well located in a medium- or high- priority basin subject to SGMA. For applicable wells, permitting agencies must obtain written verification from the GSA managing the area of the basin where the proposed well is to be located that the well would not conflict with the GSP or decrease the likelihood of the basin reaching its Sustainability Goal. EO N-7-22 was subsequently rescinded once the drought-related state of emergency was lifted.

On 13 February 2023, Governor Newsom signed EO N-3-23 to keep in place some of the provisions originally contained EO N-7-22 One of the provisions retained by EO N-3-23 is the requirement that well permitting agencies not approve a permit for a new well or alteration of an existing well without first obtaining written verification of GSA approval that EXHIBIT 1
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2024 Groundwater Sustainability Plan Amendment 1-39
Agency Information, Plan Area, and Communication November 2024 groundwater extraction by the proposed well would not be inconsistent with the GSP and the programs it contains. The EO exempts de minimis new wells and new wells that replace existing, actively permitted wells with wells that will produce an equivalent quantity of water when the existing well is being replaced because it has been acquired by eminent domain or while under threat of condemnation.

The Basin GSAs are working with the permitting agencies (i.e., counties) to review and provide written verifications for permit applications within their jurisdictions as required under the EO. As described above, several counties have already amended their well permitting processes to incorporate GSA verification.

1.2.3.4.1 San Joaquin County
San Joaquin County oversees a well permitting program for any new, replacement, back-up, and de minimis well construction. The purpose of this program is to prevent groundwater contamination and safety hazards by regulation of the location, construction, repair, and destruction of water supply, monitoring, and geophysical wells and borings.

Pursuant to Water Code §13808, all new wells that do not meet the exemption criteria must submit additional information prior to the issuance of a permit by the Environmental Health Department. The permit program is enforced by Ordinance Code of San Joaquin County §9-1115, and Municipal Codes of Stockton, Lodi, Manteca, Tracy, Escalon, and Ripon. Applicants must provide information about groundwater elevation estimates, land elevation estimates, extraction volume estimates, depth of Corcoran Clay, and other basic well characteristics.

San Joaquin County has established water well standards for new wells that define property line setbacks (at least 10 feet depending on well type), casing perforations, gravel packing, well seals, backflow prevention, disinfection requirements, sampling taps, and more, as well as the requirement for installing monitoring device(s) for groundwater extraction, elevation, and/or water quality. Other setbacks for potential sources of contamination or pollution require at least 50 feet depending on the contamination source and well type.

The San Joaquin County Well Standards outline well grouting and construction standards to prevent contamination, pollution, and degradation of water wells and of the groundwater by intrusion of poor-quality water. Wells must have a watertight annular seal near the land surface to keep surface water and other potential contamination out of the well.

The minimum depth of the annular seal depth for wells in San Joaquin County is summarized in Table 1-1 (SJC EHD, 1993).

Table 1-1: Minimum Depth of Seal Below Ground Surface
for Wells in San Joaquin County
Well Type Feet
Public Water Supplies 100
Individual Domestic Well 100
Industrial Wells 100
Agricultural Wells 50
In response to EO N-3-23, San Joaquin County updated its well permitting process to require applicants to fill out either a Well Exemption Statement (for exempt wells) or a New Well Information Form (for non-exempt wells). For non-exempt wells, the New Well Information Form is forwarded with the rest of the application to the applicable GSA for review and consideration for a written verification.

1.2.3.4.2 Calaveras County
The Calaveras County Board of Supervisors adopted a well construction and destruction ordinance in 1998. The ordinance mandates that a permit must be obtained from the Calaveras County Environmental Health Department prior to development or modification of any well within the Calaveras County boundaries. The purpose of the program is to regulate the construction, alteration, abandonment, and destruction of wells such that groundwater will not be EXHIBIT 1
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2024 Groundwater Sustainability Plan Amendment 1-40
Agency Information, Plan Area, and Communication November 2024 contaminated and that groundwater supplies will not jeopardize the health, safety, or welfare of Calaveras County residents.

To prevent polluted or contaminated water from entering the well, the well program established a minimum depth at which the annular space should be filled as well as minimum horizontal setback requirements. Horizontal setbacks from property lines range from 10 feet (for small parcels) to 150 feet (for underground storage with nearby wells at least 25 feet away). The minimum annular seal depths for wells in Calaveras County are summarized in Table 1-2 (Calaveras County Board of Supervisors, 2008).

Table 1-2: Minimum Depth of Seal Below Ground Surface for Wells in Calaveras County Well Type Feet
Public drinking water well 50
Commercial well 50
Industrial well 50
Individual domestic well 20
Agricultural well 20
Vertical geothermal exchange wells 20
Wells within 25 feet of a water way 20 feet below the bed of the water way In response to EO N-3-23, Calaveras County updated its well permitting process to require applicants to fill out either a Well Exemption Statement (for exempt wells) or a New Well Information Form (for non-exempt wells). For nonexempt wells, the New Well Information Form is forwarded with the rest of the application to the applicable GSA for review and consideration for a written verification.

1.2.3.4.3 Stanislaus County
Pursuant to Chapter 9.36 of the Stanislaus County Code, well owners must first receive a valid permit from Stanislaus County to construct, install, repair, or destroy any well or well seal within the county. Stanislaus County DER is responsible for reviewing the applications and issuing permits. On April 5, 2022, the county adopted the “Stanislaus County Groundwater Well Siting and Construction Guidelines,” which prescribed well annular seal depths to be more protective than current standards, with special requirements to address local hydrogeologic conditions and know water quality issues. The default minimum seal depth was increased from 20-50 feet to 50-80 feet and deeper seals are specified that exceed the state well standards, (CA DWR, 1991), to provide additional protection under locally variable conditions. Standards for seal depths were identified for the safe construction of all wells to prevent the intermixing of water between the upper zone and underlying aquifers.

In 2014, the DER adopted a groundwater ordinance to prohibit unsustainable extraction of groundwater in unincorporated areas of the county. The DER reviews each well permit application and determines whether the well is subject to, or exempt from, the prohibitions in the Groundwater Ordinance. Permit applications for wells intended to extract 2 AF/year of groundwater or less are exempt from the prohibitions in the groundwater ordinance (Stanislaus County, 2019b). If the permit applicant is not exempt, a supplemental application for non-exempt wells must be submitted and demonstrate that the groundwater pumped from the well will be sustainably extracted and will not cause any of the “Undesirable Results” listed in Section 9.37.030 (9) of the ordinance. Additional permit application fees may be required, and the application review is conducted at the expense of the applicant (Stanislaus County, 2019c).

In response to EO N-3-23, Stanislaus County updated its well permitting process to refer applicable well permits to the GSAs for approval. If a GSA finds that a well permit application is not consistent with requirements in its GSP to prevent Undesirable Results, the applicant must provide substantial evidence that the proposed extraction is will not cause or contribute to their occurrence in accordance with Stanislaus County’s Discretionary Well Permitting Implementation Guidelines.

EXHIBIT 1
789
2024 Groundwater Sustainability Plan Amendment 1-41
Agency Information, Plan Area, and Communication November 2024 The minimum annular seal depths for wells in Stanislaus County are summarized in Table 1-3, and are consistent with the state well standards (CA DWR, 1991).

Table 1-3: Minimum Depth of Seal Below Ground Surface for Wells in Stanislaus County Special Management Area Feet
Corcoran clay area upper zone 50 – 80
Corcoran clay area lower zone at least 10 feet into Corcoran clay below the upper zone Alluvial fan upper zone 50 – 80
Alluvial fan lower zone 50 – 80 or at least 10 feet into a competent clay layer below the upper zone
Fractured bedrock 50 or into the first solid rock stratum below the water table or to prevent the vertical migration of pollution Wells completed in setback zones Qualified Professional required Wells completed in areas with
potential lower zone contamination
Qualified Professional required

1.2.3.4.4 Sacramento County
Sacramento County, which borders the northern boundary of the Eastern San Joaquin Subbasin (see Figure 1-6), oversees well permitting within their jurisdiction and requires property owners to obtain a permit for work including well construction, modification, repair, inactivation, destruction, installation, and replacement. Each well or pump requires its own permit application and fee, but waivers can be considered for multiple wells or exploratory borings of similar construction (Sacramento County, 2019).

The Sacramento County Code water well standards are designed to meet or exceed the water well standards in DWR’s Bulletin 74-81 and 74-90. These standards apply to all types of monitoring wells, vapor extraction wells where applicable, and any other well installed in an area where special precautions are necessary to protect groundwater quality. The Sacramento County Environmental Management Department has the power under special circumstances to grant a variance from provisions in Chapter 6.28 of the Sacramento County Code and to prescribe alternative requirements in their place (Sacramento County, 2019).

The minimum annular seal depth for wells in Sacramento County is 50 feet for all well types, except for in cases of special approval (Sacramento County, 2019).

1.2.4 Additional GSP Elements
The Additional GSP Elements section of the GSP provides GSAs with the opportunity to discuss “any additional Plan elements included in Water Code §10727.4 that the Agency determined to be appropriate”. These additional elements include:
• Control of saline water intrusion
• Wellhead protection areas and recharge areas
• Migration of contaminated groundwater
• A well abandonment and well destruction program
• Replenishment of groundwater extractions
• Activities implementing, opportunities for, and removing impediments to, conjunctive use or underground storage
EXHIBIT 1
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2024 Groundwater Sustainability Plan Amendment 1-42
Agency Information, Plan Area, and Communication November 2024 • Well construction policies
• Measures addressing groundwater contamination cleanup, groundwater recharge, in-lieu use, diversions to storage, conservation, water recycling, conveyance, and extraction projects • Efficient water management practices, as defined in Water Code §10902, for the delivery of water and water conservation methods to improve the efficiency of water use • Efforts to develop relationships with state and federal regulatory agencies • Processes to review land use plans and efforts to coordinate with land use planning agencies to assess activities that potentially create risks to groundwater quality or quantity • Impacts on groundwater dependent ecosystems
Each of the Additional Elements listed are relevant and important to the Eastern San Joaquin Subbasin, and are discussed throughout this GSP, as identified below.

Control of saline water intrusion – Section 2.2.3 describes the current status of saline water intrusion in the Subbasin.

Section 3.2.4 addresses seawater intrusion as a sustainability indicator. Actions to identify and monitor for saline water intrusion is described in Section 3.3.3.

Wellhead protection areas and recharge areas – Section 1.2.3.4 addresses wellhead protection programs in San Joaquin County, Calaveras County, and Stanislaus County.

Migration of contaminated groundwater – The migration of contaminated groundwater that may impair water supplies is addressed in Section 3.3.3.

A well abandonment and well destruction program – Requirements and procedures for well destruction and abandonment are discussed in Section 1.2.3.4.

Replenishment of groundwater extractions – Proposed projects and management actions that will facilitate replenishment of groundwater extraction are discussed in Chapter 6: Projects and Management Actions. Areas where potential groundwater replenishment could occur through direct recharge are described in Section 2.1.4.5.

Activities implementing, opportunities for, and removing impediments to, conjunctive use or underground storage – Existing conjunctive use projects are identified in Section 1.2.2.9. The proposed projects and management actions that will address implementing, opportunities for, and removing impediments to, conjunctive use or underground storage projects in the Subbasin are discussed in Chapter 6: Projects and Management Actions.

Well construction policies – Section 1.2.3.4 addresses well construction policies in San Joaquin County, Calaveras County, and Stanislaus County. Annular well seal depth requirements are tabulated in Tables 1-1, 1-2, and 1-3.

Measures addressing groundwater contamination cleanup, groundwater recharge, in-lieu use, diversions to storage, conservation, water recycling, conveyance, and extraction projects – Proposed projects and management actions that address groundwater recharge, in-lieu use, diversions to storage, conservation, and water recycling are discussed in Chapter 6: Projects and Management Actions.

Efficient water management practices, as defined in Section 10902, for the delivery of water and water conservation methods to improve the efficiency of water use – Ongoing efforts to implement efficient water management practices are described in Section 1.2.2.7. Conservation methods and efficiency of water use are also noted in many local or regional general plans, detailed in Section 1.2.3. Projects relevant to this topic are discussed in Chapter 6: Projects and Management Actions.

EXHIBIT 1
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2024 Groundwater Sustainability Plan Amendment 1-43
Agency Information, Plan Area, and Communication November 2024 Efforts to develop relationships with state and federal regulatory agencies – A strong relationship between the GSAs and existing regulatory agencies is valuable to the success of this GSP. Efforts to develop this relationship are described in Chapter 7: Plan Implementation.

Processes to review land use plans and efforts to coordinate with land use planning agencies to assess activities that potentially create risks to groundwater quality or quantity – Summaries of land use plans both inside the Subbasin and in nearby Subbasins can be found in Section 1.2.3. Efforts are being made at the local level to develop a formal opportunity for GSAs to provide input on the land use and water-related elements of future General Plans and California Environmental Quality Act (CEQA) documentation to promote consistency with the GSP.

Impacts on groundwater dependent ecosystems – Groundwater dependent ecosystems (GDEs) are defined in Section 2.2.7. The methodology for identifying GDEs can be found in Section 2.2.7.1. A map of identified GDEs in the Subbasin is shown in Section 2.2.7.2. Adverse impacts to GDEs are described under Depletions of Interconnected Surface Water, Section 3.3.6, as part of the undesirable results discussion.

1.3 NOTICE AND COMMUNICATION

1.3.1 Beneficial Uses and Users in the Basin
The CVRWQCB designates all groundwaters in the Sacramento River Basin and San Joaquin River Basin as suitable or potentially suitable, at a minimum, for municipal and domestic water supply, agricultural supply, industrial service supply, and industrial process supply (CVRWQCB, 2016).

As listed in Water Code §10723.2, beneficial uses and users of groundwater in the region include the following interests:
• Agricultural users and domestic well owners that hold overlying groundwater rights. • Public water systems/municipal well operators in the Subbasin. • Community water systems (wells serving 15 or more connections or more than 25 people per day). 433 community water systems were identified in the Eastern San Joaquin Subbasin and are presented in Appendix 1-E Of these 433 community water systems, 182 are located in DAC or SDAC areas, shown also in Appendix 1-E.
• Local agencies that have land use planning jurisdiction. These include counties of San Joaquin, Calaveras, and Stanislaus, and cities of Stockton, Lodi, Manteca, Escalon, and Ripon. • Environmental users of groundwater, including species and habitat reliant on instream flows, as well as wetlands and GDEs. Identified GDEs are mapped in Figure 2-69 in Section 2.2.7.2. Freshwater species in the Eastern San Joaquin Subbasin are listed in Appendix 1-G. • Irrigation districts in the Subbasin that divert surface water to deliver to their customers. • Lands managed by the federal government. The San Joaquin River National Wildlife Refuge lies just outside of the Subbasin boundary. While managed by the State of California, Caswell Memorial SP is in the Subbasin and Carnegie SVRA and Franks Tract SRA are situated just outside of the Subbasin. • DACs and SDACs. DACs and SDACs are mapped in Figure 1-8 and are primarily in the western portions of the Subbasin. Approximately 27 percent of the Subbasin area is considered disadvantaged and 5.4 percent is considered severely disadvantaged. 33 percent of the Subbasin population is considered either DAC or SDAC; within that, 16.5 percent of the population is SDAC. DACs include the following census designated EXHIBIT 1
792
2024 Groundwater Sustainability Plan Amendment 1-44
Agency Information, Plan Area, and Communication November 2024 places (CDPs)1: Stockton City CDP, Terminous CDP, Taft Mosswood CDP, and French Camp CDP. Severely disadvantaged communities include: Kennedy CDP, August CDP, Garden Acres CDP, and Thornton CDP. • Entities that monitor and report groundwater elevations. Monitoring in the Subbasin is extensive. A list of monitoring agencies can be found in Section 1.2.2.
• California Native American tribes

1.3.2 List of Public Meetings Where the 2024 GSP was Discussed During the 2024 update of the ESJ GSP, meetings of the ESJGWA Board and Steering Committee were open to the public with meeting information noticed, as appropriate, and posted to the ESJGWA website (discussed below in Section 1.3.4.2.2). In addition, public meetings and an informational open house event were held throughout the GSP update process (see Section1.3.4.2.4).

Below is a list of the public meetings where elements of this 2024 GSP Amendment were discussed.

Meeting Type Date
Steering Committee Meeting November 8, 2023
Steering Committee Meeting December 13, 2023
ESJGWA Board Meeting January 10, 2024
Steering Committee Meeting March 13, 2024
ESJGWA Board Meeting March 13, 2024
Steering Committee Meeting April 10, 2024
ESJGWA Board Meeting June 12, 2024
Stakeholder Advisory Workgroup
Meeting #1
June 27, 2024
Stakeholder Advisory Workgroup
Meeting #2
July 17, 2024
Steering Committee Meeting August 14, 2024
ESJGWA Board Meeting August 14, 2024
1 A census designated place is a concentration of population identified by the United States Census Bureau for statistical purposes. CDPs are delineated for each decennial census as the statistical counterparts of incorporated places, such as cities, towns, and villages.

EXHIBIT 1
793
2024 Groundwater Sustainability Plan Amendment 1-45
Agency Information, Plan Area, and Communication November 2024 Meeting Type Date
Steering Committee Meeting September 11, 2024
GSA Open House September 25, 2024
ESJGWA Board Meeting December 11, 2024

1.3.3 Decision-Making Process
The ESJGWA Board is tasked with the vote and approval of policy decisions for the development and implementation of this GSP. The ESJGWA Board receives input from the Steering Committee, the PMC, and the public, as described in Section 1.1.4.2.

The governing bodies of each of the individual GSAs take action and provide direction to their Board member representatives and must individually adopt the final GSP Amendment. Projects will be administered by the GSA project proponents. Although the ESJGWA does not provide direct authority to require GSAs to implement projects, the ESJGWA will be working on GSA-level water budgets and evaluating the best ways to evaluate progress. Work toward implementing projects and management actions is further described in Sections 6.2 and 6.3, respectively. If the implementation of projects is not sufficient to achieve sustainability goals, a demand management policy, included as a management action in the 2024 GSP Amendment, provides a framework for how the GSAs of the Subbasin plan to achieve sustainability through other means. A description of the agencies that comprise the GSAs can be found in Section 1.1.4.3.

1.3.4 Opportunities for Public Engagement and How Public Input was Used Throughout the process of the initial development of the GSP and this particular update, the ESJGWA engaged both stakeholders and the public. This effort has been greatly aided by the facilitation support provided through DWR’s Facilitation Support Services Program. In some cases, outreach and engagement opportunities were specific to the initial development of the 2020 GSP; these are detailed in Section 1.3.4.1. In other cases, outreach and engagement opportunities began during the 2020 GSP development process and have been adapted or modified for this 2024 GSP Amendment; these are discussed in Section 1.3.4.2.

1.3.4.1 Opportunities Specific to the 2020 GSP Development Process

1.3.4.1.1 Groundwater Sustainability Workgroup
When developing the initial 2020 GSP, the ESJGWA convened a Workgroup in order to promote stakeholder input and relied upon the Workgroup when developing the 2020 GSP. The Workgroup began with an application process to ensure a diverse cross section of populations were represented to serve on the Workgroup. Workgroup members participated and provided valuable input throughout the 2020 GSP development process.

Applications were distributed to organizations within every GSA to establish a Workgroup that represented the region’s broad interests, perspectives, and geography. The Workgroup included members from a variety of organizations who represent one or more of the interested parties’ groups. Table 1-4 lists the organizations and interests represented on the Workgroup. While this Workgroup was not active during the 2024 GSP amendment process, the information collected during their involvement remains relevant and a guiding factor in this update and GSP implementation activities.

EXHIBIT 1
794
2024 Groundwater Sustainability Plan Amendment 1-46
Agency Information, Plan Area, and Communication November 2024 Table 1-4: Groundwater Sustainability Workgroup Interests (Collected During Development of 2020 GSP) Eastern San Joaquin Groundwater Authority Groundwater
Sustainability Workgroup – Interests Represented
AG Agricultural Community BUS Business
CM Neighborhood DAC Disadvantaged Communities
ENV Environmental INST Institutional
FM Flood Management NA Native American
GU Groundwater User
Role/Organization AG BUS CM DAC ENV FM GU INST NA Application Notes 2Q Farming ✓ ✓ ✓
2Q Farming is interested in making a
difference for agriculture and communities,
and in preserving water rights for future
generations so they will have the ability to
irrigate and access the water necessary for
life.

Agricultural Business – Farmer
Representative
✓ ✓ ✓ ✓ ✓ ✓ ✓
As a representative of agricultural business,
this member sees SGMA as an opportunity to
manage the Subbasin while keeping
jurisdiction, implementation, monitoring, and
oversight at the local level.

Calaveras County Resource
Conservation District ✓ ✓ ✓ ✓ ✓ ✓ ✓
Calaveras County RCD hopes to partner with
groundwater users in the western part of
Calaveras County to address sustainability
and recharge.

California Sportfishing Protection Alliance ✓ ✓ ✓ ✓ ✓
California Sportfishing Protection Alliance,
longtime Mokelumne River stakeholder, is
interested in reducing groundwater overdraft,
managing surface water responsibly, and
resolving longstanding conflicts.

Representative is interested in the technical
aspects of groundwater management and
gaining a better understanding of recharge.

EXHIBIT 1
795
2024 Groundwater Sustainability Plan Amendment 1-47
Agency Information, Plan Area, and Communication November 2024 Eastern San Joaquin Groundwater Authority Groundwater
Sustainability Workgroup – Interests Represented
AG Agricultural Community BUS Business
CM Neighborhood DAC Disadvantaged Communities
ENV Environmental INST Institutional
FM Flood Management NA Native American
GU Groundwater User
Role/Organization AG BUS CM DAC ENV FM GU INST NA Application Notes Catholic Charities of the Diocese of
Stockton
✓ ✓ ✓ ✓ ✓
The Environmental Justice Program of the
Catholic Charities of the Diocese of Stockton
works with disadvantaged communities.

Some of these communities have concerns
regarding drinking water quality and toxic
contamination of groundwater supplies.

Environmental Justice Coalition for Water ✓ ✓ ✓ ✓
The Environmental Justice Coalition for Water
is interested in ensuring that environmental
justice interests are present, informed, and
meaningfully engaged in a process that bears
considerable importance for health, wealth,
and growth.

J.R. Simplot Co. ✓ ✓ ✓
As a local industry representative with a stake
in groundwater quality, this representative
sees benefit in being part of the stakeholder
process.

Lima Ranch ✓ ✓ ✓ ✓ ✓
Lima Ranch views water as a precious
commodity that must be conserved and used
sustainably. Representative values preserving
water rights and using water efficiently.

Machado Family Farms ✓ ✓ ✓
Representative manages a family farm and
brings agricultural experience and experience
with the California Public Utilities Commission
to provide a balanced perspective.

EXHIBIT 1
796
2024 Groundwater Sustainability Plan Amendment 1-48
Agency Information, Plan Area, and Communication November 2024 Eastern San Joaquin Groundwater Authority Groundwater
Sustainability Workgroup – Interests Represented
AG Agricultural Community BUS Business
CM Neighborhood DAC Disadvantaged Communities
ENV Environmental INST Institutional
FM Flood Management NA Native American
GU Groundwater User
Role/Organization AG BUS CM DAC ENV FM GU INST NA Application Notes Manufacturers Council of the Central Valley ✓ ✓ ✓ ✓ ✓
Through their involvement as a stakeholder,
Manufacturer's Council of the Central Valley
provides resources to manufacturers
impacted by the implementation of GSPs and
to GSAs looking to work with the sector.

Restore the Delta ✓ ✓ ✓ ✓ ✓
Representative is interested in the link
between surface water flows for the
Sacramento-San Joaquin Delta and
groundwater management. Additionally, this
member brings connections for broad
environmental justice outreach.

San Joaquin Audubon ✓
San Joaquin Audubon is interested in overall
water use and environmental issues.

San Joaquin County Environmental Health
Department
✓ ✓ ✓
The San Joaquin County Environmental
Health Department plays a role in protecting
the area's groundwater resource, drinking
water, and public health.

San Joaquin Farm Bureau ✓ ✓ ✓ ✓ ✓
The San Joaquin Farm Bureau is interested in
helping manage and utilize the groundwater
reservoir to better supply all needs for the
short and long term.

Sequoia ForestKeeper ✓
Sequoia ForestKeeper has been submitting
comments on water-related issues to the
SWRCB since 2015.

EXHIBIT 1
797
2024 Groundwater Sustainability Plan Amendment 1-49
Agency Information, Plan Area, and Communication November 2024 Eastern San Joaquin Groundwater Authority Groundwater
Sustainability Workgroup – Interests Represented
AG Agricultural Community BUS Business
CM Neighborhood DAC Disadvantaged Communities
ENV Environmental INST Institutional
FM Flood Management NA Native American
GU Groundwater User
Role/Organization AG BUS CM DAC ENV FM GU INST NA Application Notes Sierra Club - Delta-Sierra Group ✓ ✓ ✓ ✓ ✓ ✓
Sierra Club cares about the future of the
Eastern San Joaquin Subbasin and
sustainability. They believe that
representation of individuals is lacking and
there is insufficient outreach.

Spring Creek Golf & Country Club ✓ ✓ ✓ ✓ ✓
Representative is golf course superintendent
at Spring Creek Golf & Country Club and is
interested in groundwater rights and
contributing to the stakeholder Workgroup.

The Hartmann Law Firm ✓ ✓ ✓ ✓ ✓
Representative is Advisory Water
Commissioner, District Counsel for multiple
reclamation districts.

The Wine Group ✓ ✓ ✓ ✓
The Wine Group has technical knowledge
and provides a unique viewpoint that supports
the successful development of a GSP for the
Eastern San Joaquin Subbasin.

Trinchero Family Estates and Sutter Home
Winery
✓ ✓ ✓ ✓ ✓
Trinchero Family Estates and Sutter Home
Winery is interested in helping develop a
balanced approach for communities and
businesses.

University of the Pacific ✓ ✓ ✓
Representative is an Emeritus Professor of
Operations/Engineering Management at the
University of the Pacific and is engaged in
research on stream flow diversion for
groundwater recharge.

EXHIBIT 1
798
2024 Groundwater Sustainability Plan Amendment 1-50
Agency Information, Plan Area, and Communication November 2024

1.3.4.1.2 Situation Assessment
During development of the initial 2020 GSP, the ESJGWA applied for and received facilitation support through DWR’s Facilitation Support Services Program to conduct a Situation Assessment, the purpose of which was to facilitate the stakeholder engagement process by determining stakeholder concerns related to the GSP development process. The facilitation services supported third-party interviews conducted with the members of the Workgroup in the winter of 2018 as part of the Situation Assessment. All Workgroup members were invited to participate in the Situation Assessment, and 17 were interviewed during a series of in-person and phone interview sessions. Assessment summary and highlights are available on the ESJGWA website.

Situation Assessment questions covered topics including:
• Outreach and engagement approach
• Meeting presentations
• Meeting discussions
• Strengthening the Workgroup process
• Decision making and input
• GSP development and plan content
• Resource and management conditions data
• Implementation considerations
Based on Situation Assessment findings, changes were made to the 2020 GSP development process, including meeting presentations and discussions, the draft GSP, and its review schedule.

1.3.4.2 Continuing Opportunities for Public Engagement
The sections below detail the opportunities for public engagement that were specific to this 2024 GSP Amendment.

Many began with the development of the initial 2020 GSP and have been continued and modified as appropriate to fit the needs of this particular GSP Amendment process.

1.3.4.2.1 Communication and Engagement Plan
With the support of the Workgroup, the ESJGWA developed an initial Stakeholder Outreach and Engagement Plan in June 2018 during the development of the 2020 GSP. This plan was updated as part of the 2024 GSP amendment process and renamed the Eastern San Joaquin Communication and Engagement Plan (C&E Plan). The ESJGWA supported the update of this Plan (see Appendix 1-H) for the San Joaquin Subbasin, which details communications and engagement recommendations for GSAs to consider as the GSP continues to be implemented and the needs of interested parties in the region evolves. The original goals of the Outreach and Engagement Plan are still relevant in the recent iterations of this plan:
• Keep interested list of stakeholders informed and aware of opportunities for involvement through email communications and/or their preferred mode of communication • Engage DWR for facilitated support to aid in the development of the GSP • Open ESJGWA planning efforts to the public with agendas and meeting minutes published on the ESJGWA website
EXHIBIT 1
799
2024 Groundwater Sustainability Plan Amendment 1-51
Agency Information, Plan Area, and Communication November 2024 • Inform and obtain comments from the general public through public meetings held on an approximately quarterly basis
• Facilitate productive dialogue among participants at Advisory Committee, Workgroup, and public meetings through the use of qualified facilitators to obtain, consider, and integrate feedback accordingly throughout the planning process
• Seek the input of interest groups during the implementation of the GSP and any future planning efforts • Obtain input about preferred locations to conduct public informational meetings to reach diverse audiences and disadvantaged communities
• Provide timely and accurate public reporting of planning milestones through the distribution of outreach materials and posting of materials on the ESJGWA website for the GSP • Secure quality media coverage that is accurate, complete, and fair • Maintain an active communications tracking tool to capture stakeholder engagement and public outreach activities and to demonstrate the reporting of GSP outreach activities The ESJGWA used various methods to engage with and solicit input from interested parties during the 2020 GSP development process. In order to evolve the updated C&E Plan with the needs of the community, the development process started with a review of previously established commitments made by Subbasin GSAs and the ESJGWA in various SGMA-related documents and by the needs and ideas presented by interested parties. Seven individual or small group interviews were conducted between March and July of 2023 with key interested parties in the Subbasin to gather feedback on communication and engagement strategies taken during GSP implementation. Interviewees represented diverse interests, including disadvantaged communities, municipal and industrial, agricultural, domestic well, and those representing environmental water users.

Gaps or inefficiencies throughout GSP implementation were identified, showing a consistent lack of adequate support in key areas:
• Concerns over Demand Management Program: Respondents expressed concerns about potential demand reduction strategies that could be overly restrictive and disruptive to their lives and livelihoods. • Lack of Clarity on Sustainability Approaches: There was a perceived lack of clear answers and progress regarding long-term sustainability approaches.
• Cost Concerns: High water management costs and increased water rates were a concern, indicating a lack of public understanding around GSAs approach to funding. • Bureaucratic Processes: Respondents noted overly bureaucratic processes that might limit the effectiveness of the GSAs and the ESJGWA if things escalate beyond the local level. • Lack of Consistency and Transparency: There was a significant lack of consistency and transparency, particularly in how, where, and when GSAs share information and engage with each other and the public.

In order to address these key areas, the C&E Plan details the following strategies that could be implemented or expanded:
• Communications and Engagement Tracker: A strategy that involves the GSAs establishing a record-keeping system to catalogue the type and timing of outreach activities, enhancing their level of organization and compliance with requirements, with the support of the ESJGWA where necessary and feasible.

EXHIBIT 1
800
2024 Groundwater Sustainability Plan Amendment 1-52
Agency Information, Plan Area, and Communication November 2024 • Outreach Toolkit: A comprehensive approach by the GSAs to create a suite of standardized outreach materials and a library of relevant guides, aiming to ensure consistent messaging and best practices in communications and engagement, with the support and coordination of the ESJGWA. • Interested Parties Database: GSAs create a shared and comprehensive database, supported by the ESJGWA, to distribute information tailored to different jurisdictions and audiences, with the database managed by a third-party platform for easy maintenance, access, and tracking of public engagement. • Targeted Outreach: GSAs, in compliance with applicable regulations, implement specific efforts to identify, contact, educate, and engage with underrepresented groundwater users and non-English speakers on groundwater resource management, with coordination and collaboration support from the ESJGWA. • Workgroups and Committees: GSAs, in compliance with applicable regulations, consider establishing a committee or workgroup focused on small and underrepresented communities to engage on well protection and other related projects affecting these groundwater users, with support from the ESJGWA, • Native American Heritage Commission: GSAs submit and receive a Tribal and Sacred Land tribal contact list to the Native American Heritage Commission, ensuring they stay informed and in contact with recognized Indigenous communities in the region, a core component of inclusive engagement, especially for project implementation, with support from the ESJGWA
• Website Management: GSAs, in compliance with applicable regulations, establish and maintain web pages on their own or the ESJGWA websites, containing clear and accessible information, updates, and resources related to groundwater management, with the choice of management depending on the GSAs’ comfort and discretion.
• Enterprise Management System Management and Transparency: GSAs and/or the ESJGWA, in compliance with applicable regulations, maintain a catalog of data management systems and publish their methodology for maintaining and using the collected data, ensuring full transparency. • Comment Portal: GSAs and/or the ESJGWA, in compliance with applicable regulations, establish, maintain, and respond to public comments through an email contact portal, which collects data on the commenter and allows for categorization of comments, with links to the portal clearly available on their websites. • Funding and Financing: ESJGWA, in compliance with applicable regulations, coordinate with its member agencies to evaluate funding, grant, or in-kind support resources for facilitation, media relations, or outreach coordination services, supporting the addition of new staff or a dedicated outreach coordinator for the Subbasin to enhance communications and engagement efforts related to GSP implementation. • Outreach Coordinator: Recommendation to contract with an outreach coordinator to assist the ESJGWA and its member agencies with the tactics listed in the C&E Framework and any other ongoing communications and engagement efforts in the Subbasin, in compliance with all applicable codes and regulations.

1.3.4.2.2 ESJGWA Website
The ESJGWA website has been online since 2018 and continues to be maintained on a regular basis at www.esjgroundwater.org. It contains an introduction to SGMA, details on member agencies, and ESJGWA Board updates with meeting information and materials posted regularly. There are detailed sections for GSP resources, technical reports and data, educational materials, and meeting notices with the accompanying presentation materials and minutes. A section of the website is devoted to press releases, newsletters, public notices, and other major events and accomplishments. Contact information is readily available for interested parties to communicate with ESJGWA members and staff, and members of the public can subscribe to the ESJGWA mailing list to receive updates on GSP EXHIBIT 1
801
2024 Groundwater Sustainability Plan Amendment 1-53
Agency Information, Plan Area, and Communication November 2024 development and outreach events. Improvements to the website itself and the approach for its use will be continuously updated to meet the public engagement goals of the Subbasin.

1.3.4.2.3 Stakeholder Database
The ESJGWA developed a database of stakeholders who represent the region’s interests, perspectives, and geography. The database was developed by leveraging existing stakeholder lists and databases from prior Eastern San Joaquin Subbasin engagement efforts, conducting new research, and obtaining referrals from key stakeholders and stakeholder groups.

During the initial development of the stakeholder database, the ESJGWA worked with those responsible for implementing the GSP to obtain contact lists of interested parties within the Subbasin as well as other diverse contact lists they maintain.

This robust stakeholder list of interested parties includes, but is not limited to, the following:
• Community water systems
• Agricultural well owners
• Domestic well owners
• Municipal well operators
• Groundwater users (including agricultural)
• Local land use planning agencies
• Government agencies
• Nonprofit organizations
• Environmental organizations
• Higher education institutions
• Community based organizations
• Neighborhood organizations
• California Native American Tribes
• Disadvantaged communities
• Private citizens
The Stakeholder Database has been regularly updated by adding additional parties who expressed interest at public meetings and through website signups. Contacts were updated or removed as needed. The database continues to serve as the foundation for targeted outreach and communication and was also used to:
• Provide a single repository to collect, store, and organize information on Subbasin stakeholders • Allow individuals to self-identify their SGMA interests when they sign up as an interested stakeholder • Identify the interests and concerns of organization contacts and individual stakeholders EXHIBIT 1
802
2024 Groundwater Sustainability Plan Amendment 1-54
Agency Information, Plan Area, and Communication November 2024 • Plan meetings and send notices to stakeholders based upon their identified interests and role • Document all stakeholders invited to GSP development meetings and their primary input at the meetings • Post meeting agendas and minutes
• Produce communication and engagement summary reports
Table 1-5 provides a summary breakdown of the number of parties and interests represented in the Stakeholder Database.

Table 1-5: Stakeholder Database Summary
Eastern San Joaquin Groundwater Authority Stakeholder Database Interest Represented Number of Stakeholders
Government Agency (i.e. County, State) 64
Business (i.e. Consultant, Local Business, Legal
Representation) 41
Nonprofit (i.e. Environmental Organization, Thinktank) 5 Higher Education 3
Community Based Organization (i.e. Farm Bureau) 2
Water Purveyors (i.e. Public Utilities, Irrigation Districts) 77 No Affiliation Provided 93
Total 285
Outreach materials promoting informational open house events were distributed via email to the stakeholder database, and hard copies were distributed to this list throughout implementation process since the 2020 GSP.

The following section describes the stakeholder education and outreach activities completed during the development of the 2024 GSP Amendment.

1.3.4.2.4 Stakeholder Education and Outreach
Recognizing that an inclusive outreach and education process supports the success of a well-prepared GSP, the ESJGWA has prioritized stakeholder involvement and outreach in plan development and implementation, dedicating staff and financial resources for this high‐priority effort. • The ESJGWA held two public Stakeholder Advisory Workgroup (SAW) meetings and one informational open house event devoted to SGMA outreach and providing information to the public on the 2024 GSP Amendment development process. The purpose was to provide participants with information on GSP development, seek feedback from stakeholders and the public, provide a forum for the public to interact with their GSA representatives, and address questions in a transparent manner. These events were held on an approximately quarterly basis in different locations throughout the Subbasin, as listed below. o June 26, 2024 – Robert J. Cabral Agricultural Center, Stockton (23 attendees) o July 17, 2024 – Robert J. Cabral Agricultural Center, Stockton (18 attendees) o September 25, 2024 – Robert J. Cabral Agricultural Center, Stockton (40 attendees) • Additionally, GSA member agencies hosted local informational community meetings related to the SGMA process and to publicize the release of the Public Draft GSP for public comment.

EXHIBIT 1
803
2024 Groundwater Sustainability Plan Amendment 1-55
Agency Information, Plan Area, and Communication November 2024 • Individually, member GSAs provided targeted outreach materials to their constituencies through the distribution of outreach and informational materials
• Community events, including guided tours of facilities for the community, grower outreach meetings, and a tour for community leaders, were held to promote recharge projects and plans, and discuss challenges. • Member GSAs provided SGMA and project related updates to their Boards and other leadership bodies, including the Water Advisory Committee and the Linden-Peters Chamber of Commerce. • Factsheets, email announcements, and newsletters were used to raise awareness about topics and events relevant to the GSP and SGMA.
• Social media channels, such Facebook, were used to distribute targeted information relevant to SGMA, the GSP, and specific projects.
• Comment cards, provided in postcard format at the public informational open house, allowed the public and stakeholders to contribute written comments, solicit additional information, make suggestions, and submit other feedback as appropriate.

1.3.4.2.5 Incorporation of Stakeholder Feedback
The development of this GSP was informed and supported by stakeholder feedback, which was documented, addressed, and incorporated at numerous points throughout the development process. The public was invited to provide input at each Steering Committee and ESJGWA Board meeting. Information provided for GSP development was refined based on input from public meetings. Stakeholder involvement was additionally supported through the two public meetings and the open house held in September 2024 to solicit input on the draft Amended GSP from a wide range of beneficial users of groundwater in the Subbasin. Questions raised by participants at these meetings were addressed and, as needed, follow-up content presented and discussed at subsequent meetings.

In addition to influencing GSP development and decisions related to groundwater management, feedback from stakeholders played a key role in enhancing education and outreach efforts, and the stakeholder involvement process more broadly. Interviews in the initial stages of the C&E Plan development and survey responses received during the later stages, both provided valuable insight into how engagement can be improved. The second in-person SAW meeting also yielded some feedback, centering on two areas. • How to fund efforts toward sustainability, both at the GSA level and the ESJGWA level. • How to increase involvement of more diverse interests beyond water managers.

1.3.4.2.6 Draft 2024 GSP Amendment Public Comment Review Period The Public Draft 2024 GSP Amendment was posted on the ESJGWA website for a 31-day public comment period from October 1, 2024 through October 31, 2024. Notices and press releases were provided in English and Spanish publicizing the public comment period and inviting members of the public to attend the September 2024 informational open house event for more information. This event was scheduled to align with the release of the Public Draft 2024 GSP Amendment to provide a forum for the public to receive information, ask questions, and provide input. Hard copies were made available upon request.

The ESJGWA received 52 public comment submissions from a range of interested parties, including non-government organizations, neighboring subbasins, ESJGWA GSAs, state and federal agencies, and others. These individuals and organizations are listed below, and comments are provided in Appendix 1-I. • Barton Ranch, Inc.

EXHIBIT 1
804
2024 Groundwater Sustainability Plan Amendment 1-56
Agency Information, Plan Area, and Communication November 2024 • Calaveras County Water District
• California Department of Fish and Wildlife
• City of Stockton
• Sierra Club, Delta-Sierra Group
• NV5
• Restore the Delta
The PMC was responsible for reviewing and summarizing public comments, and drafting proposed response to comment recommendations for approval by the ESJGWA Board. The ESJGWA’s responses to comments are provided in Appendix 1-J.

1.3.5 Inter-basin Coordination
As part of the SGMA process, stakeholder outreach includes inter-basin coordination efforts. To date, ESJGWA has participated in the San Joaquin Valley Point of Contacts (SJC POC) meetings hosted quarterly, as well as initial introductory meetings with its neighboring subbasins. Given that the ESJ Subbasin was the first of its neighbors to submit a plan, the majority of neighboring basins were not in a position to begin meaningful coordination until recently.

There have been discussions about the establishment of annual meetings between representatives of the ESJGWA and the neighboring subbasins to begin a more formal coordination process. The purpose of these coordination meetings will be to share and discuss elements relevant to the subbasins, including water budget estimates, boundary flow assumptions, shared interconnected surface waters, and minimum thresholds.

A summary of the initial inter-basin coordination meetings with neighboring subbasins is below. • Cosumnes Subbasin – April 15, 2019
• Tracy Subbasin – June 20, 2019
• Modesto Subbasin – July 10, 2019
• South American, Solano, and East Contra Costa Subbasins – July 19, 2019 • Tracy Subbasin – September 25, 2024
To establish these annual coordination meetings, the ESJGWA plans to reach out to neighboring subbasins as part of GSP implementation to set more formal coordination between neighboring subbasins.

1.3.6 Notice of Intent to Adopt the GSP
A Notice of Intent (NOI) to adopt a GSP was signed by the Plan Manager on behalf of the GSAs and distributed on July 24, 2024. The NOI was posted to the ESJGWA website homepage and hard copies were mailed cities and counties within the Subbasin, including the following:
• County of Calaveras
• County of Stanislaus
• County of San Joaquin
• City of Escalon
EXHIBIT 1
805
2024 Groundwater Sustainability Plan Amendment 1-57
Agency Information, Plan Area, and Communication November 2024 • City of Manteca
• City of Ripon
• City of Stockton
The signed NOI is provided in Appendix 1-K.

EXHIBIT 1
806
2024 Amended Groundwater Sustainability Plan 2-1
Basin Setting November 2024

2. BASIN SETTING
This Basin Setting chapter contains three main sections as follows:
• Hydrogeologic Conceptual Model – Section 2.1 (Hydrogeologic Conceptual Model) provides the geologic information needed to understand the framework under which water moves through the Subbasin. It focuses on geologic formations, aquifers, structural features, and topography. • Current and Historical Groundwater Conditions – Section 2.2 (Historical Groundwater Conditions) and Section 2.3 (Current Groundwater Conditions) describe and present groundwater trends, levels, hydrographs and level contour maps, estimated changes in groundwater in storage, identify groundwater quality issues, address land subsidence, and address surface water interconnection. • Water Budgets – Section 2.4 (Water Budgets) describes the data used to develop the water budget. This section also discusses how the water budgets were calculated and provides water budget estimates for historical conditions, current conditions, and projected conditions.

2.1 HYDROGEOLOGIC CONCEPTUAL MODEL

2.1.1 Data Compilation
This section describes the hydrogeologic conceptual model (HCM) for the Eastern San Joaquin Subbasin (Subbasin), as was included in the 2020 Groundwater Sustainability Plan (GSP) and reconsidered during the 2024 Periodic Evaluation. The regulatory framework is based on the California Code of Regulations (CCR) Title 23 § 354.14. The HCM presents the physical characteristics used to define water movement throughout the Subbasin.

Data supporting development of the Eastern San Joaquin Subbasin HCM is available to the public from a variety of local, state, and federal agencies, as well as from non-governmental entities. The data presented herein were compiled from numerous studies conducted in the eastern portion of the San Joaquin Valley (SJV). Information from several online databases that support ongoing monitoring and development of the groundwater resources within the Eastern San Joaquin Subbasin and across California were amassed, digitized, evaluated, and reconfigured in support of the HCM. Most information was compiled during the development of the 2020 GSP. Where new data available between 2020 and 2024 provide additional information to the HCM, it has been incorporated into this chapter. New data support the original understanding of the Subbasin HCM and therefore, the original HCM remains in the 2024 GSP with additional detail incorporated where additional insights can be made.

To accomplish the data compilation task, software programs such as Microsoft Excel, ArcGIS, QGIS, CrossView, and Python1 platforms for entering, storing, displaying, and evaluating the volume of data available were used. The following subsections describe the online programmatic databases from which much of the data were sourced and provide insight on the unique obstacles within each.

2.1.1.1 Groundwater Level Data
The California Statewide Groundwater Elevation Monitoring (CASGEM) and San Joaquin County monitoring well networks provided the basis for determining groundwater levels across the Eastern San Joaquin Subbasin in the 2020 GSP. CASGEM maintains a website that allows users to download site locations and groundwater level information.

San Joaquin County’s monitoring well data came from the San Joaquin County Flood Control and Water Conservation District (SJCFCWCD).
1 Python version 3.11 was used as well as the Pandas, NumPy, Matplotlib, GeoPandas, Rasterio, Shapely, and cmocean packages
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Since the 2020 GSP, all groundwater level data have been centralized in the California Department of Water Resource’s (DWR) Water Data Library (WDL) database. Well information can be found in WDL, and all available historical data can be downloaded for each well.

There are approximately 1,000 unique wells across the Eastern San Joaquin Subbasin. Despite the large number of wells, horizontal and vertical data gaps still exist. Large areas of the Subbasin contain very few wells, particularly in the northwest and southeast portions of the Subbasin (see Figure 2-1).Substantial efforts have been made to fill these data gaps since the 2020 GSP. Section 7.1 describes what has been done as part of GSP implementation between 2020 and 2024 to address these gaps.

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Figure 2-1: Depth of All Wells in Water Data Library
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Figure 2-2 shows the distribution of well depths of WDL wells within the Subbasin, a large number of which do not have construction depth or screen interval information. This makes determining groundwater levels for depth-discrete aquifer intervals impossible. Groundwater elevation contour maps were prepared for the Subbasin’s single principal aquifer, consistent with CCR Title 23 § 354.16 Groundwater Conditions requirements. Despite uncertainties due to limited construction information, this GSP presents maps that provide a useful description of groundwater conditions.

Figure 2-2: Depth Distribution of Wells in Water Data Library

2.1.1.2 Groundwater Quality Data
This GSP relies on groundwater quality data from the Groundwater Ambient Monitoring and Assessment (GAMA) Program. GAMA includes water quality data from numerous sources, such as United States Geological Survey (USGS) and DWR. The GAMA database contains approximately 6,800 well sites throughout the Eastern San Joaquin Subbasin with over 1.6 million water quality measurements (Figure 2-3).

Although GAMA provides data on many groundwater parameters and wells throughout the Eastern San Joaquin Subbasin, significant data gaps remain. For instance, there are inconsistencies in the parameters measured, as well as in the sampling periods. Some wells are sampled at regular intervals (i.e., quarterly or annually), while others are sampled irregularly. Such assorted schedules make analysis over a given period of time difficult. Data gaps are also apparent when looking at parameters over a longer timeframe. For example, chloride, an important and commonly measured groundwater quality parameter, is reported in only a small fraction of the total number of GAMA wells. As shown in Figure 2-4, out of the over 6,800 wells listed in GAMA for the Eastern San Joaquin Subbasin, no more than 700 chloride measurements were taken during any year since 2005.

No new groundwater quality sources have been identified since the development of the 2020 GSP that are as comprehensive as GAMA.
0 50
100
150
200
250
300
350
400
No Depth Data 0- 100 100-250 250 - 500 > 500
Number of Wells
Depth (ft.)
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Figure 2-3: GAMA Monitoring Well Network
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Figure 2-4: Number of Chloride Measurements Taken at GAMA Monitoring Sites (2005-2017) Below is a list of attributes for each groundwater quality result in GAMA:
• Well ID
• Results
• Chemical
• Units
• Qualifier
• RL (Reporting Limit)
• Approximate Latitude
• Approximate Longitude
• Well Type
• Well Depth
• Top of Screen
• Screen Length
• Source
• Source Name
• Other Names
The attributes of each well in the GAMA database are not always complete or accurate. Well depths and screen interval data, where available, promote vertical analysis of groundwater quality data because these data can be correlated to depth-discrete aquifer zones. Additional depth-specific water quality monitoring is a focus of the monitoring network for this GSP, as discussed in Chapter 4 of this GSP.

2.1.1.3 Stratigraphic Data
The Online System for Well Completion Reports (OSWCR) provided a majority of the groundwater well logs used in developing the HCM. This online database, developed and maintained by DWR, is a compilation of well completion reports accessible to the public for viewing and downloading. Tables of water well records are also available which contain attributes such as construction depth and well type (e.g., domestic or agricultural). However, not every well record is complete within the tables or only a few attributes may be listed. None of the stratigraphic or geologic data are provided in the tables. Stratigraphic or geologic data must be obtained from the individual well completion reports, which are only available as scanned images downloadable in portable document format (pdf). Once the well completion reports are retrieved from the database, the geologic information can then be manually digitized into Microsoft Excel or other database software.

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Critical information needed from the well completion reports are construction depth, screen interval, and borehole stratigraphy. The quality and completeness of the reports are, however, highly variable. Very few well logs contain all of the critical data; many more list only a few of the key attributes or none at all. Descriptions of the borehole stratigraphy also vary widely, from comprehensive geologic descriptions to single-word captions (e.g., sand, sandstone, or clay).

Given the volume of wells in the Eastern San Joaquin Subbasin and the critical importance of the data being retrieved, great attention was paid to this aspect of the data compilation effort.

Once compiled, the well construction and stratigraphic data from OSWCR were correlated with well data available from the CASGEM and San Joaquin County monitoring well databases. To accomplish this task, individual well logs from OSWCR were assigned a unique location and then matched to a specific well within the CASGEM and San Joaquin County datasets (CA DWR, 2000).

Although the State ID format does not allow for matching between OSWCR, CASGEM, and San Joaquin County databases, well completion reports from OSWCR were correlated to wells in the other databases. This connection was made by plotting CASGEM/San Joaquin County well locations in Geographic Information System (GIS) software and correlating well completion reports to nearby wells with similar attributes. For instance, the State ID of the CASGEM/San Joaquin County wells and the modified State ID of the OSWCR were used to locate the features within the same Township/Range/Section. Well completion reports were matched to wells by attributes such as screen interval and seal depth or based on written location descriptions or hand-drawn sketches of the location.

To further support spatial analysis, well completion reports from OSWCR with no corresponding well in any database were added to the data set. Well completion reports for wells from other sources, including USGS nested wells and municipal wells, were also added. Well completion reports from OSWCR that did not correspond to wells in a different database were plotted using latitude and longitude coordinates listed in OSWCR. These coordinates are often approximations of the actual location; many latitude and longitude values are the geometric center of the section containing each well. All totaled, the borehole stratigraphy from approximately 330 groundwater wells was digitized to provide horizontal spatial coverage.

While groundwater wells provide valuable data in the shallower portion of the basin that are mostly accessed for groundwater use, the hydrostratigraphic units within the Eastern San Joaquin Subbasin are much deeper, reaching a maximum depth of approximately 1,000 feet. Data from the Division of Oil, Gas, and Geothermal Resources (DOGGR) were used to assess the geologic strata at the depths important to the HCM, as these wells are typically much deeper than groundwater wells.

Interpretation of geologic formations from the well completion reports and DOGGR well logs was undertaken after digitizing stratigraphic data from the various sources. This process relied heavily on the distinguishing features of each formation (Section 2.1.5), surficial geologic maps (Section 2.1.5), location and depth of borehole (Section 2.1.7), and professional judgement.

2.1.1.4 Airborne Electromagnetic (AEM) Surveys
Airborne Electromagnetic (AEM) surveys were completed across the state since the 2020 GSP. The data collected provides additional data to inform the HCM of the surveyed basins. Data are collected from a helicopter carrying geophysical equipment on a large hexagonal frame about 30 meters above the ground. This equipment sends a weak electromagnetic signal into the ground and measures the response received back. An electrical resistivity profile of the subsurface down to depths of as much as 300 meters can be developed using the received data. The Eastern San Joaquin Subbasin was included in Survey Area 6, which also included the Cosumnes, Tracy, and East Contra Costa Subbasins and Livermore Valley Groundwater Basin.

Figure 2-5 shows where the survey’s flight lines were completed across the Subbasin (CA DWR, 2023 and CA DWR, 20024).

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Aquifers are typically composed of sands and gravels that have high resistivities, while aquitards are composed of silt and clays that have low resistivities. The resistivity profiles help in mapping the overall dimensions and extent of the aquifer systems. The AEM survey data is analyzed in detail, correlated with data from nearby wells, and modeled to produce subsurface maps of the resistivity, lithology (the physical characteristics of rocks), and an initial hydrostratigraphic model (a description of the water-bearing and water-confining properties of rocks). Well lithology and oil and gas well geophysical logs located along the AEM flight lines were compiled to provide additional data to support the surveys. Groundwater levels and water quality data were also compiled.

DWR processed the collected AEM data to filter out potential noise in the data and, if necessary, remove the data where interference is too great to effectively interpret. Resistivity models were produced that provide profiles indicative of areas with relatively coarser-grained (sands and gravels) and finer-grained (silts and clays) material, represented by areas of higher and lower resistivities, respectively. The resistivity data were then processed, combining the detailed high-quality well lithologic data with information on the spatial heterogeneity from the resistivity to provide an interpretation of lithology. The resistivity and coarse fraction data were combined to produce an initial hydrostratigraphic model for each subbasin, designating areas or layers of the subsurface having similar hydrogeologic properties (Department of Water Resources (CA DWR), 2023).

The resistivity data, and the texture interpretation DWR developed, are useful as an additional source of information to contribute to local understanding of the Subbasin’s hydrogeology and structural features. These data were incorporated into the following pieces of the GSP:
• New cross-sections in the HCM
• Additional shallow subsurface texture map included in the HCM • Refinements to the model stratigraphy in ESJWRM, described in detail in the ESJWRM Version 3.0 Model Documentation TM included in Appendix 2-C.

Python was used to process the data provided by DWR.

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Figure 2-5: AEM Flight Lines across ESJ Subbasin

2.1.1.5 GIS Data
In accordance with CCR Title 23 §354.14, maps of various basin attributes are required as part of the HCM. To produce these maps, GIS software was used to store, manage, and analyze spatial and tabular data. GIS software was also used to extrapolate data through complex processes in cases where information or guidance was limited. For example, in accordance with CCR Title 23 §354.16, groundwater elevation contour maps are required based on the best available information. This requirement does not specify methods to use for producing the data, but the DWR Best Management Practice (BMP) for HCM suggests techniques used in Tonkin, M. and Larson, S. (2002), which uses geostatistical methods in conjunction with logical interpretations of groundwater level data to provide an adequate level of detail and accuracy.

Certain GIS software programs, including QGIS and ArcGIS, were relied on heavily. QGIS is a powerful open-source program, whereas ArcGIS is the industry standard. Both are capable of completing the required elements for the GSP.

QGIS provided the graphical capabilities for final map production. ArcGIS was specifically utilized because of a thirdparty extension, CrossView, which is capable of generating hydrogeologic cross-sections that are presented in Section

2.1.7. The Universal Transverse Mercator (UTM) coordinate system and North American Datum of 1983 (NAD 83) were utilized along with the North American Vertical Datum of 1988 (NAVD 88) for all spatial data.

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2.1.2 Regional Geologic and Structural Setting
The Eastern San Joaquin Subbasin lies within the San Joaquin Valley, which is part of the Central Valley of California.

The Central Valley is a 400-mile-long, 50-mile-wide, northwestward trending asymmetrical structural trough filled with geologic units deposited over a long period of time. See Table 2-2 (Section 2.1.5) for the generalized stratigraphic column and Figure 2-6 below for the geologic time scale. The Sierra Nevada Mountain Range, east of the Central Valley, consists of pre-Tertiary igneous and metamorphic continental rocks. The Coast Range, to the west, consists of pre-Tertiary and Tertiary semi-consolidated to consolidated marine sedimentary and continental rocks. The material sources for the Central Valley continental deposits are the Coast Range and the Sierra Nevada, which are composed primarily of granite, related plutonic rocks, and metasedimentary and metavolcanic rocks from Late Jurassic to Ordovician age (Bertoldi et al., 1991).

Figure 2-6: Geologic Time Scale
Millions of
Years Ago
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2.1.3 Geologic History
The origin of geologic formations within the Eastern San Joaquin Subbasin varies in geologic time ranging from recent to Pre-Cretaceous bedrock or basement. Six to 10 miles of sediment have been deposited within the Central Valley and include both marine and continental deposits consisting of gravels, sands, silts, and clays. During the middle Cretaceous (~100 million years ago), parts of the Central Valley were inundated by the Pacific Ocean resulting in deposition of marine deposits. Marine conditions persisted through the middle to late Tertiary period (~3-30 million years ago) after which time sedimentation changed from marine to continental deposits due to the retreat of the sea and the regional rising of land mass previously inundated by the ocean. Intermittent volcanism dominated with the deposition of rhyolites and andesites (CA DWR, 1967).

2.1.4 Near-Surface Conditions

2.1.4.1 Topography
Ground surface elevations vary extensively across the Eastern San Joaquin Subbasin, from almost 1,000 feet above mean sea level (MSL) in the upland areas in the east to around sea level in the flat lying valley floor to the west. The Eastern San Joaquin Subbasin topographic map is provided as Figure 2-7.

The modern-day physiographic features are a direct result of the geologic history of the region. Surficial features on the valley floor in the Eastern San Joaquin Subbasin can be divided into physiographic units as described by DWR (1967) and Burow and others (2004): river flood plains, channels, and overflow lands; low alluvial plains and fluvial fans; and dissected uplands. The dissected uplands lie along the flanks of the valley between the Sierra Nevada to the east and the alluvial plains and fluvial fans to the west. Local relief ranges in excess of 100 feet in the form of dissected hills and gently rolling lands. The most extreme slopes are observed in Calaveras County, which are steeper than 25 percent. West of the dissected uplands is a belt of coalescing fluvial fans of low relief (less than 10 feet) that forms the low alluvial plains and fans that range in width from about 14 to 20 miles. These fans lie between the dissected uplands and the nearly flat surface of the valley trough. River floodplains and channels occur as narrow, disconnected strips along the channels of the major rivers. Overflow lands of the valley trough tributary to the San Joaquin River define the area inundated by rivers when floods are highest under natural conditions.

2.1.4.2 Major Hydrologic Features
The major hydrologic features within the Eastern San Joaquin Subbasin are shown in EXHIBIT 1
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Figure 2-8. The Subbasin is bounded on all sides except to the east by streams. Adjacent groundwater subbasins also share an interest in the impacts of the Sustainable Groundwater Management Act (SGMA) on these boundary streams.

In the Eastern San Joaquin Subbasin, the major rivers running east-west have headwaters high in the Sierra Nevada and flow west toward the axis of the valley Figure 2-8. Little deposition is taking place currently, and the rivers are cutting downward on the upper reaches of the fans where the river floodplains are commonly entrenched to depths of 50 to 80 feet. However, toward the lower ends of the fans where river gradients are low, many small streams and tributaries of the major rivers are actively aggrading their beds.

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Figure 2-7: Topography
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Figure 2-8: Major Hydrologic Features
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The San Joaquin River is the principal drainage outlet of the northern San Joaquin Valley, flowing northward on the west margin of the Eastern San Joaquin Subbasin to its confluence with the Sacramento River in the Sacramento-San Joaquin River Delta (Delta) (Burow et al., 2004). Three major westerly flowing tributaries to the San Joaquin River within or adjacent to the Eastern San Joaquin Subbasin are the Stanislaus River (Subbasin south boundary), the Mokelumne River (north portion of Subbasin), and the Calaveras River (central portion of Subbasin).

The Stanislaus River drains a watershed of about 1,040 mi2(Burow et al., 2004) and flows through the dissected uplands between the communities of Knights Ferry and Oakdale, along the low alluvial plains and fans near the City of Riverbank to the confluence with the San Joaquin River near Vernalis (see Figure 2-9). Most of the watershed area falls within Modesto Subbasin. The flow in the Stanislaus River varies seasonally from less than 134 acre-feet per day (AF/day) during the dry season in early fall to over 16,400 AF/day during wet season in winter. These flows correlate to discharges from 68 to over 8,270 cubic feet per second (cfs) recorded at the Orange Blossom Bridge gauging station approximately one mile east of Oakdale and eight miles west of the Subbasin boundary along the river (CA DWR, 2019).

The Mokelumne River drains a watershed of about 5,550 km2(2,140 mi2) and flows through the dissected uplands between the communities of Jackson and San Andreas into Pardee Reservoir where it is released to flow downstream into Camanche Reservoir and out along the alluvial plains and fans toward its confluence with the San Joaquin River near Isleton. On the north boundary of the Eastern San Joaquin Subbasin is Dry Creek and the Lower Dry Creek Watershed, the majority of which is within Cosumnes Subbasin. Dry Creek is mapped as an ephemeral drainage and is tributary to the Mokelumne River with its confluence near Thornton. Flow in the Mokelumne River below Camanche Reservoir varies seasonally and is dependent on discharges from the on-stream reservoir, from less than 200 AF/day during the dry season to 9,900 AF/day during the wet season. These flows correlate to discharges from as low as 100 to no more than 5,000 cfs reported by the USGS below the Camanche Dam. Major watersheds of the river are the Upper Mokelumne River (most of which is outside of the Subbasin to the east, with a small portion overlapping with Cosumnes Subbasin) and the Lower Mokelumne River (mostly contained in the Subbasin, with a small portion intersecting the South American and Solano Subbasins).

The Calaveras River, also with headwaters in the Sierra Nevada, drains a watershed of about 1,370 km2(530 mi2) and flows into and across the Subbasin to its confluence with the San Joaquin River on the northwest side of Stockton.

Flow in the Calaveras River below the New Hogan Reservoir varies seasonally from 608 AF/day to 19,800 AF/day and is dependent on discharges from the on-stream reservoir. These flows correlate to discharges from 223 to over 10,000 cfs reported by the USGS below the New Hogan Reservoir.

In addition to the Stanislaus, Mokelumne, and Calaveras Rivers, 10 watersheds extend into and across the Eastern San Joaquin Subbasin. Three of these watersheds extend beyond the western boundary of the Eastern San Joaquin Subbasin into the East Contra Costa or Tracy Subbasins: Middle River-San Joaquin, Five Mile Creek-San Joaquin, and Lone Tree Creek-San Joaquin. The Lone Tree Creek-San Joaquin watershed has its headwaters in the Coast Range foothills. Figure 2-9 depicts the Eastern San Joaquin Subbasin and the watersheds that overlie the Subbasin.

Table 2-1 is a list of watersheds that overlie the Subbasin.

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Table 2-1: Eastern San Joaquin Subbasin Watershed Details Watershed Name Total Area
(square miles)
Area within
Subbasin
(square miles)
Percentage of
Watershed within
Subbasin
Lower Mokelumne River 223 202 91
Lower Dry Creek 88 47 53
French Camp Slough 88 88 100
Upper Mokelumne River 93 15 16
Lone Tree Creek 158 158 100
Little Johns Creek 122 63 52
Rock Creek 107 44 41
Calaveras River 224 133 60
Middle River-San Joaquin River 213 49 23
Mormon Slough 75 75 100
Lower Stanislaus River 218 37 17
Lone Tree Creek-San Joaquin River 169 98 58
Five Mile Creek-San Joaquin River 154 62 40
Bear Creek 127 127 100
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Figure 2-9: Eastern San Joaquin Subbasin Watersheds
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2.1.4.3 Surface Soils
Soils in the Eastern San Joaquin Subbasin are one of the primary controlling factors on surface water percolation rates through the vadose zone down to the groundwater table. As described in CA DWR (1967), soils in the region of the Eastern San Joaquin Subbasin can be grouped into five main categories:

1. Alluvial fan and flood plain soils

2. Organic basin soils

3. Basin soils

4. Lower terrace soils

5. Higher terrace and upland soils
These groupings coincide in part with the geologic formations in that the oldest soils are found on the nearly level high terraces and old fluvial fans in the eastern part of the area. The oldest soils typically have claypan or hardpan layers at depths of two feet or less. The youngest soils are forming on the recently deposited alluvium along stream bottoms and on recently exposed surfaces. These soils are generally deep and rich in nutrients. The soils at intermediate stages of development are on the low terraces. Figure 2-2-10 shows the areal distribution of the five soil types in San Joaquin County (CA DWR, 1967).

Alluvial fan and floodplain deposits are
present in three areas of the Eastern
San Joaquin Subbasin bounding major
east-west rivers: Mokelumne,
Calaveras, and Stanislaus Rivers.

Figure 2-2-10 depicts soil depositional
areas within the Subbasin. These areas
have the best infiltration rates,
exclusive of the peat locales in the
Delta (northwest portion adjacent to the
Mokelumne River).

Soils of the Mokelumne and Stanislaus
River fans have young soil profiles of
sandy loam to loam. Infiltration rates of
the soils are predominantly between

0.6 to 2 inches per hour. Areas of silt
loam are also common especially in the
floodplain and have a lower infiltration
rate of less than 0.6 inches per hour.

Soils in the alluvial fans tend to coarsen
toward the apex of the fan. The soil
types show little compaction and slight
accumulation of lime or clay. Hardpan
development, which would preclude
infiltration, is minimal.

Figure 2-2-10: Soil Depositional Areas
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The soils of the Calaveras fan have deeper profiles of loam and clay loam with an infiltration rate of less than 0.6 inches per hour. These soils tend to be darker and heavier than the Stanislaus and Mokelumne River fan soils likely due to the source area being restricted to metamorphic or pre-Tertiary sedimentary material, whereas the Mokelumne and Stanislaus Rivers received large contributions from a granitic source (CA DWR, 1967).

The organic basin soils are restricted to the lower Delta portion of the Eastern San Joaquin Subbasin. Peat, muck, and clay loam are terms commonly applied to soils in this group. The organic basin soils have variable infiltration capacity.

Where peat is the dominant soil constituent, infiltration is high (greater than 2 inches per hour); where clay loam or muck occurs, infiltration is low (less than 0.6 inches per hour) (CA DWR, 1967).

The interfan and basin soils lie between the Mokelumne, Calaveras, and Stanislaus River fans in a northwesterly trending belt and around the periphery of the organic basin soils. These soils generally have well-developed profiles, medium-to-heavy textures, and fairly well compacted subsoils. Locally, hardpan overlies silty to silty clay loams.

Consequently, these soils have low infiltration rates (less than 0.6 inches per hour).

The terrace and upland soils have profiles containing moderately dense accumulation of clay and claypan, relatively near the surface. These layers are impervious barriers to the local downward movement of water, except where root holes and other breaks permit infiltration.

The Natural Resource Conservation Service (NRCS) categorizes soils by hydrologic soil groups. The hydrologic soil group is an estimation of the infiltration rate of the first five feet of soil based on depositional characteristics (mostly grain size and sorting) and secondary characteristics (compaction, lithification, and weathering). Hydrologic soil groups and their relative infiltration rates are listed below:
• A (high)
• B (medium)
• C (slow)
• D (very slow)
Figure 2-11 shows the distribution of soils mapped by hydrologic soil group across the Eastern San Joaquin Subbasin.

The broad geologic features of the Eastern San Joaquin Subbasin reflecting the river drainage elevations, areas, and percent above snowline are also apparent in the map of soils distribution. The Stanislaus and Mokelumne River alluvial fans have the overall highest infiltration rate followed by the Calaveras River fan. The smaller foothill watersheds have the lowest average infiltration rates. The relatively high permeability of windblown sands on the Mokelumne and Stanislaus River fans and the recent alluvium of the current Mokelumne and Calaveras River floodplains are also recognizable (Figure 2-11).

Hardpan is a strongly cemented weathering profile that limits infiltration unless it is modified by ripping or excavating.

Some hardpan is discontinuous and relatively shallow (located at a depth of five feet or less) and often is ripped with a bulldozer for agricultural purposes. However, in other areas, particularly in the older pre-Modesto formations, the hardpan is more continuous and extends to depths that cannot be reached by ripping methods.

The Farmington Groundwater Recharge/Seasonal Habitat Study Final Report, prepared by Montgomery Watson Harza (MWH) and dated August 2001 (MWH, 2001), overlaid the NRCS’s interpretation of where hardpan soils would be found under natural conditions. The extent of the thickest hardpan is shown in Figure 2-12 in dark blue cross hatching.

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Figure 2-11: Hydrologic Soil Groups
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Figure 2-12: Occurrence of Hardpan within the Eastern San Joaquin Subbasin EXHIBIT 1
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2.1.4.4 Imported Water
The Eastern San Joaquin Subbasin does not rely on imported water supplies. All surface water used within the Subbasin originates from sources either within or directly tributary to the Subbasin. Several districts receive surface water from the Stanislaus River with a point of diversion approximately four miles upstream of the eastern boundary of the Subbasin (located in the Sierra Nevada foothills and not part of a Bulletin 118 groundwater basin). While this diversion point occurs outside of the Subbasin boundary, this water naturally enters the Subbasin by diversion or by surface-groundwater interaction.

2.1.4.5 Groundwater Recharge and Discharge Areas
Groundwater recharge and discharge is driven by both natural and anthropogenic (human-influenced) factors. Areas of recharge and discharge within the Eastern San Joaquin Subbasin are discussed below. Quantitative information about all natural and anthropogenic recharge and discharge is provided in Section 2.4.

2.1.4.5.1 Description of Recharge Areas
The recharge potential of soils and formations encountered in the Eastern San Joaquin Subbasin varies considerably and is dependent on primary and secondary geologic effects. Primary geologic patterns that influence permeability relate to grain size and sorting as a result of depositional characteristics. Secondary geologic effects that influence soil recharge characteristics are associated with post-depositional events such as consolidation, lithification, and weathering, including the development of hardpan soils (MWH, 2001). Additional information on geologic formations is provided in Section 2.1.5.

The primary (original) geologic permeability of the pre-Modesto formations is variable depending on grain size, but in general is low due to secondary (post-depositional) effects including the development of hardpan soils. However, the units are heterogeneous (variable), and permeable channels are common beneath the hardpan. The primary permeability of the Modesto Formation varies both east-west and north-south due to grain size differences in the original depositional environments. On any given drainage, the alluvium is generally coarsest (and most permeable) in the east where the gradient is steepest, and the relatively high energy stream carries and deposits a high proportion of coarse bedload sand and gravel (the proximal fan). Suspended sediment (clay and silt) is generally not deposited until it is carried farther west to a lower energy environment (the distal fan). As a result, the average permeability, and thus the average recharge rates, of the alluvial fan decreases overall from east to west (MWH, 2001).

The grain size distribution produced from each watershed depends on several characteristics, including the type of geologic materials in the source area, the watershed's gradient and total area, and the portions of the watershed subject to rainfall and snowmelt runoff. During the Pleistocene Epoch when the Modesto and Riverbank formations were deposited (approximately 1 million to 10,000 years ago), a colder, wetter climate produced a lower snowline than at present, and coarse glacial outwash dominated the major streams originating in the interior of the Sierra Nevada (Mokelumne and Stanislaus River fans). Alluvium of the smaller foothill watersheds consists primarily of fine-grained material in interfan areas (Bear Creek and Little Johns/Rock Creek drainages). The Calaveras River drainage is intermediate between the two, forming a moderately coarse alluvial fan between the Calaveras River and Mormon Slough (MWH, 2001). Figure 2-13 depicts the aerial extents of the alluvial fans, interfan areas, and pre-Modesto formations.

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Figure 2-13: Areal Extents of Alluvial Fans, Interfans, and Pre-Modesto Formations EXHIBIT 1
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Within this overall framework, the alluvial fans of each drainage contain coarse-grained channel and levee deposits of relatively high permeability within finer-grained overbank and floodbasin deposits of low permeability. Stream channels migrate and abruptly jump to new locations over time in this depositional environment, creating deposits that are heterogeneous both laterally and vertically. As a result of this depositional environment, localized silt and clay lenses are common even in the alluvial fan areas. However, no regional clay layer is expected to exist that would severely reduce or inhibit vertical migration of water. The recent (Holocene) alluvium in the current incised river floodplains (Mokelumne and Calaveras Rivers) and windblown (eolian) sand deposits are of limited extent but relatively permeable (MWH, 2001). These present and historical alluvial depositional factors are useful in understanding rainfall percolation rates when the soil moisture deficit is zero and groundwater recharge occurs; groundwater system preferential vertical movement pathways through the principal aquifer and aquitards; and future groundwater management alternatives.

The Eastern San Joaquin Water Resources Model (ESJWRM) estimates the recharge that occurs in different areas of the Eastern San Joaquin Subbasin, largely due to the percolation of rainfall and applied irrigation water. Figure 2-14 shows the spatial distribution of percolation in the Subbasin, with generally less percolation occurring in finer soil areas (e.g., Hydrologic Soil Group D) and areas without extensive irrigation (i.e., native landscape). The higher percolation areas are those that substantially contribute to the replenishment and recharge in the Subbasin. Section 1.2.2.9 describes conjunctive use programs that were in place prior to the implementation of SGMA, and Figure 1-16, shown previously in Chapter 1: Agency Information, Plan Area, and Communication, maps direct recharge areas in the Subbasin.

DWR’s texture interpretation of the AEM data provided an additional data source for evaluating near-surface conditions in terms of percent coarseness of the material. Figure 2-15 shows the average percent coarseness (coarse fraction) in the top 50 ft of the subsurface along the survey flight lines. Darker blues represent finer material, while greens and yellows represent coarser material. On the eastern side of the Subbasin, where the alluvial fans identified in Figure 2-13 lie, the resistivity data indicate that the near-surface material is relatively coarser than in other areas of the Subbasin. This is consistent with general understanding of alluvial fan structure, where coarser materials are found further east where the gradient is higher. Increasingly to the west, the material becomes increasingly finer. Resistivitybased coarse fraction data complements ESJWRM model output, Hydrologic Soil Group mapping, Soil Agricultural Groundwater Banking Index (SAGBI) mapping, and geologic maps to identify areas in which natural groundwater recharge is occurring.

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Figure 2-14: Existing Areas of Groundwater Recharge (ESJWRM Version 3.0) Note: Figure shows the distribution of deep percolation of precipitation and applied water based on ESJWRM Version 3.0 model outputs. It does not include recharge from rivers and streams, boundary flows, or recharge projects.

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Figure 2-15: Average Percent Coarse Fraction in Near-Surface Materials

2.1.4.5.2 Description of Discharge Areas
Groundwater discharge primarily occurs through groundwater production wells. Groundwater production in Eastern San Joaquin Subbasin is discussed further in Section 2.2. Groundwater also discharges to rivers and streams where groundwater elevations are higher than river stage. Other sources of groundwater discharge are evapotranspiration from riparian areas, phreatophyte woodlands, and other groundwater-dependent ecosystem (GDE) communities.

Groundwater discharge to streams is described more in Section 2.2.6 and discusses analyses based on modeling results from the ESJWRM for approximately 1,700 stream nodes (locations along simulated streams where calculations are made related to stream flows and interaction with groundwater) in the Eastern San Joaquin Subbasin.

2.1.4.5.3 Description of Potential Recharge Areas
Figure 2-16 shows areas with their potential for groundwater recharge, as identified by the Soil Agricultural Groundwater Banking Index (SAGBI). SAGBI provides an index for the groundwater recharge for agricultural lands by considering deep percolation, root zone residence time, topography, chemical limitations, and soil surface condition.

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SAGBI data are derived from “modified” SAGBI data. “Modified” SAGBI data show higher potential for recharge than unmodified SAGBI data because the modified data assume that the soils have been or will be ripped to a depth of 6 feet, which can break up fine grained materials at the surface to improve percolation. Modified SAGBI data categorize 310,098 acres out of 610,890 acres (51 percent) of agricultural and grazing land within the Subbasin as moderately good, good, or excellent for groundwater recharge (University of California, Davis, 2018).

Figure 2-16: Potential Recharge Areas

2.1.5 Geologic Formations and Stratigraphy
Geologic formations within the Central Valley and Eastern San Joaquin Subbasin are generally grouped as either eastside or westside formations based on their location relative to the San Joaquin River and the source of the sedimentary material of which they are composed. The Eastern San Joaquin Subbasin is located to the east of the San Joaquin River. Eastside continental formation material generally originates from deposits from the Sierra Nevada and westside continental formation material generally originates from the deposits of the Coast Range. Rising land masses contributed to the erosion and deposition of alluvial sands and fan deposits. Glaciation in the Pleistocene also contributed to the steepening of streams during melt water periods (CA DWR, 1967).

The block diagram of the Central Valley (Figure 2-17) provides a generalized geologic cross-sectional view of the geologic setting. The Eastern San Joaquin Subbasin is located in the foothills margin between the roughly horizontal alluvial sediments of the Central Valley geomorphic province, labeled “Central Valley” in Figure 2-17, and the granitic Sierra Nevada geomorphic province, labeled “Sierra Nevada” in Figure 2-17.

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Sediment deposits can be subdivided into consolidated and unconsolidated deposits, with the consolidated sediments underlying the unconsolidated sediments. The most important fresh water-bearing formations in the Eastern San Joaquin Subbasin are the sands within the consolidated Mehrten and Laguna Formations and the unconsolidated younger alluvial deposits consisting of the Riverbank and Modesto Formations.

Figure 2-17: Generalized Geologic Section and Eastern San Joaquin Subbasin Setting With depth, the stratigraphy of unconsolidated sediments consists initially of Recent to Pleistocene Age alluvial deposits of the Post-Modesto deposits and the Modesto and Riverbank Formations. The sediments of these units are typically unconsolidated sands and gravels interbedded with considerable silts and clays. These clays separate the upper sediments over the lower Late Plio-Pleistocene Age Laguna Formation and the older Eocene to Pliocene Age Mehrten Formation. The Laguna and Mehrten Formations are characterized by poorly consolidated sediments and are differentiated based on color and sand type. The Laguna Formation is typically light brown, and the differentiating characteristic of the Mehrten is black sands derived from volcanic detritus. The Valley Springs and Ione Formations are encountered below the Mehrten Formation. The formations have a distinct geologic dip and thickness to the west.

The geologic map shown in Figure 2-18 illustrates the surface deposits of the Pleistocene-aged Modesto Formation and Turlock Lake Formation largely within the valley floor (Wagner et al., 1981; Wagner et al., 1991). The knolls and ridges to the east represent outcrops of the Tertiary-aged Laguna, Mehrten, Valley Springs, and Ione Formations. The geologic stratigraphic column is provided on Table 2-2.

Eastern San Joaquin Subbasin
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Figure 2-18: Geologic Map
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Table 2-2: Generalized Stratigraphic Column, Formation Descriptions, and Water-Bearing Properties Era*
Period*
Epoch* Formation &
Map Symbol
Thickness Maximum
(feet) Rock Characteristics and
Environment
Water-Bearing
Properties
Holocene Stream Channel
Deposits
50± Continental unconsolidated
gravel and coarse to medium
sand deposited along present
stream channels.

High permeability,
significant avenue for
percolation to
underlying formations.

Late Pliocene Modesto (Qm) 65-130± Continental fan and interfan material, locally some basin
types, lenticular gravel, sand,
silt, clay.

Moderate
permeabilities.

Unconfined aquifer.

Quaternary
Pliocene Riverbank (Qr) 150 to 250 Continental fan and interfan material, locally some basin
types, lenticular gravel, sand,
silt, clay. Reddish clay-rich
duripan caps the unit.

Moderate
permeabilities.

Unconfined aquifer.

CENOZOIC
Recent to PlioPleistoceneFlood Basin
Deposits (Qb)
Turlock Lake
Formation (Qtl)
0-1,000± Continental basinal equivalent
of Laguna, Tulare & younger
formations. Clay, silt & sand,
organic in part.

Generally low
permeabilities,
saturated
environment,
unconfined to
confined.

Plio-Pleistocene Laguna (Tl) 0-1000± Continental, semi-to unconsolidated silt, sand &
gravel, poorly sorted, includes
Arroyo Seco Gravel pediment
of Mokelumne R. area.

Moderate permeability,
Unconfined to locally
semi-confined.

Restricted perched
bodies in some areas.

Mio-Pliocene Mehrten (Tm) 0-600± Continental andesitic
derivatives of silt, sand and
gravel & their indurated
equivalents; tuff; breccia;
agglomerate.

Moderate permeability
to high where "black
sands" occur.

Confined to
unconfined.

Tertiary
Miocene Valley Springs
(Tvs)
0-500± Continental rhyolitic ash, clay,
sand & gravel and their
indurated equivalent.

Low permeability. Not
considered as
significant in
groundwater studies.

Eocene Ione (Tl) 0-500± Light colored clay and sand.

Marine shale, siltstone and
sandstone
Contains saline waters
except where flushed
in outcrop areas.

ZOIC
Creta-ceous
Cretaceous
Jurassic
Undifferentiated
Bedrock
Igneous, metamorphics and
ultramafics.

Contains saline
waters. Not relevant to
fresh water basin
except as possible
contaminant source.

MESO
Pre- Cretace- ous
Sources: CA DWR, 1967; Burow et al., 2004
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2.1.5.1 Geologic Formation Descriptions
The Tertiary-age units that overlie the basement rocks and generally outcrop within the Eastern San Joaquin Subbasin are discussed in the following sections, from oldest to youngest.

2.1.5.1.1 Pre-Ione Eocene Rocks
The pre-Ione Eocene rocks, as described by Chapman and Bishop (1975), were deposited in a pre-Ione bedrock paleochannel system. Their composition includes sedimentary rocks of marine origin with biotite, chlorite, and muscovite. Feldspar is a significant component of this unit (Creely & Force, 2007). The thickness of this unit is highly variable in the foothill area as it is controlled by basement complex topography. The unit “wedges out” to the east and assumes a more uniform regional thickness to the west in the Central Valley Mesozoic-Cenozoic sediment pile (Creely & Force, 2007). Depictions and full geologic formation detail are provided in Table 2-2. The Tertiary volcanic and sedimentary rocks and terrace deposits are separated from the Jurassic volcanic/metamorphic basement by an angular unconformity from small-scale faulting. The Franciscan Group, Cretaceous, and Eocene Undifferentiated deposits have been impacted by the east-west Stockton Fault (CA DWR, 1967).

2.1.5.1.2 Ione Formation
The Eocene Age Ione Formation has been mapped along the eastern margin of the Eastern San Joaquin Subbasin and, as described by Loyd (1983), contains interbedded kaolinitic clay, quartz sand, sandy clay, and lignite. The Ione Formation is characteristically light in color, with color influenced by iron oxide, lignite, and carbonaceous mud rocks and shale (Creely & Force, 2007). Pask and Turner (1952) subdivided the Ione Formation into upper and lower members based on mineralogy. The upper and lower members contain kaolinite (anauxite) clays. Deposits can include coarse-grained sand (up to 2 mm diameter).

Ione sand is one of the most important sources of commercial clay and silica sand in the Ione Formation (Creely & Force, 2007). Ione sand has a white color with a pearly luster and appears massive; however, closer examination usually reveals cross stratification, heavy mineral laminae, and burrows (Creely & Force, 2007). Quartz is abundant with varying feldspar content in both members.

The lower member contains 8 to 10 percent feldspar, with the upper member containing 20 to 25 percent feldspar. The minerals biotite and chlorite are rare in the lower member and common in the upper member. Heavy mineral deposits vary. The lower member contains mature minerals like zircon and ilmenite. The upper member contains hornblende and epidote. Chromite is also commonly found in the Ione Formation. The upper member is largely absent north of Jackson Valley due to erosion and deposition during the development of the overlying Valley Springs Formation. The Ione Formation is deposited in both marine and fluvial continental environments (Creely & Force, 2007).

2.1.5.1.3 Valley Springs Formation
The Oligocene-Age Valley Springs Formation is described by Loyd (1983) as stream channel and alluvial deposits derived mainly from rhyolitic volcanic rocks, including some white, welded tuffs, and ash flows. The basal contact of the Valley Springs Formation is characterized, locally, by the presence of rhyolitic conglomerate. These tuffs may display alteration to clays, and, in extreme cases, only a claystone bed with relict tuffaceous texture remains. Pure deposits of rhyolitic ash exist in areas, while many sand and ash beds are present. In general, the clay beds of the Valley Springs Formation are greenish in color, may contain silt, sand, and large pumice fragments. The sandstones range in grain-size from fine to coarse and are typically well cemented. Predominantly composed of quartz and preCretaceous material, the relatively sparse conglomerate lenses within the tuff, clay, and sandstone may also contain pumice fragments. In general, the Valley Springs Formation is predominantly fine-grained, containing less coarsegrained deposits. In the Central Valley, the Valley Springs Formation is considered to be largely non-water-bearing.

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2.1.5.1.4 Mehrten Formation
Overlying the Valley Springs Formation is the Miocene Age Mehrten Formation, described as being stream channel, alluvial, and mudflow deposits derived mainly from andesitic volcanic rocks. The Mehrten Formation is considered the oldest significant fresh water-bearing formation within the Eastern San Joaquin Subbasin.

Bartow (1992) generally describes the Mehrten in the east-central portion of the Central Valley as being sandstone composed of amphiboles, pyroxenes, and pebbles (mostly volcanic) with lenticular bedding and gray to blue color.

Bartow discusses a major change in regional volcanism as the rhyolitic pyroclastic deposits of the Late Oligocene and earliest Miocene were replaced near the end of the Early Miocene by reestablished andesitic arc volcanism in the northern Sierra Nevada. This andesitic volcanism provided the source materials for the Mehrten Formation.

Ferriz (2001) discusses how the Mehrten Formation outcrops discontinuously along the eastern flank of the Valley and was laid down in the Mokelumne area by streams carrying andesitic debris from the Sierra Nevada. The Mehrten thickens in the northeastern part of the San Joaquin Valley; generally, it can be more than 700 to 1,200 feet thick at depths ranging from more than 300 feet below ground on the east side of the valley to depths exceeding 1,400 feet along the central portion of the valley. The contact between the Mehrten Formation and underlying Valley Springs Formation is a non-distinct unconformity.

The Mehrten Formation is subdivided into upper and lower units. The upper unit contains finer grained deposits (black sands interbedded with brown-to-blue clay), and the lower unit consists of dense tuff breccia. Deep wells in the Stockton area indicate that the upper portion of the Mehrten Formation contains a high percentage of clay, suggesting that the upper portion of the unit may be finer grained than the middle or lower portions with resulting semi-confined conditions (CA DWR, 1967).

The black sands of the Mehrten Formation (black andesite detrital grains) generally have moderate to high permeability and yield large quantities of fresh water to wells, which makes them a preferred exploration target for groundwater supply in the eastern half of the Central Valley (Davis & Hall, 1959; CA DWR, 1967). East of Jack Tone Road, a large number of wells produce water from the relatively permeable “black sands” commonly described as hard sandstones (CA DWR, 1967).

2.1.5.1.5 Laguna Formation
The Pliocene to Pleistocene Laguna Formation is composed of discontinuous lenses of unconsolidated to semiconsolidated alluvial sands, gravels, and silts and is typically light brown. These poorly exposed stream-laid alluvial deposits form high terraces and are associated with the last major uplift in the Sierra Nevada.

The Laguna Formation outcrops in the northeastern part of San Joaquin County and dips at 90 feet per mile and reaches a maximum thickness of 1,000 feet, with the thickest areas (400 to 1000 feet) observed near the Mokelumne River in the Stockton Area (CA DWR, 1967). The Laguna Formation is moderately permeable with some reportedly highly permeable coarse-grained fresh water-bearing zones.

2.1.5.1.6 Turlock Lake Formation
The Turlock Lake Formation consists primarily of arkosic alluvium, mostly fine sand, silt, and in places clay, at the base grading upward into coarse sand and occasional coarse pebbly sand or gravel (Marchand & Allwardt, 1981). The age of the Turlock Lake Formation is about 600,000 to greater than 730,000 years old, but younger than about 1 million years. The Turlock Lake commonly stands topographically above the younger fans and terraces throughout the northeastern San Joaquin Valley, in a broad band between the Merhten, Laguna, and the younger Riverbank and Modesto alluvial fans to the west. A buried soil separates the Turlock Lake Formation into two units (upper and lower) in the northeastern San Joaquin Valley. The thickness of the Turlock Lake is variable and appears to increase toward the east. Estimates of thickness in the subbasins to the south range from 295 to 850 feet for eastern Stanislaus County, 1,000 feet for northern Merced County, and 160 to 720 feet in the Chowchilla area.

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The Turlock Lake Formation is differentiated from the west to east by its Corcoran Clay member that is present in the southwest corner of the Subbasin near Manteca, and dominates the area west of Highway 99 south of the Eastern San Joaquin Subbasin. The Corcoran Clay becomes interbedded with the sands and silt of the upper Turlock Lake Formation and is not found in the central and northern portions of the Subbasin. The Corcoran Clay is found ranging in thickness from a feather edge to 160 feet beneath the present bed of Tulare Lake. The Turlock Lake Formation is dominant within the basins to the south.

2.1.5.1.7 Riverbank Formation
The Riverbank Formation consists primarily of arkosic sediment derived mainly from the interior Sierra Nevada, which forms at least three sets of terraces and coalescing alluvial fans along the eastern San Joaquin Valley (Marchand & Allwardt, 1981). The Riverbank Formation is about 130,000 to 450,000 years old. The Riverbank, as exposed in the northeastern San Joaquin Valley, is primarily sand, containing some scattered pebbles, gravel lenses, and some interbedded fine sand and silt. The Riverbank unconformably overlies the Laguna Formation, and its terraces and fans truncate or are cut into Turlock Lake alluvium or fill post-Turlock Lake gullies and ravines, which, in turn, are cut and filled near the foothills by terraces of the lower member of the Modesto Formation. The Riverbank Formation is informally subdivided into three units (lower, middle, and upper) which appear to coarsen upward, like those of the older Turlock Lake Formation. The Riverbank Formation also shows a variable thickness that tends to increase toward the major river channels; 150 to 200 feet is reported in northern Merced and eastern Stanislaus Counties, 260 feet along the Merced River, and about 65 feet along the Chowchilla River.

2.1.5.1.8 Modesto Formation
The Modesto Formation is composed of mainstream arkosic sediments and associated deposits of local derivation laid down during the last major series of aggradation events in the eastern San Joaquin Valley (Marchand & Allwardt, 1981). Gravel, sand, and silt were deposited as a series of coalescing alluvial fans extending continuously from the Kern River drainage on the south to the Sacramento River tributaries in the north. They occur in a wide band immediately east of the San Joaquin Valley axis and to the west of the Riverbank and older fan remnants. Radiocarbon dating estimates the age of the Modesto Formation to be older than 9,000 years before present (B.P.) to 42,000 years B.P. Most of the prime agricultural land and many of the major cities are located in the young alluvial soils associated with the undissected Modesto terrace and fan surfaces. Modesto deposits overlie late Riverbank alluvium and older units and are locally incised or covered along modern channels by post-Modesto deposits.

The materials of the Modesto Formation are virtually identical to those of the Laguna, Turlock Lake, and Riverbank Formations, but their association with low terraces and young fans and their moderate to slight degree of erosional modification and soil profile development clearly differentiate them from older alluvium. The total thickness of the Modesto deposits is reported to be 50 to 100 feet in eastern Stanislaus County, 130 feet along the Merced River, and about 65 feet along the Chowchilla River fan. The Modesto Formation also thickens toward each river channel and toward the south; there is significant evidence of local facies changes laterally. Exposed sections differ substantially from exposures near the foothills and from exposures along the westward draining rivers.

2.1.5.1.9 Post-Modesto Deposits – Recent Alluvium and Basin Deposits In general, these younger units are less consolidated and sedimentary in nature, representing a sequence of young alluvial fills including alluvial fans, channel, point bar, levee, crevasse splay, interdistributary, and floodbasin alluvium.

The alluvial fan deposits are much smaller than the late Modesto fans. The age of these deposits ranges from 9,000 years B.P to modern time. Lacustrine, swamp, and marsh deposits are presently accumulating in poorly drained areas on the alluvial fan toes. In oxbow lakes on river flood plains, near the edge of the Delta where Holocene sea level rise caused alluviation of the lower Mokelumne and Cosumnes Rivers, lakes and swamps have formed where tributary gullies have been blocked by mainstream aggradation (Marchand and Allwardt, 1981).

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2.1.6 Faults and Structural Features
The Stockton Fault – The Stockton Fault is the largest fault in the Eastern San Joaquin Subbasin, shown in Figure 2-19. It is a large reverse fault with displacements of up to 3,600 feet (1,100 m) that trends transverse to the regional structure and bounds the Stockton Arch on the north. Bartow (1985) shows relative movement along the fault as northside-down. The timing of the vertical movement is predominantly post-Eocene (Hoffman, 1964), and the latest movements appear to have been subsequent to deposition of the basal part of the Valley Springs Formation, probably during Miocene time.

The Vernalis Fault – The Vernalis Fault is a reverse fault with northwest-southeast trend that bounds the TracyVernalis anticlinal trend that is mapped outside of the west boundary of the Eastern San Joaquin Subbasin. East-sidedown movement of as much as 1,500 feet (460 m) probably took place at the same time as the major movements on the Stockton Fault (Bartow, 1985). The relative thickness of sediments can be inferred from the elevations of the base of the freshwater aquifer system shown in Figure 2-20. The freshwater aquifer system on the north side of the Stockton Fault extends approximately 600 feet deeper than the aquifer system south of the fault. Relative movement along the fault is north-side-down, thus allowing for greater accumulation of the continental Tertiary sediments and deepening of the aquifer materials in this area.

Stockton Arch – The Stockton Arch is a broad transverse structure that underlies the southern half of the Eastern San Joaquin Subbasin. The arch is bounded on the north by the Stockton Fault, and the southern limit is the line of truncation of Paleogene strata south of Modesto (Bartow, 1985). Indications of northward-shallowing marine facies in the lower Paleogene sequence suggests that the arch was present by Paleocene time. Erosion during the Oligocene time apparently reduced whatever physiographic expression the arch may have had and left a nearly flat plain prior to deposition of the later Tertiary units.

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Figure 2-19: Faults and Structural Features
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As a result of the north-side-down movement along the Stockton Fault, the Tertiary sediments are thicker north of the fault and thinner south of the fault. This feature also influences the location, depth, and thickness of the “base of the fresh water,” as shown below in Figure 2-20. The base of fresh water is discussed further in Sections 2.1.7 and 2.1.8.2.

Figure 2-20: Base of Fresh Water Elevation and Stockton Fault Angular unconformities – There are a series of angular unconformities formed during the Cenozoic-related to uplift of the Sierra Nevada to the east (Bartow, 1985). The Cenozoic history of the Sierra Nevada is one of progressive westward tilting, perhaps episodic, with an increasing rate in the late Cenozoic. The subtle angular unconformities that separate the Tertiary units are evidence of this progressive tilting. The Tertiary units rarely have dips of more than 2 degrees; the difference in dip between the Ione and the Valley Springs Formations, for example, may be less than 1 degree. The discordances are most apparent in terms of gradients of depositional surfaces measured in distances of several miles. The largest discordances are between the Ione Formation (about 1,500 feet/mile) and the Valley Springs Formation (94 - 120 feet/mile), between the Mehrten Formation (99 - 131 feet/mile) and the Laguna Formation (52 - 79 feet/mile), and between the Laguna Formation and the Quaternary deposits (less than 18 feet/mile). The Ione-Valley Springs unconformity represents the Oligocene regression that affected most of central and southern California, and the Mehrten-Laguna unconformity probably marks the accelerated uplift of the Sierra Nevada beginning 3 to 5 million years ago (Huber, 1981) in the central part of the range. The Sierra Nevada was relatively stable through the Miocene with only a minor discordance between the Valley Springs and Mehrten Formations; their lithological difference reflects primarily a change from rhyolitic to andesitic volcanism in the source area. Uplift of the Sierra Nevada continued through the Quaternary, but the record is complicated by Quaternary climatic events (e.g., glaciation) which were the principal controlling factor in Quaternary sedimentation for the east side of the Great Valley.

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2.1.7 Geologic Cross-Sections
Five geologic cross-sections (A-A’, B-B’, C-C’, D-D’, and E-E’) were developed for the Eastern San Joaquin Subbasin based on the stratigraphic information amassed as part of the data compilation efforts. A geologic cross-section is an interpretive diagram of the lateral and vertical subsurface relationships of geologic formations. A cross-section location map with locations of groundwater and oil and gas wells reviewed in the development process is provided as Figure 2-21. Three of the cross-sections (A-A’ through C-C’) are along east-west transects in the north, central, and southern portion of the Subbasin, respectively; two of the cross-sections (D-D’ and E-E’) are generally along north-south transects. Cross-section D-D’ generally transects the cities of Lodi, Stockton, and Manteca in the west portion of the Subbasin, and cross-section E-E’ transects the Eastern San Joaquin Subbasin along the alignment of Jack Tone Road from the northeast to the southwest portion of the Subbasin. Each of the five geologic cross-sections are provided in Figure 2-22, Figure 2-23, and Figure 2-24.

Four additional cross-sections (F-F’, G-G’, H-H’, and I-I’) were added as part of the 2024 Amended GSP, following the release of DWR’s AEM data. To supplement the existing cross-sections by geologic formation, these additional crosssections show an estimate of percent coarseness of the subsurface material. Percent coarseness estimations were developed by DWR, derived from AEM resistivity data through a comprehensive translation process in which texture characteristics of the subsurface are related to the collected resistivity measurements. Cross-sections by coarse fraction represent multiple flown survey lines stitched together to show a continuous line. Darker brown areas represent relatively finer materials (lower coarse fraction) and lighter yellow areas represent coarser materials (higher coarse fraction). Lithology logs used by DWR to generate the texture interpretation of the resistivity data are included on each cross-section. Figure 2-25 shows the locations of these four additional cross-sections. Cross-sections F-F’, G-G’, HH’, and I-I’ are included in Figure 2-26, Figure 2-27, Figure 2-28, Figure 2-29, respectively.

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Figure 2-21: Cross-Section, by Formation, Location Map
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Figure 2-22: Hydrogeologic Cross-sections A-A’ and B-B’ EXHIBIT 1
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Figure 2-23: Hydrogeologic Cross-sections C-C’ and D-D’ EXHIBIT 1
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Figure 2-24: Hydrogeologic Cross- section E-E’
SOUTH
E’
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Figure 2-25: Cross-Section, by Percent Coarseness, Location Map EXHIBIT 1
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Figure 2-26: Percent Coarse Cross-Section F-F’
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Figure 2-27: Percent Coarse Cross-Section G-G’
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Figure 2-28: Percent Coarse Cross-Section H-H’
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Figure 2-29: Percent Coarse Cross-section I-I’
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Stratigraphic data fromwell completion reports of hundreds of water wells and oil and gas wells (indicated by an asterisk on the cross-sections) were used to develop the geologic cross-sections. Stratigraphy (e.g., clays and silts, sands and gravels, sedimentary rock, metamorphic and igneous rock) is presented directly on the cross-sections along with the well screen interval (shown in red). The deeper oil and gas wells are shown extending to the bottom depth of the crosssections, but many extend several hundred to thousands of feet beyond the depictions provided.

The analysis interpreted geologic formations from the borehole data after digitizing stratigraphic data from the various well log sources. This process relied heavily on the distinguishing features of each formation. Particularly, the black sands prevalent in the Mehrten Formation and evidence of shells noted in the descriptions that likely indicated a change to marine sediments of the Ione Formation were often mentioned in well logs. The analysis used surficial geology, location, and depth of the borehole to determine geologic formations. The analysis inferred formation contacts in places where data were limited, including areas on the east and west limbs of the cross-sections, as well as vertically throughout.

As evident on the east-west geologic cross-section transects, the oldest formations are present on the east side of the Eastern San Joaquin Subbasin, shown overlapping the older sedimentary and/or basement rocks of the Sierra Nevada (A-A’), with progressively younger formations present to the west and vertically occupying shallower depth intervals.

The east-west depictions also show the contacts of the formations steeply dipping in the east and nearly flat lying or at low gradients to the west. The northwest-southeast trending cross-section D-D’ shows the formations in their relatively flat-lying positions, with oldest formations on the bottom and progressively younger formations above. This crosssection transect is essentially normal to the dip of the beds. In slight contrast to D-D’, the transect of cross-section E-E’ is somewhat oblique to the dip of the beds, thus there is an apparent down-dip toward the south. This effect is seen because the transect is moving into younger materials from the south toward the north.

The base of fresh water is superimposed on the cross-sections as supported by works from Page (1974) and Williamson (1989), as represented in Figure 2-20. The base of the fresh water represents the vertical extent of fresh non-saline groundwater within the Eastern San Joaquin Subbasin principal aquifer. The sands of the Mehrten Formation are thickest in the northeast portion of the basin and there is a corresponding deepening of the freshwater aquifer on the north side of the Stockton Fault, as shown on cross-sections A-A’ and B-B’. The depth of the base of fresh water is shallower south of the Stockton Fault in the southern portion of the Eastern San Joaquin Subbasin.

Further discussion of the principal aquifer is provided in Section 2.1.9.

Well depths generally decrease in total depth from north to south across the Subbasin and locally within proximity of the major surface water drainages. In general, coarser sands are found at shallower depths within the lower unit of the Laguna Formation and upper Mehrten Formation (C-C’) in the area of the Stanislaus River Drainage. Similarly, shallow well completions evident on cross-section D-D’ and the southern portion of E-E’ are indicative of the sandier nature of the recent alluvial deposits, the Turlock Lake Formation, and the Laguna Formation near the San Joaquin River.

2.1.8 Basin Boundaries

2.1.8.1 Lateral Boundaries and Boundaries with Neighboring Subbasins The Eastern San Joaquin Subbasin is within the larger San Joaquin Valley, which comprises the southernmost portion of the Great Valley Geomorphic Province of California. Groundwater subbasins bounding the Eastern San Joaquin Subbasin are shown in Figure 1-5 and include:
• Cosumnes Subbasin to the north of Dry Creek
• Modesto Subbasin to the south of the Stanislaus River • South American Subbasin to the northwest of the Mokelumne River • Solano Subbasin to the northwest of the Mokelumne River EXHIBIT 1
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• East Contra Costa Subbasin to the west of the San Joaquin River • Tracy Subbasin to the west of the San Joaquin River
Foothill and bedrock highs are to the east within Calaveras and Amador Counties.

2.1.8.2 Definable Bottom of the Basin
The base of the fresh water defines the bottom of the basin, the maximum vertical extent of fresh non-saline groundwater within the Eastern San Joaquin Subbasin. While water-bearing materials exist below this depth, the saline nature of the groundwater, in addition to the depth itself, generally makes accessing deeper groundwater not economically viable.

Because of the extreme depths to the base of fresh water shown in Figure 2-20, efforts by the USGS have been used to define the “base of fresh water” through the interpretation of the California DOGGR well logs and deep oil well geophysical logs as depicted on maps and cross-sections above. Base of fresh water (encountered saline) has been observed as shallow as 650 feet below ground surface (bgs) in the eastern part of the basin to over 2,000 feet bgs in the northern part of the basin as depicted on the surface contour map and supported by work completed by Williamson (1989).

2.1.9 Principal Aquifer
The Eastern San Joaquin Subbasin HCM has one principal aquifer that provides water for domestic, irrigation, and municipal water supply and that is composed of three water production zones. The zones have favorable aquifer characteristics that deliver a reliable water resource because of their basin location and sand thickness.

The zones are:
• Shallow Zone that consists of the alluvial sands and gravels of the Modesto, Riverbank, and Upper Turlock Lake Formations
• Intermediate Zone that consists of the Lower Turlock Lake and Laguna Formations • Deep Zone that consists of the consolidated sands and gravels of the Mehrten Formation Details on the formations are provided in Section 2.1.5.

2.1.9.1 Zones within Principal Aquifer
Zones within the principal aquifer are based on the compilation of five hydrogeologic cross-sections (see Figure 2-22 through Figure 2-24). Cross-sections were based on over 330 well logs in the Subbasin. From these data, well depths for municipal and irrigation wells range from 75 to over 800 feet bgs, with an average depth of 350 feet bgs.

Well logs were reviewed for the following information used in preparing the cross-sections:
• Depth of water table
• Depth and thickness of saturated fine to coarse grained sand and gravel layers • Depth and thickness of discrete layers of sands
• Depth and thickness of discrete clay or silt layers that locally confine groundwater • Depth of water-bearing aquifer materials (e.g., sands and gravels) down to the base of fresh water and deeper, where available
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Analyses identified significant permeable zones with high production rates and good water quality at relatively shallow depths (less than 700 feet bgs) due to the following conditions:
• The relatively shallow depths of production wells had high specific capacity that met the water supply demand and reduced the cost associated with drilling deeper • The base of fresh groundwater is deep; ranging from depths of 700 to 1,900 feet bgs • Deeper water is saline and not considered suitable for potable or agricultural use These results were cross-checked with the AEM data to validate the texture of shallow deposits, such as alluvial fans and sediments that interact with streams, and were used in updates to the hydrogeological conceptual model and the ESJWRM model stratigraphy. See Appendix 2-C for more detail on how AEM texture data were incorporated into the representation of Subbasin hydrostratigraphy.

Figure 2-30 and Figure 2-31 depict the wells used during this hydrogeologic characterization effort. Information compiled was used to detail the three permeable water-bearing zones described from surface downward in the following sections.

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Figure 2-30: Bottom Elevation of Water-Bearing Zones (Shallow) EXHIBIT 1
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Figure 2-31: Bottom Elevation of Water-Bearing Zones (Deep and Intermediate)

2.1.9.1.1 Shallow Zone
The shallow water-bearing zone is composed of permeable sediments from recent alluvium, Modesto/Riverbank Formations, and the upper unit of the Turlock Lake Formation that are present west of the older geologic formations and extend across the majority of the Eastern San Joaquin Subbasin. This zone is generally unconfined above the aquitards (clays/silts, including Corcoran clay, and old soil horizons/hardpan layers).

The depositional structure on the eastern side of the valley trough is depicted on the hydrogeologic cross-sections A-A’ through E-E’ (see Figure 2-22, Figure 2-23, and Figure 2-24). This structure results in the groundwater flow that follows both the dip of the beds and hydraulic head differentials. Erosional and depositional features dominate aquifer characteristics. The cross-sections also depict the aquifer thickness from 30 feet to greater than 300 feet.

The Shallow Zone characteristics are supported by the sand thickness information detailed below along with review of basin aquifer parameters and AEM texture data. This zone has high yielding wells. Aquifer characteristic values range as follows (CA DWR, 1967; Burow et al., 2004):
• Transmissivities up to 90,000 gpd/feet
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• Specific yields up to 17 percent
• Vertical permeability estimates up to 0.1 feet/day

2.1.9.1.2 Intermediate Zone
As depicted on the hydrogeologic cross-sections A-A’ through E-E’ (see Figure 2-22, Figure 2-23, and Figure 2-24), sands, typically from 10 to over 60 feet thick, are found below the low permeable clay layers or aquitards. The sands and gravels are developed with one relatively continuous sand unit at 350 feet bgs, within the top of the lower unit of the Turlock Lake Formation and Laguna Formation, thinning out at topographic highs to the east. Eastern basin depositional structure shows a pinching, wedging, and combination water-bearing zones with the surficial alluvium.

The aquifer characteristics are supported by the sand thickness information detailed herein for the principal aquifer.

The eastern distribution of this water-bearing zone near the surface suggests unconfined groundwater conditions.

Typically, this zone is found under semi-confined conditions with high yielding wells and is considered the current primary production zone. Area groundwater numerical models support the CA DWR (1967) and Burow and others (2004) aquifer characteristic values range as follows:
• Transmissivities up to 59,500 gallons per day (gpd)/feet • Storage coefficients typically 0.00001 (unitless)
• Vertical permeability estimates up to of 0.07 feet/day

2.1.9.1.3 Deep Zone
The water-bearing “black sands” of the semi-consolidated Mehrten Formation are considered a significant source of water for Eastern San Joaquin Subbasin production wells. The formation is thick in the west, with a limited number of deep wells that penetrate the entire depth of this unit as depicted on the hydrogeologic cross-sections A-A’ through E-E’ (see Figure 2-22, Figure 2-23, and Figure 2-24). This water-bearing zone is confined due to the thick overlying clay units, consolidation, and basin location. Semi-confined conditions are more likely to the east because of the dipping of beds and stratigraphic layer thinning and erosion of clay/silt beds. The beds of the Mehrten Formation dip are at a steeper slope of 90 to 180 feet per mile westward. Consolidated sediments of the Mehrten and Valley Springs Formations are at valley bottom depth and exposed on the eastern foothills. Recharge to these aquifer formations occurs because of the high topographic setting with increased rainfall and exposure of weathered surface and runoff from the adjacent fractured Sierran bedrock.

As depicted on the hydrogeologic cross-sections A-A’ through E-E’ (see Figure 2-22, Figure 2-23, and Figure 2-24), boring logs indicate a significant 30-foot thick gravel encountered at a depth from 140 to 170 feet. Thickly bedded sands were found to exceed 250 feet. At the eastern margins of the basin, consolidated portions of the Mehrten, Valley Spring, and Ione Formations are important for low-yielding bedrock wells and are considered aquifer recharge sources for the Eastern San Joaquin Subbasin. The relatively low permeability and consolidated nature of the Valley Springs and Ione Formations act as the bottom of the Deep Zone (Burow et al., 2004).

The aquifer characteristics are supported by the sand thickness information. The well yields are high in this zone, over 1,000 gallons per minute (gpm). Area groundwater numerical models support the CA DWR (1967) and Burow and others (2004) aquifer characteristic values range as follows:
• Transmissivities up to 250,000 gpd/feet
• Storage coefficients that are typically 0.0001
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2.1.9.1.4 Limited Aquitards
The Corcoran Clay member of the Turlock Lake Formation and other interbedded clay/silts are aquitards that inhibit groundwater flow. The Corcoran Clay (found at the base of the upper unit of the Turlock Formation) is present at a depth of about 200 feet bgs. The Corcoran Clay has a limited distribution in the extreme southwestern extent of the Subbasin, southwest of the City of Manteca. The clay is typically 20 to over 100 feet thick and is locally eroded and interfingered with coarser materials at its margin. Groundwater below the Corcoran Clay is confined. The Corcoran Clay is found more significantly in subbasins to the south where it is a significant vertical barrier to flow.

Thick clay and silt layers are found within the Laguna and Mehrten Formations. These two formations each have two documented upward coarsening alluvial sequences (Burow et al., 2004). Significant clay and paleosols divide the water-bearing zones at the base of each sequence. The cross-sections (Figure 2-22, Figure 2-23, and Figure 2-24) show both the clay and silt horizons range in thickness from less than 10 feet to over 150 feet. The vertical permeability estimates range from 0.01 to 0.007 feet per day (Burow et al., 2004).

Discontinuous clay horizons have been eroded significantly by the movement of the ancestral rivers. As depicted on the cross-sections, thickest sequences of uppermost permeable units and overbank fines below these layers have been observed. The general thickness and depth are supported by a southeast to northwest movement of river channels to the existing channel location.

Hydraulic connection for the entire depth of the principal aquifer is supported by cross-section depictions that indicate the laterally extensive interbeds of high and low permeable layered deposits. The historical erosional and depositional history supports the referenced hydraulic interconnection. This observation is consistent with the possible thinning and wedging out of the regional clay units due to reworking or ancestral erosion (Davis et al., 1959). In addition to the natural connectivity, the number of water wells drilled through these zones also indicates additional hydraulic connection because of the construction of long well gravel packs that connect the water-bearing zones.

2.1.9.1.5 Deep Saline Groundwater
Connate or saline water occurs from the base of fresh water (shown in Figure 2-20 or Figure 2-31) to the base of continental deposits (shown in Figure 2-32), forming a saline layer that ranges in thickness from 50 to 2,250 feet from the east to the west across the Subbasin. The deep saline layer is not currently a water production zone for consumption or land application. Information used in developing the thickness of the saline water above continental deposits is from Page’s 1974 Base and Thickness of the Post Eocene Continental Deposits in the Sacramento Valley and the thickness of the aquifer developed by Williamson and others (1989).

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Figure 2-32: Elevation of Base of Continental Deposits
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2.1.9.2 Aquifer Characteristics and Groundwater Quality Because of the horizontal and vertical distribution of sediments and hydraulic connection between the water-bearing zones, one Principal Aquifer is defined.

An important step in aquifer characterization includes the completion of sand and gravel thickness (isopach) maps. An isopach map illustrates thickness variations within a tabular layer or stratum. Isopachs are contour lines of equal thickness over an area. The combined isopach map for the principal aquifer is depicted on Figure 2-33. The isopach map details are as follows:
• Over 313 water supply well logs with depths to 1,000 feet were used, with an average depth of 540 feet bgs. • Average sand and gravel thickness is 140 feet.
• The thickest sand and gravel sequences ranged from 500 to 700 feet near the Stanislaus River, south of Woodward Reservoir and northeast of Oakdale.
• Thicknesses from 200 to 400 feet were observed west of Morada along Bear Creek and toward the Delta. • The 200 to 500 feet thickness contours were observed near Stockton along the Duck Creek historical drainage.

Recognizing the sand and gravel thickness and the relative hydraulic conductivity of these permeable units, a more comprehensive understanding of the aquifer transmissivity can be made as detailed in Section 2.1.9.2.1.

As discussed in Section 2.1.4.3, soils facilitate rainfall and applied water infiltration, which is a significant recharge source for the Shallow Zone. Other recharge takes place through infiltration and percolation of surface water bodies and via groundwater flow from upgradient areas to the zones within the entire principal aquifer and potentially from flow between subbasins from the north, south, and west. The Intermediate and Deep Zones are recharged via infiltration near sand and gravel layers that are typically thicker near historical riverbeds. Vertical movement of water through sand deposits is more rapid compared to the confining clay deposits. In the high topographic areas along the east margin of the Subbasin, water-bearing zone sediments are exposed at the surface and considered significant to recharge.

2.1.9.2.1 Aquifer Parameters and Production Zone Well Capacities The GSP uses several sources to summarize the field-tested aquifer characteristics and production zone well capacity information for the principal aquifer.

For depiction purposes, Table 2-3 includes four investigation areas encompassing the entire Subbasin: Calaveras County, Farmington, Manteca, and near the Stanislaus Triangle Area (Riverbank). For these examples, the maximum well yields range from greater than 100 to 2,800 gpm. The range in specific capacity is 27 to 90 gpm/ft of drawdown.

These numbers relate to the testing of individual well capacities and the anticipated pumping water level related to the pumping rate. Transmissivity and storage values relate to the aquifer character anticipated at a distance away from a pumping well. Specific yield (SY) is defined as a unit volume of water released from an aquifer per unit decline in water table. Specific storage (SS) of a saturated aquifer is defined as the amount of water released from storage per unit decline in hydraulic head (Freeze and Cherry, 1979).

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Figure 2-33: Sand and Gravel Isopach Map
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Table 2-3: Production Zone Capacities
Sources/Well
Information
Maximum
Well
Yield
(gpm)
Maximum
Well
Specific
Capacity
(gpm/ft
drawdown)
Maximum
Transmissivity
(gpd/ft)
Maximum
Specific
Yield
(Unconfined
[%])
Specific
Storage
(Confined
[Unitless])
Sand and
Gravel
Thickness
Encountered
Mehrten
Depth, (feet)
Entire Eastern
San Joaquin
Subbasin
(CA DWR, 2006)
1,500 n/a n/a 7.3 % >150 400-600
Calaveras County
(WRIME, 2003)
>100 >10 >35,000 >6 % >120 At Surface
Farmington
(DE, 2012)
800 27 19,600 >5 % 0.001 >110 230
Manteca
(NV5, 2017)
2,500 90 61,000 >10 % 0.0001 >130 350
Stanislaus
Triangle
(BookmanEdmonston, 2005)
>2,800 >40
(DE, 2007)
35,000 17 % 0.001 >150 Dip to the
West
Using the basic physical properties of groundwater flow, a confined aquifer transmissivity is defined by:

T = Kb
Where: T is transmissivity
K is the hydraulic conductivity (rate of flow under a unit hydraulic gradient through a unit cross-sectional area)
b is the aquifer thickness.

Using a typical clean sand hydraulic conductivity value of 500 gpd/feet 2 and a thickness of 120 feet, the aquifer
transmissivity averages approximately 60,000 gpd/feet, which is similar to the documented values reported above (Freeze and Cherry, 1979). For additional comparison, data for the five layers of the ESJWRM were provided in the ESJWRM Model Report and Version 3.0 Model Documentation Updates TM (see Appendix 2-A and Appendix 2-C, respectively)
The distribution of production wells and monitoring wells is provided on Figure 2-30 and Figure 2-31. Table 2-4 provides descriptors for the three water-bearing zones:
• Number of wells for each zone
• Well depths
• Wells used on the cross-sections
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Additional aquifer parameter confirmation is provided by the ESJWRM as follows (Woodard & Curran):
• Horizontal Hydraulic Conductivity – The horizontal hydraulic conductivity varies across the non-saline model layers ranging from 1.1 ft/day to 72.7 feet/day or 0.148 to 10 gal/day/feet2. • Specific Storage and Yield – SS and SY are used to represent the available storage at nodes in confined and unconfined aquifers. SS values range from 4.18 x 10-6to 2.05 x 10-4. SY values range from 4 to 10 percent.

Table 2-4: Wells within Water-Bearing Zones
All Wells
Water-Bearing Zone Number of
Wells
Average Construction
Depth (feet bgs)
Average Construction Bottom
Elevation (feet MSL)
Shallow 452 165 -82
Intermediate and Deep 201 539 -411
Pumping Wells
Water-Bearing Zone Number of
Wells
Average Bottom of
Screen Depth (feet bgs)
Average Bottom of Screen
Elevation (feet MSL)
Shallow 148 270 -238
Intermediate and Deep 113 369 -300
Groundwater Wells Used in Cross-Sections, by Formation
Water-Bearing Zone Number of
Wells
Average Bottom of
Borehole Depth (feet
bgs)
Average Bottom of Borehole
Elevation (feet MSL)
Shallow 39 234 -144
Intermediate and Deep 273 672 -566
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2.1.9.2.2 Regional Historical Groundwater Flow and Surface Water Interaction The horizontal groundwater flow direction for the Eastern San Joaquin Subbasin is typically towards areas of lower groundwater near the center of the Subbasin. The flow generally mirrors topography and is relatively consistent over time. The flow direction follows the overall west dipping gradient of the geologic formations in the eastern portions of the Subbasin. Higher groundwater elevations are in the foothills on the east side of the Subbasin, and the elevations decrease following the topography. In the western portion of the Subbasin, groundwater flows east toward areas with relatively lower groundwater elevation. Horizontal groundwater flow is further discussed in Section 2.2.

The GSP evaluates vertical groundwater gradients using the USGS nested wells in the Eastern San Joaquin Subbasin.

Clark and others (2012) drilled and assessed several nested wells or multiple well sites in the Eastern San Joaquin Subbasin. These nested well sites include three to five monitoring wells per borehole with screen intervals at depths of approximately 100 to 900 feet (Clark et al., 2012). Groundwater elevation in these monitoring wells, measured from 2006 to 2008, usually indicate the same trend. Groundwater elevation is typically lower in monitoring wells with deeper screen placement, suggesting a downward flow of groundwater. The difference in groundwater elevations from the shallowest to deepest monitoring wells within each borehole is typically between 5 and 20 feet (Clark et al., 2012).

Additional discussion regarding differences and distribution across the Subbasin is provided in Section 2.2.

Historical groundwater-surface water interaction in the context of the twenty-seven years of the historical model (ESJWRM) is discussed in Section 2.2.6.

2.1.9.2.3 General Groundwater Quality

2.1.9.2.3.1 Geologic Formation Groundwater Quality
The USGS and other government agencies completed several major studies concerning groundwater quality in the Central Valley of California, which includes the Eastern San Joaquin Subbasin. Repeatedly mentioned in these studies is the natural geochemical effects on groundwater quality that is specific to geologic formations (Creely & Force, 2007; Faunt, 2009; CA DWR, 1967). This natural effect is of great interest for the GSP implementation because groundwater level fluctuations from overdraft and recharge may result in water quality changes that is specific to geologic formations.

Natural geochemical reactions can be highly variable, even from well to well, as reactions depend on a number of factors, including the amount of 1) reactive surface area of the formation sediments; 2) available oxygen in the formation as affected by fluctuations in groundwater elevation, depth to groundwater, and oxygenated near-surface recharge; and 3) potentially inorganic-oxidizing bacteria.

For the Eastern San Joaquin Subbasin, igneous and metamorphic rocks of the Sierra Nevada Mountains underlie the upstream drainages. These rocks predominately contain oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium (Creely & Force, 2007). Rivers draining areas of granitic rocks typically have better water quality than metamorphic or volcanic rocks (CA DWR, 1967). For example, the Mokelumne River drains areas of granitic origin and has a lower salt content than the Calaveras River, which drains an area of primarily metamorphic rocks (CA DWR, 1967). Streams originating from either igneous or metamorphic rocks have relatively low amounts of dissolved solids, compared to marine sedimentary rocks that make up the Coast Range west of the Subbasin (Faunt, 2009). However, marine formations also underlie continental deposits in the Eastern San Joaquin Subbasin and have considerable amounts of chlorine, sulfur, bromine, and boron from connate water (Creely & Force, 2007). Connate water originates from fluids that are trapped in the pores of the sedimentary rocks as they are deposited and can contain many mineral components as ions in solution. Above these marine formations are continental deposits described in Section 2.1.5.

Groundwater quality in wells in Calaveras County is characterized by Metzger and others in a 2012 study, Test Drilling and Data Collection in the Calaveras County Portion of the Eastern San Joaquin Groundwater Subbasin, California, December 2009 – June 2011 (Metzger et al., 2012). These wells are in the eastern portion of the Eastern San Joaquin Subbasin, in an area underlain by the Ione and Valley Springs Formations. This study assessed groundwater samples EXHIBIT 1
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and identified three water types present: calcium-magnesium-bicarbonate, sodium-bicarbonate, and mixed cationmixed anion water. The mixed cation-mixed anion group consisted mostly of sodium and chloride. These groundwater samples also showed high levels of arsenic, which were attributed to pH level variation or redox potential (Metzger et al., 2012). The Ione Formation, for instance, is known to have high sulfate levels in groundwater related to the pH influence on pyrite-sulfide rich coal deposits.

Arsenic is of particular concern because it is naturally occurring in the Eastern San Joaquin Subbasin and is hazardous to human health. Izbicki and other’s (2008) study, Source, Distribution, and Management of Arsenic in Water from Wells, Eastern San Joaquin Groundwater Subbasin, California, assesses the concentration and sources of arsenic in various wells. Arsenic was detected mostly in San Joaquin County, and the largest concentrations were in the western portion of the Subbasin (Izbicki et al., 2008). The surficial geology in this area consists of the Modesto and Riverbank Formations, which are underlain by the Turlock Lake and Laguna Formations (see Figure 2-18, Figure 2-22, Figure 2-23, and Figure 2-24). Sources of arsenic include weathering of minerals containing arsenic, desorption of arsenic under certain pH values, and release of arsenic in redox conditions (Izbicki et al., 2008).

Another element of great importance is nitrogen as it is included in many compounds that are by-products of agriculture, which heavily dominates the landscape of the Eastern San Joaquin Subbasin. Elevated levels of nitrate can typically occur as a result of fertilizer application, manure and septic waste, and natural sources. Extensive work by Holloway and others (1998) showed the Mokelumne River watershed contained significant quantities of nitrogen from bedrock lithology. The upper part of the watershed, outside the Eastern San Joaquin Subbasin, is underlain by igneous and metamorphic rock, but the metasedimentary and metavolcanic rocks contained the highest levels of nitrogen (Holloway et al., 1998).

General water quality of principal aquifers is summarized in the following sections, as required by CCR Title 23 §354.14.

General water quality can be determined by assessing commonly measured inorganic parameters as indicators of change. Evaluating these inorganic parameters involves looking at historical trends and comparing results to certain thresholds, as well as determining water types. These parameters include major cations and anions, listed below:

Anions Cations
Bicarbonate Calcium
Carbonate Magnesium
Chloride Potassium
Sulfate Sodium

2.1.9.2.3.2 Ion Composition
Evaluating the historical trends of these parameters is not straightforward. GAMA records include some groundwater quality results for the Eastern San Joaquin Subbasin going back to the 1940s. However, a thorough analysis requires a large amount of data on all the major cations and anions mentioned above. A large number of measurements of this kind were taken from 2005 to 2017, as shown in Figure 2-34. This analysis was not updated as part of this GSP amendment as basic groundwater chemistry reflects the geology of origin, which has not varied considerably since the preparation of the 2020 GSP.

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Figure 2-34: Total Number of Cation/Anion Measurements in the Eastern San Joaquin Subbasin EXHIBIT 1
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General water quality of the Subbasin can be determined by assessing water type over specific years, in this case, within the time frame of 2005 to 2017. Evaluating the years 2005, 2011, and 2017 provides an even spread over the selected time frame and gives an idea of possible water type trends. Trilinear diagrams for each of these years show relative concentrations of the major cations and anions (see Figure 2-35). Each symbol in the diagram represents a water sample collected. Water samples, represented by the same symbol, are plotted in the two lower triangle diagrams for each year based on their relative cation (left) and anion (right) concentrations. The top diagram represents a projection of the two ternary diagrams for easier comparison.

Due to the difference in sampling locations, the years 2005 and 2011 show carbonate and bicarbonate-rich waters, and 2017 displays increased chloride and sulfate concentrations in some wells. These dates correlate to both data size increases and heavier rainfall periods. Chloride concentrations in 2017 are generally less than 150 milligrams per liter (mg/L), with some higher measurements reaching 2,000 mg/L. Sulfate
concentrations in 2017 are mostly under 300 mg/L, but a few extremely high levels up to 100,000 mg/L exist near the City of Manteca.

GAMA groundwater quality data in the northern portion of the San Joaquin Valley Groundwater Basin were assessed by
Bennett et al. in 2006. Groundwater samples were compared to thresholds such as the U.S. Environmental Protection Agency (USEPA) secondary maximum contaminant levels (SMCL).

None of the major cations and anions measured in the Eastern San Joaquin Subbasin resulted in exceedances of the SMCLs (Bennett et al., 2006). These measurements took place in December 2004 to February 2005. Additional parameters were sampled in this study and are discussed further in Section 2.2 (Historical Groundwater Conditions).

Figure 2-35: Trilinear Diagrams
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2.1.9.2.3.3 Total Dissolved Solids
A wide range of total dissolved solids (TDS) values exist in the Eastern San Joaquin Subbasin. Based on data in the GAMA database from 2005 to 2017, TDS values generally varied from 100 to 2,000 mg/L (Figure 2-36), with a median value of 520 mg/L. Over the 13-year period shown in Figure 2-36, the median concentration of TDS has steadily increased from approximately 400 mg/L in 2005 to approximately 600 mg/L in 2017. Figure 2-37 shows the variation of TDS concentrations across the basin in 2017. Sources of TDS in the Subbasin include Delta sediments, deep deposits, and irrigation return water, as discussed in Section 2.2.4.1. Additional details on TDS concentrations are provided in Section 2.2 (Historical Groundwater Conditions).

Figure 2-36: TDS Annual Variation
Note: This Box-and-Whisker plot represents a summary of five different statistic values of the distribution. Minimum and maximum values are represented by the end points of the extended lines. The center line indicates the median. The top and bottom of the rectangle indicate the first quartile (25th percentile) and third quartile (75th percentile) of the distribution, respectively.

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Figure 2-37: TDS Concentrations in 2017

2.1.9.2.3.4 Chloride
Chloride concentrations also vary considerably across the Eastern San Joaquin Subbasin. Based on data in the GAMA database from 2005 to 2017, chloride values generally varied from non-detect to 300 mg/L (Figure 2-38), with a median value of 50 mg/L. Over the 13-year period shown in Figure 2-38, the median concentration of chloride has remained fairly stable. Higher chloride concentrations during 2017 are apparent near the cities of Manteca and Stockton (
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Figure 2-39). Sources of chloride in the Subbasin are similar to those for TDS and include Delta sediments, deep deposits, and irrigation return water. Additional details on chloride concentrations are provided in Section 2.2 (Historical Groundwater Conditions).

Figure 2-38: Chloride Annual Variation
Note: This Box-and-Whisker plot represents a summary of five different statistic values of the distribution. Minimum and maximum values are represented by the end points of the extended lines. The center line indicates the median. The top and bottom of the rectangle indicate the first quartile (25th percentile) and third quartile (75th percentile) of the distribution, respectively.

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Figure 2-39: Chloride Concentrations in 2017

2.1.9.2.3.5 Sulfate
Sulfate concentrations vary considerably across the Eastern San Joaquin Subbasin ranging from non-detect to around 250 mg/L with a median value of around 25 mg/L Figure 2-40, based on data in the GAMA database from 2005 to 2017. Over the 13-year period shown in Figure 2-40, the median concentration of sulfate, like chloride, has remained fairly stable and does not show any obvious trends. Higher sulfate concentrations during 2017 are apparent near the cities of Manteca and Stockton Figure 2-41
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Figure 2-40: Sulfate Annual Variation
Note: This Box-and-Whisker plot represents a summary of five different statistic values of the distribution. Minimum and maximum values are represented by the end points of the extended lines. The center line indicates the median. The top and bottom of the rectangle indicate the first quartile (25th percentile) and third quartile (75th percentile) of the distribution, respectively.

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Figure 2-41: Sulfate Concentrations in 2017
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2.1.10 HCM Data Gaps
All hydrogeologic conceptual models contain a certain amount of uncertainty and can be improved with additional data and analysis. The Eastern San Joaquin Subbasin HCM data gaps are present in the understanding of the HCM presented in this GSP. While recent efforts have been made to address these data gaps, as noted below, the following data gap elements still require additional information and will be updated with future monitoring, modeling, and data refinement efforts.

Aquifer Characteristics
o Aquifer characteristics (such as hydraulic conductivity) have a significant impact on how projects and management actions in one part of the Subbasin may influence sustainability in other parts of the Subbasin.

While this data gap has been filled to some extent with the airborne electromagnetic (AEM) data collected by DWR and the boring logs from the new monitoring wells constructed in the Subbasin, improving the understanding of the Subbasin aquifer system and leading to the addition of a shallow alluvium layer and other refinements to ESJWRM numerical flow model refinements, much still remains unknown. Aquifer characteristics should be confirmed through additional aquifer testing or additional monitoring wells.

Groundwater Level Data
• Depth- or zone-specific water levels to assess vertical interconnection, including zones within the principal aquifer. This data gap has been partially addressed by the recent construction of the two Technical Support System (TSS) and Delta multi-completion well.
• Additional shallow groundwater data near surface waters and natural communities commonly associated with groundwater (NCCAGs). This data gap has been partially addressed by the recent construction of five new shallow monitoring wells near interconnected surface waters. • Additional groundwater level data in the east and northwest areas of the Subbasin. This data gap has been partially addressed by recent improvements to the groundwater level representative monitoring network. See Chapter 4 for additional information.
• Additional groundwater level data near major creeks and rivers to improve quantification and understanding of subsurface flows between groundwater subbasins and surface water-groundwater interaction. This data gap has been partially addressed by the recent construction of five new shallow monitoring wells near interconnected surface waters and formation of a representative monitoring network specific for monitoring impacts to interconnected surface waters.

Groundwater Quality Data
• Water quality of the three zones within the principal aquifer. This data gap has been partially addressed through recent refinements to the representative monitoring network for groundwater quality. See Chapter 4 for additional information.
o Additional monitoring at various depths for different constituents will help inform the understanding of water quality. This can be achieved through installation of new monitoring wells or through determination of screened intervals of existing monitoring wells. o Additional depth-specific water quality data will inform minimum thresholds for the degraded water quality sustainability indicator and help monitor and identify potential undesirable results.

Subsurface Conditions
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• Stockton Fault extent and impact on the base of fresh water. • Improved characterization of near-surface soil conditions as they relate to recharge. • Further definition of aquifer characteristics (e.g., hydraulic conductivity, transmissivity, and storage parameters) within and near Subbasin boundary areas to the east, southeast, north, and northwest, including aquifer tests.

2.2 HISTORICAL GROUNDWATER CONDITIONS
This section describes historical groundwater conditions in the Eastern San Joaquin Subbasin as of the development of the 2020 GSP. As such, this section includes both historical conditions in the Subbasin prior to 2019, and the current conditions as of the development of the 2020 GSP in 2019. These sections are maintained in the GSP to provide a context of the conditions occurring at the time the 2020 GSP was developed.

As required by the GSP regulations, the groundwater conditions section includes:
• Definition of current groundwater conditions in the Subbasin (as of 2020 GSP development) • Description of historical groundwater conditions in the Subbasin • Description of the distribution, availability (storage), and quality of groundwater • Identification of interactions between groundwater, surface water, groundwater dependent ecosystems, and subsidence
The groundwater conditions described in this section present the historical availability, quality, and distribution of groundwater which are the basis of this Plan’s sustainable management criteria and monitoring network. The current and historical conditions discussed are further expanded upon in Chapter 3: Sustainable Management Criteria and are used to define undesirable results and to establish measurable objectives, interim milestones, and minimum thresholds.

Historically, the two aspects of greatest focus for groundwater management in the Eastern San Joaquin Subbasin have been groundwater elevation and, in some areas of the Subbasin, groundwater quality. As discussed herein, a groundwater depression exists in the central portion of the Subbasin, while higher groundwater levels characterize the west portion of the Subbasin. Additionally, there are elevated levels of salinity and nitrate in some areas, along with naturally occurring constituents commonly seen throughout the Central Valley. Detailed descriptions of these conditions are provided in the following sections as part of a discussion of the historical and current conditions for each of the six sustainability indicators:
• Groundwater Elevation (Section 2.2.1)
• Groundwater Storage (Section 0)
• Seawater Intrusion (Section 0)
• Groundwater Quality (Section 2.2.4)
• Land Subsidence (Section 0)
• Interconnected Surface Water (Section 2.2.6)
Details of GDEs are provided in Section 2.2.7 and Section 2.3.7 to support the sustainability indicator discussions.

2.2.1 Groundwater Elevation
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2.2.1.1 Historical Groundwater Elevations
Data sources for groundwater elevation are abundant in the Eastern San Joaquin Subbasin. As discussed in Section 2.1, the CASGEM and San Joaquin County databases constitute the groundwater level data used for this analysis. These sources provide a robust dataset of groundwater levels going back to 1940.

To visually show long-term trends in groundwater elevations in the Eastern San Joaquin Subbasin, 10 wells that have periods-of-record greater than 40 years and that are relatively evenly distributed across the Subbasin were selected from available data (see Figure 2-42). Long-term hydrographs prepared for these wells show that, throughout most of the Eastern San Joaquin Subbasin, groundwater elevations have declined over time.

Average groundwater level decline was quantified for 1996-2015. In Section 2.3 (Water Budgets), the Historical Water Budget from the 2020 GSP uses 1996-2015 as a representative hydrologic period which includes an average annual precipitation of 14.7 inches, very close to the long-term average of 15.4 inches. The 1996-2015 period also includes the recent 2012-2015 drought, the wet years of 2010-2011, and periods of normal precipitation. Based on data from the 10 selected wells in Figure 2-42, the average groundwater level decline was -0.5 ft/year from 1996-2015.

Hydrographs for wells numbered #2, #5, and #6 show the largest decrease in groundwater elevation. These wells are located to the east of the City of Stockton. Hydrograph #9, which corresponds to a well located on the north edge of the Subbasin, shows the least decrease in groundwater elevation from 1996-2015. Hydrograph #4 corresponds with a well located in the western side of the Subbasin and is the only well to show an increasing trend in groundwater elevations. The northeast corner of the Subbasin is an area without a nearby representative hydrograph and was identified as a data gap in Section 2.1.10 (HCM Data Gaps).

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Figure 2-42: Hydrographs of Selected Wells
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Figure 2-43 shows the distribution of the groundwater elevations from the CASGEM and San Joaquin County databases compared to average precipitation in and near the Subbasin. Figure 2-43 shows an overall decreasing trend in groundwater elevation levels with larger variability over time. The increasing variability comes partly due to a larger number of wells being sampled through time in more varied topography, but also reflects the long-term changes in groundwater levels described above and in Figure 2-42.

Periods of increases in groundwater elevation moderately correspond to the amount of precipitation in the Eastern San Joaquin Subbasin. A correlating trend can be seen with groundwater elevation increases in several hydrographs in the early 1980s and late 1990s, associated with periods of high precipitation.

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Figure 2-43: Summary of Groundwater Elevation Data, 1940-2018

1. Each vertical bar in Figure 2-43 (a) represents the full range of groundwater level measurements recorded in a given year. The central gray box represents the middle 50% of measurements (ranging from the 25th percentile to the 75th percentile), with the horizontal line showing the median. The capped lines below and above the central box represent the minimum and maximum, respectively.

2. Precipitation monitoring depicted in Figure 2-43 (a) began in 1951.

3. The average annual precipitation line presented in Figure 2-43 (b) is based on an average of data collected at 7 stations which are mapped in Figure 2-44.
(b) Number of Groundwater Level Measurements
(a) Box-and-Whisker Plot with Precipitation
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Figure 2-44: Precipitation Stations

1. These stations are operated by California Irrigation Management Information System (CIMIS) (“A”), National Oceanic and Atmospheric Administration (NOAA) (“C”), and PestCast (University of California Statewide Integrated Pest Management Program [UC IPM] and Department of Pesticide Regulation [DPR]) (“P”).

Additionally, extensive reports and research examining the groundwater conditions of the Central Valley are available from a variety of sources, including the USGS and DWR. These documents supplement the water level data provided by the CASGEM and San Joaquin County databases and were used to assess current and historical groundwater elevations.

USGS Water Supply Paper 780 – One of the earliest discussions of measured groundwater levels in the Eastern San Joaquin Subbasin is the USGS Water Supply Paper 780. The report details river stage of the Mokelumne River and the surrounding groundwater table from roughly 1900 to 1930. Groundwater levels in wells around the Mokelumne River varied, but mostly declined due to an increase in groundwater pumping.

Even between years of minimal groundwater pumping, from 1927 to 1933, the water table decreased in elevation, most drastically in areas northeast and southeast of the City of Lodi (Piper et al., 1939).

DWR Bulletin 146 – DWR’s Bulletin 146 (1967) discusses water levels and flow directions in the 1960s and earlier, which provides added historical context to current groundwater conditions. Figures 4 and 5 of Bulletin 146 show groundwater elevation in most of the Eastern San Joaquin Subbasin in fall of 1950 and 1964, EXHIBIT 1
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respectively. Both maps show groundwater levels at the lowest elevation underneath the City of Stockton, which is attributed to heavy groundwater pumping. This groundwater depression is attributed as causing groundwater from the Delta to flow toward the City of Stockton and is described as having relatively worse water quality due to natural mineral salts. Barriers between the poorer quality water from the Delta and higher quality water from the Sierra Nevada Mountains noted in previous studies around the City of Stockton are not apparent (CA DWR, 1967).

Williamson, 1989 – Groundwater conditions provided in the groundwater model report by Williamson (1989) included horizontal and vertical flows. A westerly groundwater flow direction that roughly parallels the ground surface in the Eastern San Joaquin Subbasin was confirmed, as depicted on Figure 14 of that report.

Estimates of groundwater elevations for before-human-development were provided. Vertical flow characteristics before considerable human development were characterized and mapped; areas of wells that flowed without pumps are shown throughout the valley and in the western portion of the Eastern San Joaquin Subbasin. This is in contrast to current conditions, where wells flowing without pumps have not been currently observed in the Subbasin. At present, USGS nested monitoring wells confirm downward vertical flows (Williamson, 1989).

2.2.1.2 Conditions as of 2019: Groundwater Elevations
For the purposes of the 2020 GSP, current groundwater elevation conditions were characterized as first quarter 2017 (seasonal high, measured in spring 2017) and fourth quarter 2017 (seasonal low, measured in fall 2017) groundwater elevation measurements. At the time of the 2020 GSP, those records constituted the most complete dataset.

Groundwater elevations were mapped using the CASGEM dataset (including voluntarily monitored wells) and the San Joaquin County dataset.

Figure 2-45 and Figure 2-46 show the groundwater elevations for the first and fourth quarters of 2017, respectively. A pumping depression at the center of the Subbasin, east of the City of Stockton, existed during both of these periods. A localized pumping depression is shown expanding from the Cosumnes Subbasin across Dry Creek to the Eastern San Joaquin Subbasin in fourth quarter of 2017. However, from the perspective of the entire Eastern San Joaquin Subbasin, the central pumping depression to the east of the City of Stockton is most significant to achieving sustainability in the Subbasin. Groundwater generally flows from the outer edges of the Subbasin towards the depression in the middle of the Subbasin. Along the eastern side of the Subbasin, the lateral gradient of groundwater levels ranged from approximately 21 feet per mile (ft/mi) during the seasonal high to 16 ft/mi during the seasonal low. Along the western side of the Subbasin, the lateral gradient rangef from approximately 7 ft/mi during the seasonal high to 6 ft/mi during the seasonal low. The steeper gradients on the east side of the Subbasin compared to the west side are primarly due to the steeper topography in that area.

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Figure 2-45: First Quarter 2017 Groundwater Elevation
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Figure 2-46: Fourth Quarter 2017 Groundwater Levels
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2.2.1.2.1 Vertical Gradients
A vertical gradient drives the movement of groundwater perpendicular to the ground surface and is typically measured by comparing the elevations of groundwater in nested and/or clustered wells, wells with multiple completions at different depths. If groundwater elevations in the shallower completions are higher than in the deeper completions, the gradient is identified as a downward gradient. A downward gradient is one where groundwater is moving downward through the subsurface. If groundwater elevations in the shallower completions are lower than in the deeper completions, the gradient is identified as an upward gradient. An upward gradient is one where groundwater is moving upward through the subsurface. If groundwater elevations are the same throughout the completions, there is no vertical gradient.

Knowledge about vertical gradients is required by regulation and is useful for understanding how groundwater moves in the Subbasin.

Vertical flow characteristics before considerable human development are characterized and mapped by Williamson (1989), showing that wells flowing without pumps existed in the western portion of the Eastern San Joaquin Subbasin, also corresponding with areas of upward vertical gradients. This contrasts with current conditions, where wells flowing without pumps have not been currently observed in the Subbasin. At present, USGS nested monitoring wells confirm downward vertical gradients (Williamson, 1989).

As of the 2020 GSP, there were 16 nested and/or clustered well sites located in the Eastern San Joaquin Subbasin.

The locations of the wells are shown in Figure 2-47. The majority of these wells are located in the northwest portion of the Subbasin near the cities of Stockton and Lodi. Hydrographs with groundwater elevations for each respective set of nested wells are shown in Figure 2-48 through Figure 2-63. 10 out of 16 sets of wells consistently show elevations in shallower completions that are higher than in the deeper completions which indicates a downward gradient. The remaining six wells are located in the City of Lodi. Four of these wells exhibit a minimal downward gradient and two show no downward gradient.

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Figure 2-47: Map of Nested and/or Clustered Well Sites (as of 2020 GSP Development) EXHIBIT 1
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Figure 2-48: Nested Well Hydrographs: CCWD 004-006 (as of 2020 GSP Development) Figure 2-49: Nested Well Hydrographs: CCWD 010-012 (as of 2020 GSP Development) EXHIBIT 1
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Figure 2-50: Nested Well Hydrographs: Sperry Well (as of 2020 GSP Development) Figure 2-51: Nested Well Hydrographs: Swenson Golf Course (as of 2020 GSP Development) EXHIBIT 1
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Figure 2-52: Nested Well Hydrographs: STK-1 (as of 2020 GSP Development) Figure 2-53: Nested Well Hydrographs: STK-2 (as of 2020 GSP Development) EXHIBIT 1
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Figure 2-54: Nested Well Hydrographs: STK-4 (as of 2020 GSP Development) Figure 2-55: Nested Well Hydrographs: STK-5 (as of 2020 GSP Development) EXHIBIT 1
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Figure 2-56: Nested Well Hydrographs: STK-6 (as of 2020 GSP Development) Figure 2-57: Nested Well Hydrographs: STK-7 (as of 2020 GSP Development) EXHIBIT 1
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Figure 2-58: Nested Well Hydrographs: Lodi MW-21 (as of 2020 GSP Development) Figure 2-59: Nested Well Hydrographs: Lodi MW-24 (as of 2020 GSP Development) EXHIBIT 1
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Figure 2-60: Nested Well Hydrographs: Lodi MW-25 (as of 2020 GSP Development) Figure 2-61: Nested Well Hydrographs: Lodi SMW-1 (as of 2020 GSP Development) EXHIBIT 1
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Figure 2-62: Nested Well Hydrographs: Lodi WMW-1 (as of 2020 GSP Development) Figure 2-63: Nested Well Hydrographs: Lodi WMW-2 (as of 2020 GSP Development) EXHIBIT 1
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2.2.2 Groundwater Storage
The ESJWRM was used to estimate historical change in storage of the Eastern San Joaquin Subbasin from 1995-2023.

Figure 2-64 shows annual total storage for the combined ESJWRM Version 3.0 fresh groundwater layers (not including the deep saline layer). Figure 2-65 shows the cumulative change in storage against annual storage change and water year type. In 2015, the total fresh groundwater storage was estimated as 74.0 million acre-feet (MAF). An additional

95.0 MAF in the deepest simulated layer of the model (not pictured) is saline water. More information about the layers of the ESJWRM Version 3.0 and calculation of storage changes can be found in model documentation in Appendix 2- C.

Figure 2-64: Historical Modeled Change in Storage
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Figure 2-65: Historical Modeled Change in Annual Storage with Water Use and Year Type Notes:

1. Water Year Types based on San Joaquin Valley Water Year Index (CA DWR, 2024)

2. “Other Recharge” includes managed aquifer recharge, recharge from unlined canals and/or reservoirs, and recharge from ungauged watersheds.

3. “Change in Storage” is placed to balance the water budget. For instance, if annual outflows (-) are greater than inflows (+), there is a decrease in storage, but this would be shown on the positive side of the bar chart to balance out the increased outflows on the negative side of the bar chart.

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2.2.3 Seawater Intrusion
The Eastern San Joaquin Subbasin is not in a coastal area and seawater intrusion is not present. While the Delta ecosystem evolved with a natural salinity cycle that brought brackish tidal water in from the San Francisco Bay, levees installed to allow development of agriculture, followed by development and operation of the Central Valley Project and the State Water Project, have altered the inward movement of seawater through the Delta. Current management practices endeavor to maintain freshwater flows through a combination of hydraulic and physical barriers and alterations to existing channels (Water Education Foundation, 2019). Portions of the Subbasin do, however, experience water quality issues related to salinity, which are addressed under Section 2.2.4.1 (Salinity). As described in Section

2.2.4.1, salinity in the Subbasin is due to other factors and are not the result of seawater intrusion.

2.2.4 Conditions as of 2019: Groundwater Quality
While groundwater quality in the Eastern San Joaquin Subbasin is generally sufficient to meet beneficial uses, a number of constituents of concern are either currently impacting groundwater use or have the potential to impact it in the future. Depending on the water quality constituent, the source may be anthropogenic in origin or naturally occurring, and the issue may be widespread or localized.

The primary naturally occurring water quality constituents of concern are salinity and arsenic, while the primary water quality constituents related to human activity include nitrates, salinity, and various point-source contaminants.

The sections herein provide information on the historical and current (as of the 2020 GSP) groundwater quality conditions for constituents including:
• Salinity (Section 2.2.4.1)
• Nitrate (Section 2.2.4.2)
• Arsenic (Section 2.2.4.3)
• Point-source contamination (Section 2.2.4.4), which includes petroleum hydrocarbons, solvents, and emerging contaminants
CCR Title 22 establishes water quality standards for drinking water contaminants. A primary maximum contaminant level (MCL) or SMCL is defined for a variety of parameters. For the purposes of this GSP, comparing parameter concentrations to their MCL or SMCL is used as the basis for describing groundwater quality concerns in the Eastern San Joaquin Subbasin. Comparisons to the MCL or SMCL must be considered in context as the measured concentrations represent raw water that may be treated or blended prior to delivery to meet the standard or may not be used for potable uses. Water quality is generally not known to have significantly adversely affected beneficial uses of groundwater in the Eastern San Joaquin Subbasin.

2.2.4.1 Salinity
As identified in prior planning efforts, and as referenced in Section 2.2 (Historical Groundwater Conditions) and Section

2.3 (Current Groundwater Conditions), localized salinity issues are a concern for some areas of the Eastern San Joaquin Subbasin. Pumping in excess of recharge has resulted in declining groundwater levels that have contributed to an increase of salinity in groundwater wells since the 1950s. As identified through isotopic typing, elevated salinity concentrations in the Subbasin are the result of natural processes and overlying land use activities (O’Leary et al., 2015). Within the Subbasin, there are three primary sources of salinity:

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1. Delta Sediments – Evaporation of groundwater in discharge areas introduces naturally occurring soluble salts into Delta sediments.

2. Deep Deposits – Saline groundwater in the Subbasin is principally the result of the migration of a naturally occurring deep saline water body which originates in regionally deposited marine sedimentary rocks that underlie the San Joaquin Valley. This results in a saline aquifer underlying the freshwater aquifer, and well pumping can result in upwelling saline brines into the freshwater aquifer.

3. Irrigation Return Water – Irrigation return water is excess applied water that percolates into the groundwater system or flows to the stream system from an irrigated field following the application of irrigation water. Return water may include contaminants typical of agricultural practices (e.g., pesticides, herbicides) and can concentrate salts due to evapotranspiration. The return water may act as a conduit delivering these contaminants to the surrounding watershed or underlying groundwater aquifer. Areas in the Subbasin with salinity resulting from irrigation return water do not commonly exceed chloride concentrations of 100 mg/L (O’Leary et al., 2015).

Salinity is a measure of the mass of dissolved particles and ions in a volume of water. Salinity includes many different ions, including nitrate, but the most common are sodium, calcium, magnesium, chloride, bicarbonate, and sulfate.

Chloride and TDS are two common ways to measure and analyze salinity. Each is described separately in the sections below.

2.2.4.1.1 Chloride
Chloride is one way to measure salinity and is reported as a concentration of the Clion that originates from the dissociation of salts in water. The California Department of Drinking Water (DDW) SMCL of 250 mg/L for chloride is a common approach to identifying water quality concerns for this constituent. The SMCL is a secondary drinking water standard that is established for aesthetic reasons such as taste, odor, and color and is not based on public health concerns. The 250 mg/L value is “recommended” by SWRCB as a threshold below which chloride concentrations are desirable for a higher degree of consumer acceptance of drinking water. An “upper” limit of 500 mg/L is used to define a range above the “recommended” value where chloride concentration is acceptable if it is neither reasonable nor feasible to provide more suitable waters (SWRCB, 2018). Comparisons to the SMCL must be considered in context as the measured concentrations represent raw water, which may be treated or blended prior to delivery to meet the standard or may not be used for potable uses.

As shown in Figure 2-66, the majority of observed chloride concentrations above 250 mg/L occur on the western side of the Subbasin. As shown in Figure 2-67, the number of measurements with observed concentrations above 250 mg/L has decreased since the 1970s. The GAMA dataset was used for analysis.

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Figure 2-66: Maximum Chloride Concentration Greater Than 250 mg/L (1940s-2010s) EXHIBIT 1
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Figure 2-67: Maximum Chloride Concentration Above 250 mg/L by Decade EXHIBIT 1
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Table 2-5 shows occurrence of chloride measurements greater than 250 mg/L by decade. Chloride records have been observed above 250 mg/L both historically and more recently. Sampling frequencies increased in the 1970s and 2000s.

Table 2-5: Summary of Chloride Data by Decade
Decade Measurement Above
250 mg/L? Range of Values (mg/L) Total Number
of Samples
No Yes Minimum Average Median Maximum
1940 98% 2% 7.0 45.2 20.0 975 180
1950 93% 7% 2.3 89.4 25.0 3,750 699
1960 90% 10% 0.0 115.0 17.0 1,960 312
1970 90% 10% 1.8 85.9 19.0 3,310 1,780
1980 97% 3% 0.0 45.4 20.5 630 858
1990 99% 1% 0.0 31.2 19.0 533 663
2000 95% 5% 0.0 59.6 35.0 2,050 1,453
2010 98% 3% 0.0 34.8 39.0 2,050 986
Table 2-6 shows chloride occurrences of concentrations greater than 250 mg/L by well depth. The highest proportion of readings above 250 mg/L occur in the shallowest wells, less than 100 feet deep (8 percent). The highest maximum value also occurred at this depth range (up to 2,050 mg/L).

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Figure 2-68 shows the spatial distribution of chloride occurrences greater than 250 mg/L by well depth within the Subbasin.

Table 2-6: Summary of Chloride Data by Depth (1940s-2010s) Depth (feet) Measurement Above
250 mg/L? Range of Values (mg/L) Total Number
of Samples
No Yes Minimum Average Median Maximum
No Depth Data 92% 8% 0.0 82.5 20.0 3,750 3,566
0 - 100 92% 8% 0.8 73.5 60.0 2,050 239
100 - 250 97% 3% 1.0 44.2 36.0 1,400 1,215
250 - 500 98% 2% 0.0 32.4 16.0 1,100 1,487
> 500 95% 5% 2.7 62.1 15.6 1,940 424
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A lack of depth information presents a challenge to analyzing the vertical distribution of chloride measurements which would inform identification of chloride sources. Examples of depth information include total well construction depth or screened interval depths, which vary between wells. Some wells have total depth but not screened interval depth, or vice versa. For this analysis, screened interval depth was used first, and if this information was not available, total depth was used. Approximately 4,600 of the almost 13,000 chloride measurements in the Eastern San Joaquin Subbasin are from wells lacking any construction or screen depth information. Roughly half of the measurements above 250 mg/L occur in the wells lacking depth data, which also show the highest range in values occurring above 250 mg/L.

Identifying the source of high-chloride water in wells of various depths over time requires further analysis of geochemical data.

2.2.4.1.2 Total Dissolved Solids (TDS)
TDS, which is a measure of all inorganic and organic substances present in a liquid in molecular, ionized, or colloidal suspended form, is commonly used to measure salinity. Recent TDS sample results show trends that match closely with the overall historical trends for chloride and highlight areas with elevated salinity concentrations in more recent years. TDS concentrations in the Eastern San Joaquin Subbasin ranged from 35 to 2,500 mg/L between 2015 and 2018. Spatially, the highest concentrations of TDS are found along the western margin of the Subbasin and the San Joaquin River and decrease significantly to the east, to typically less than 500 mg/L. TDS measurements, like chloride levels, are elevated near the cities of Stockton and Manteca, and in the Lodi GSA near the White Slough Water Pollution Control Facility.

Figure 2-69 shows the maximum and Figure 2-70 shows the average TDS concentrations from 2015 to 2018 as compared to the SMCL lower limit of 500 mg/L and upper limit of 1,000 mg/L. The GAMA dataset was used for analysis.

The SMCL is a secondary drinking water standard that is established for aesthetic reasons such as taste, odor, and color and is not based on public health concerns. The 500 mg/L value is “recommended” by the State Water Resources Control Board (SWRCB) as a threshold below which TDS concentrations are desirable for a higher degree of consumer acceptance of drinking water. The “upper” limit is used to define a range above the “recommended” value where TDS concentration is acceptable if it is neither reasonable nor feasible to provide more suitable waters (SWRCB, 2006).

Comparisons to the SMCL must be considered in context as the measured concentrations represent raw water, which may be treated or blended prior to delivery to meet the standard or may not be used for potable uses.

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Figure 2-69: Maximum TDS Concentrations 2015-2018
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Figure 2-70: Average TDS Concentrations 2015-2018
Elevated TDS concentrations are apparent in very shallow groundwater in close proximity to the San Joaquin River, while deep wells (depths greater than 200 feet) typically have TDS concentrations below 500 mg/L. TDS trends by depth are summarized in Table 2-7
Figure 2-71 shows the maximum TDS concentrations for shallow wells in the Eastern San Joaquin Subbasin from years 2015 to 2018, and Figure 2-72 shows the maximum TDS concentrations for deep wells in the same timeframe.

As with chloride measurements, depth-dependent TDS data are not widely available.

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Table 2-7: Summary of TDS Data by Depth (2015-2018)
% Measurements in Range Range of Values (mg/L) Total
Depth (feet) < 500
mg/L
500 – 1000
mg/L
> 1,000
mg/L Minimum Average Median Maximum Number of Samples
No Depth
Data 90% 8% 2% 94 339 310 1,180 451
0 - 100 N/A 0
100 - 250 54% 46% 0% 280 438 480 540 13
250 - 500 93% 7% 0% 120 344 340 560 75
> 500 N/A 0
Figure 2-71: Maximum TDS Concentrations in Shallow Wells 2015-2018 EXHIBIT 1
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Figure 2-72: Maximum TDS Concentrations in Deep Wells 2015-2018 EXHIBIT 1
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2.2.4.2 Nitrate
Nitrate is both naturally occurring and can be contributed a result of human activity. Nitrate can cause adverse human health effects. Anthropogenic sources of nitrate include fertilizers, septic systems, and animal waste. The DDW’s MCL of 10 mg/L for Nitrate as N delimits high levels of nitrate for drinking water use. Many measured concentrations are above this value, both historically and more recently. Comparisons to the MCL must be considered in context as the measured concentrations represent raw water, which may be treated or blended prior to delivery to meet the standard or may not be used for potable uses.

Table 2-8 provides the total number of nitrate values by decade and the percentage of those values greater than 10 mg/L. The total number of nitrate measurements has grown since 2000 as has the percentage of occurrences of concentrations greater than 10 mg/L. The GAMA dataset was used for analysis.

Table 2-8: Nitrate as N Concentrations by Decade
% of Samples
Decade <10 mg/L >10 mg/L Number of Nitrate Samples
1940 88% 13% 8
1950 99% 1% 362
1960 99% 1% 240
1970 96% 4% 1,500
1980 95% 5% 420
1990 98% 2% 1,716
2000 87% 13% 9,679
2010 83% 17% 11,060
Figure 2-73 shows the historical spatial distribution of nitrate samples and detections by decade. During the 1940s, the earliest decade with nitrate measurements, very few records exist, and no significant conclusions can be made from this timeframe. The 1950s and 1960s have larger datasets, but measurements above 10 mg/L during these decades are sporadic and localized. Nitrate concentrations during the 1970s show a significant number of measurements above 10 mg/L in the northwest portion of the Eastern San Joaquin Subbasin, adjacent to Interstate 5. The 1980s and 1990s show similar patterns, with areas measurements above 10 mg/L primarily around the cities of Stockton, Lodi, and Manteca. Nitrate as N measurements above 10 mg/L are also located near the southern edge of the Eastern San Joaquin Subbasin, close to Highway 120. Although a much greater number of records exists for the 1990s than the 1980s, these decades have approximately the same spatial distribution. One possible explanation is similar wells were sampled during the 1980s and 1990s, but much more frequently in the 1990s. The 2000s and 2010s had both the greatest number of nitrate measurements and the largest number of measurements above 10 mg/L. Measurements above 10 mg/L during these decades follow previous trends: they are primarily between Highway 99 and Interstate 5, from Ripon to near Lodi.

Recent (as of 2019) nitrate measurements above the MCL correspond to the overall historical trends and highlight areas with elevated nitrate concentrations in more recent years. These areas include the cities of Stockton and Ripon, areas of the Lodi GSA near the White Slough Pollution Control Facility, the N.A. Chaderjian Youth Correctional Facility, Republic Services Landfill on South Austin Road, and the Kruger and Sons, Inc. site off Highway 4 outside Farmington.

While the extent of groundwater quality impacts from nitrate is a data gap area, increased nitrate concentrations have not been found to have a causal nexus between SGMA-related groundwater management activities in the Subbasin.

The causal nexus reflects that the degraded water quality issues are associated with groundwater pumping and other SGMA-related activities rather than water quality issues resulting from land use practices, naturally occurring water quality issues, or other issues not associated with groundwater pumping. Additional monitoring conducted through the implementation of this GSP will inform trends such that the Eastern San Joaquin Groundwater Authority (ESJGWA) can be informed to take action to address nitrite contamination if a causal nexus is identified.

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Section 3.3 of this Plan discusses Irrigated Lands Regulatory Program (ILRP) and Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS), two existing regulatory programs for the monitoring and regulation of nitrate.

Under the ILRP, the San Joaquin County & Delta Water Quality Coalition is required to test and potentially mitigate for nitrate in domestic wells. Additionally, the 2017 Salt and Nitrate Management Plan developed by CV-SALTS identifies long-term nitrate management practices (CVRWQCB, 2016).

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Figure 2-73: Nitrate as N Concentrations by Decade
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2.2.4.3 Arsenic
Arsenic is ubiquitous in nature and is commonly found in drinking water sources in California. Determining the source of arsenic in groundwater is difficult because arsenic is both naturally occurring and used in human activities such as agriculture. Public health concerns about arsenic in drinking water related to its potential to cause adverse health effects are addressed through DDW’s MCL, established at 10 micrograms per liter (µg/L). California's revised arsenic MCL of 10 μg/L became effective on November 28, 2008. A 10-μg/L federal MCL for arsenic has been in effect since January 2006. Previous California and federal MCLs for arsenic were 50 μg/L.

Figure 2-74 shows the spatial distribution of arsenic concentrations contained in the GAMA database. From the 1970s to present, the total number and percentage of arsenic values above 10 µg/L has increased (see Table 2-9). The spatial distribution of measurements above 10 µg/L is similar to nitrate, largely between Interstate 5 and Highway 99, from Manteca to Lodi. The increased arsenic concentrations near urban areas are not necessarily indicative of contamination from these areas and may partially be due to the fact that arsenic measurements are more abundant in these urban areas; GAMA water quality records are rarely evenly distributed throughout the Subbasin for any constituent. Recent (as of 2019) arsenic samples show measurements above 10 µg/L similar to the overall trends (see Figure 2-75). Measurements above 10 µg/L in years 2015, 2016, 2017, and 2018 are primarily located in the cities of Stockton and Manteca, with fewer occurring around the City of Lodi. While the extent of groundwater quality impacts from arsenic is a data gap area, increased arsenic concentrations have not been found to have a causal nexus between SGMA-related groundwater management activities in the Subbasin.

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Figure 2-74: Arsenic Concentrations by Decade
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Table 2-9: Arsenic Concentrations by Decade
% of Samples
Decade <10 µg/L >10 µg/L Number of Arsenic Samples
1960 100% 0% 1
1970 86% 14% 339
1980 72% 28% 363
1990 72% 28% 645
2000 56% 44% 4,051
2010 48% 52% 5,109
Figure 2-75: Maximum Arsenic Concentrations 2015-2018
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2.2.4.4 Point Sources
Point sources are discrete or discernable sources of pollutants which may introduce undesirable constituents into groundwater and may negatively impact water quality. In the Eastern San Joaquin Subbasin, point sources include leaking underground storage tanks, landfills, dry cleaners, and others. These sites are actively investigated and monitored within the Eastern San Joaquin Subbasin in response to these known or potential sources of groundwater contamination.

The Regional Water Quality Control Board (RWQCB), the Department of Toxic Substances Control (DTSC), and the USEPA provide oversight of point-source pollution through existing regulatory programs, including management of remedial action for point-source contamination sites. Figure 2-76 shows the results of a query from both the GeoTracker database and the EnviroStor database. GeoTracker documents contaminant concerns that the RWQCB is or has been working with site owners to remediate while EnviroStor is the DTSC’s data management system to track known contamination sites undergoing cleanup, permitting, enforcement, and investigation efforts. As shown in Figure 2-76, there are 258 active sites within the Eastern San Joaquin Subbasin which are color-coded based on the site’s constituent(s) of concern: fuels (gas and/or diesel); synthetic organics (pesticides, herbicides, insecticides, etc.); or a mix of constituents (multiple constituents such as heavy metals and pesticides).

Most sites within the Eastern San Joaquin Subbasin are fuel sites (e.g., gas or diesel) that are under active investigation or remediation. Sites with the potential to cause plumes are mapped in Figure 2-77, which were identified by filtering for sites containing soluble and mobile constituents such as volatile organic compounds (VOCs); benzene, toluene, ethylbenzene, and xylenes (BTEX); and/or petroleum hydrocarbons (gas or diesel).

Sites with the potential to cause plumes are currently managed by existing regulatory programs through the RWQCB, DTSC, and USEPA, as described above. New projects undertaken by the GSAs as part of GSP implementation will evaluate contaminant plume movement in a CEQA document. Specific point source sites and contaminants are discussed in the sections below.

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Figure 2-76: Active Investigation and Remediation Sites as of 2019 EXHIBIT 1
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Figure 2-77: Active Sites with the Potential to Cause Plumes

2.2.4.4.1 Publicized Plumes in and near the Subbasin
As indicated above, the Eastern San Joaquin Subbasin has numerous open cleanup sites, including areas contaminated by chlorinated solvents, methyl tertiary-butyl ether (MtBE), pesticides and herbicides, and leaking underground storage tanks. Plume sites are often clustered around urban centers but are also found near sites where historical industrial or agricultural practices have released contaminants of concern. While other plumes exist in and around the Subbasin, three specific plumes have been highly publicized: the Lodi Plumes, the Sharpe Army Depot Plume, and the Occidental Chemical Corporation Plume.

In the late 1980s, the City of Lodi discovered the chlorinated solvents perchloroethylene (PCE) and trichloroethene (TCE) in drinking water supplies and pursued a groundwater investigation that revealed a series of five separate plume areas located in the northeastern portion of the city: the Northern, Western, Central, Southern, and Busy Bee plumes.

The Busy Bee plume, named after a dry cleaner business that previously operated on the site, now has regulatory closure, with cleanup moving toward completion under CVRWQCB oversite (Water Resources Control Board, 2011).

Groundwater contamination plumes in the City of Lathrop, located just outside the Subbasin boundary, include the Sharpe Army Depot and Occidental Chemical Corporation sites. Contamination of groundwater at the Sharpe Army EXHIBIT 1
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Depot consists primarily of trichloroethene, tetrachloroethene, and cis-1,2-dichloroethene from historical industrial activities related to military activities. Due to concerns of potential contamination, the City of Lathrop abandoned their wells in the area. Three groundwater extraction and treatment systems are located at Sharpe Army Dept and are used to treat existing groundwater (EKI Environment & Water, 2015).

The Occidental Chemical Corporation Plume was discovered in the late 1970s and is the result of former leaking wastewater holding ponds containing pesticides and chemicals used for equipment cleaning by the Occidental Chemical Corporation. Contaminants of concern include the pesticides 1,2-dibromo-3-chloropropane (DBCP) and ethylene dibromide (EDB), lindane, 2,3,4,5-tetrahydrothiopene-1, 1-dioxide, sulfate, nitrate, chloride, and BHC (RWQCB, 2012). Since the discovery of these plumes in the 1980s, groundwater monitoring and evaluation at point source locations has led to the implementation of remedial activities such as the installation of groundwater extraction and remedial systems, implementation of a Salinity Reduction Plan, and mandated waste discharge requirements (WDRs) (CVRWQCB, 2012).

2.2.4.4.2 Petroleum Hydrocarbons
Approximately 134 sites in the Eastern San Joaquin Subbasin are identified as actively investigating or remediating an unauthorized release of petroleum hydrocarbons, according to the GeoTracker and EnviroStor databases. At these sites, petroleum hydrocarbon constituents are most commonly fuels (diesel, gasoline, motor oil, or aviation fuel) and VOCs commonly added to fuels, including MTBE and BTEX constituents. Concentrations of petroleum hydrocarbons have not been modeled across the Subbasin; concentrations are local and site specific. A summary description of the aforementioned constituents is provided in Table 2-10 below:

Table 2-10: MCLs for Common Petroleum Hydrocarbons and MTBE Constituent Source Primary MCL
MTBE Oxygenate commonly added to gasoline 13 µg/L
BTEX
Benzene Industrial solvent added to crude oil paint, varnish, and lacquer thinner 1 µg/L
Toluene Aromatic hydrocarbon used in industrial feedstock, as a solvent, and to produce benzene and added to gasoline 150 µg/L
Ethylbenzene Used as a solvent and added to fuel, asphalt, and naphthalene 300 µg/L Xylenes Naturally occurring in petroleum, coal and wood tar 1.750 mg/L Source: (SWRCB, 2018)

2.2.4.4.3 Synthetic Organics
Approximately 47 sites in the Eastern San Joaquin Subbasin are identified as actively investigating or remediating an unauthorized release of synthetic organics, according to the GeoTracker and EnviroStor databases. At these sites, pesticides, herbicides, fertilizer, and pesticides are the most common constituents. Other constituents include VOCs such as PCE and TCE. Concentrations of synthetic organics have not been modeled across the Subbasin; concentrations are local and site specific. For context, a brief description of the aforementioned VOCs is provided in Table 2-11.

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Table 2-11: MCLs for Common Synthetic Organic Constituents Constituent Source Primary MCL1
TCE Used as a solvent in manufacturing facilities and dry cleaners 5 µg/L PCE Used as a solvent in manufacturing facilities, dry cleaners, printing shops, and auto repair facilities 5 µg/L
Note:
1 Source: (SWRCB, 2018)

2.2.4.4.4 Mixed Constituents
Approximately 28 sites in the Eastern San Joaquin Subbasin are identified as actively investigating or remediating an unauthorized release of mixed constituents, according to the GeoTracker and EnviroStor databases. Sites with mixed constituents are those that include a release of more than one type of contaminant, such as a mix of heavy metals, diesel, inorganics, and/or organics. At these sites, the most common constituents include a mixture of heavy metals (chromium, arsenic, and lead), inorganics, and solvents. The sources and primary MCL for many contaminants found in the ‘mixed constituents’ classification have been discussed throughout Section 2.2.4.

2.2.4.4.5 Emerging Contaminants
Many chemical and microbial constituents that have not historically been considered as contaminants are occasionally, and in some cases with increasing frequency, detected in groundwater. These newly recognized (or emerging) contaminants are commonly derived from municipal, agricultural, industrial wastewater, and domestic wastewater sources and pathways. These newly recognized contaminants are dispersed to the environment from domestic, commercial, and industrial uses of common household products and include caffeine, artificial sweeteners, pharmaceuticals, cleaning products, and other personal care products. Residual waste products of genetically modified organisms are also of potential concern. Several studies, such as by Watanabe et al. in 2010, have recently been published or are underway regarding the potential link between dairies and the occurrence of pharmaceuticals in shallow groundwater in the San Joaquin Valley.

Perfluorooctanesulfonic acid (PFOS) and perfluorooctantoic acid (PFOA) are organic chemicals synthesized for water and lipid resistance, used in a wide variety of consumer products as well as fire-retarding foam and various industrial processes. These chemicals tend to accumulate in groundwater, though typically in a localized area in association with a specific facility, such as a factory or airfield (California Water Boards, 2018). There are currently no MCLs for PFOS or PFOA; however, the USEPA is moving forward with establishing the MCL and is recommending municipalities notify customers at levels at or greater than 70 parts per trillion in water supplies (USEPA, 2019). California’s DDW has established notification levels at 6.5 parts per trillion for PFOS and 5.1 parts per trillion for PFOA (SWRCB, 2019). 1,2,3-Trichloropropane (1,2,3-TCP) is a solvent and is typically found in industrial or hazardous waste sites. Along with an industrial solvent, 1,2,3-TCP is a cleaning and degreasing agent and associated with pesticide products. Though there is currently no federal MCL, the MCL for 1,2,3-TCP in California is 0.005 µg/L (SWRCB, 2019).

Currently, data on PFOS, PFOA, and 1,2,3-TCP are limited in the Eastern San Joaquin Subbasin since these are emerging contaminants.

2.2.5 Conditions in 2019: Land Subsidence
Despite long-term declining groundwater levels, there are no historical records of significant and unreasonable impacts from subsidence in the Eastern San Joaquin Subbasin. Figure 2-78 shows regional subsidence produced from TRE Altamira Interferometric Synthetic Aperture Radar (InSAR) data, provided by DWR for SGMA application. InSAR is a satellite-based method for showing ground-surface displacement over time. This figure illustrates that subsidence has historically been minimal in the Subbasin and surrounding areas (ranging from -0.1 to 0.1 feet of vertical displacement annually). The error range of a single InSAR measurement is +/- 5 millimeters (TRE Altamira, 2019). See Section 2.1.5 for a discussion of the soils and clays within the Subbasin, including the extent of Corcoran Clay.

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Figure 2-78: Subsidence (Annual Rate of Vertical Displacement) Note: This dataset represents measurements of vertical ground surface displacement in between spring 2015 and summer 2017 (TRE Altamira, 2019).

2.2.6 Conditions in 2019: Interconnected Surface Water Systems Interconnected surface waters (ISW) are surface water features that are hydraulically connected by a saturated zone to the groundwater system. In these systems, the water table and surface water features intersect at the same elevations and locations. Interconnected surface waters may be either gaining or losing, wherein the surface water feature itself is either gaining water from the aquifer system or losing water to the aquifer system.

In the Eastern San Joaquin Subbasin, stream connectivity was analyzed by comparing monthly groundwater elevations from the historical calibration of the ESJWRM to streambed elevations along the streams represented in ESJWRM.

This analysis was based on modeling results from the historical calibration of the ESJWRM for approximately 900 stream nodes in the Eastern San Joaquin Subbasin, which represents that best available information for current and historical conditions related to interconnected surface water systems. Figure 2-79 shows locations where streams EXHIBIT 1
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are interconnected at least 75 percent of the time (shown in blue) or interconnected less than 25 percent of the time (shown in green).

Disconnected streams will always be losing streams, but interconnected streams may be either losing or gaining, depending on the surface water and groundwater conditions. Groundwater discharge from the aquifer is primarily through groundwater pumping, however, groundwater also discharges to streams where groundwater elevations are higher than the streambed elevations. Figure 2-80 shows mostly gaining streams in blue where groundwater discharges to rivers more than 75 percent of the time, mostly losing streams in red where streams lose water to the groundwater system more than 75 percent of the time, and mixed streams (gaining or losing less than 75 percent of the time) in orange.

Due to limited model calibration based on insufficient calibration information, stream nodes in the Delta area and along stretches of streams near the foothill boundary of the Subbasin are not shown on Figure 2-79 and Figure 2-80.

Interconnected surface water is highlighted as a data gap in Section 4.7.3 due to a lack of data from shallow monitoring wells near streams. Future improvements to the understanding of interconnected surface water include proposed monitoring wells in Section 4.7.5 that are largely located along streams or in areas of the foothills where current monitoring coverage is lacking and a specific project in Section 6.2 to improve understanding of losses along Mokelumne River. Section 7.4.1 discusses model refinements over the next five years in order to improve calibration of the model and its use in analysis of GSP water budgets and sustainability criteria. The analysis in this section includes the results from the 2019 model and Appendix 3-G details an updated analysis.

Figure 2-79 and Figure 2-80 are illustrations to describe model outputs, which are subject to uncertainty and future refinements and are not intended for regulatory purposes beyond the use in this Plan.

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Figure 2-79: Stream Connectivity to the Groundwater System Note: Analysis is based on limited data recognized to have significant gaps. Interconnected surface water is a recognized data gap in the GSP as discussed in Section 4.7.

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Figure 2-80: Losing and Gaining Streams
Note: Analysis is based on limited data recognized to have significant gaps. Interconnected surface water is a recognized data gap in the GSP as discussed in Section 4.7.

2.2.7 Conditions in 2019: Groundwater-Dependent Ecosystems Groundwater-dependent ecosystems (GDEs) are defined in the GSP regulations as “ecological communities or species that depend on groundwater emerging from aquifers or on groundwater occurring near the ground surface.” SGMA requires the identification of GDEs. SGMA does not require that additional sustainable management criteria be established to specifically manage these areas, but rather includes GDEs as a beneficial user of water to be considered when developing other sustainable management criteria.

GDEs exist where vegetation accesses shallow groundwater for survival. This Plan identifies GDEs within the Eastern San Joaquin Subbasin based on determining the areas where vegetation is dependent on groundwater.

2.2.7.1 Methodology for GDE Identification
The Natural Communities Commonly Associated with Groundwater (NCCAG) database was used as a starting point to identify GDEs within the Subbasin. The NCCAG database was developed by a working group comprised of DWR, California Department of Fish and Wildlife (CDFW), and The Nature Conservancy (TNC). The working group reviewed EXHIBIT 1
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publicly available datasets which mapped California vegetation, wetlands, springs, and seeps and conducted a screening process to retain communities known to be commonly associated with groundwater. The NCCAG database defines two habitat classes: wetland and vegetative. The wetland class includes wetland features commonly associated with the surface expression of groundwater under natural, unmodified conditions. The vegetative class includes vegetation types commonly associated with the shallow subsurface presence of groundwater (phreatophytes). Figure 2-81 shows the location of the two NCCAG classes within the Eastern San Joaquin Subbasin. The distribution of freshwater fish and wildlife species that may be dependent on GDEs is not well known and is not included in this analysis. A list of freshwater species in the Eastern San Joaquin Subbasin is provided in Appendix 1-H. Instream flows for rivers and streams interconnected with groundwater are evaluated through the Depletions of Interconnected Surface Water sustainability indicator (see Section 3.3.6).

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Figure 2-81: Natural Communities Commonly Associated with Groundwater (NCCAGs) Source: NC Dataset Viewer, CADWR Sustainable Groundwater Management (https://gis.water.ca.gov/app/NCDatasetViewer/) EXHIBIT 1
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This Plan uses the NCCAG database as a starting point for identifying potential GDEs. To identify NCCAG areas that are potential GDEs, the analysis identified communities in areas where groundwater levels are shallower than 30 feet bgs, as these areas are thought to be reachable by the root zone of vegetation.1 Oak trees are considered the deepestrooted plant in the region with a root zone of roughly 25 feet.2 This value is considered conservative, as this depth is unlikely to support recruitment of new oak seedlings. NCCAG-identified communities in areas with groundwater shallower than 30 feet were considered as potential GDEs. Communities in areas deeper than 30 feet were identified as data gap areas for future refinement and are labeled on Figure 2-82 as “Depth to Water > 30 ft”. These areas will be refined in future analyses to identify potential existing GDEs that may have been misclassified through this screening process. Additional information regarding plans to fill GDE-related data gaps can be found in Section 4.7.4.

The NCCAG database was then further refined to identify communities without access to alternate water supplies, as those communities would not be dependent on groundwater. This was done by screening for the following: 1) areas not close to managed wetlands, 2) areas not adjacent to irrigated agriculture, and 3) areas not near perennial surface water bodies. NCCAG-identified communities with access to shallow water (less than 30 feet bgs) and without access to alternate water supplies were classified as GDEs. Communities with access to alternate water supplies were identified as data gap areas requiring additional investigation to determine the reliability of the alternate supply. • Proximity to Managed Wetlands – Managed wetlands receive supplemental water to support wildlife habitat.

Managed wetlands, and areas within 150 feet of a managed wetland, are assumed to be able to access this supplemental delivered water regardless of the condition of the underlying aquifer. Areas farther than 150 feet from a managed wetland that meet the other GDE criteria in this section are assumed to be dependent on groundwater and were identified as GDEs. A criterion of 150 feet was used to reflect ponded conditions at the wetlands. Identified wetlands were reviewed with local water managers to verify supplemental water deliveries.

NCCAG-identified communities not identified as GDEs through this analysis are identified as data gap areas for future refinement and are labeled on Figure 2-82 as “Managed Wetland”. These areas will be refined in future analyses to determine if the alternate source of surface water is reliable over time and to identify potential existing GDEs that may have been misclassified through this screening process. • Adjacent to Irrigated Agriculture – Irrigated agricultural lands are dependent on regular irrigation. This irrigation benefits not only the crops, but also the surrounding vegetation. Irrigated lands, and areas within 50 feet of irrigated lands, are assumed to be able to access this supplemental delivered water regardless of the condition of the underlying aquifer. Areas farther than 50 feet from irrigated lands that meet the other GDE criteria in this section are assumed to be dependent on groundwater and were identified as GDEs. A criterion of 50 feet was used to reflect non-ponded conditions in the fields.

NCCAG-identified communities not identified as GDEs through this analysis are identified as data gap areas for future refinement and are labeled on Figure 2-82 as “Adjacent to Agriculture”. These areas will be refined in future analyses to determine if the alternate source of surface water is reliable over time and to identify potential existing GDEs that may have been misclassified through this screening process. • Proximity to Perennial Surface Water Bodies – Perennial surface water bodies provide year-round water supplies that can be accessed by adjacent vegetation. These water bodies include much of the Delta; large, managed rivers; and smaller water bodies that flow throughout the summer due to agricultural deliveries or 1 This analysis uses 2015 groundwater levels (winter, spring, summer, and fall), which may be deeper than representative levels due to drought conditions, a factor which will be considered in future GDEs analyses. 2 Quercus chrysolepis (canyon live oak) has a maximum rooting depth of 7.3 meters (23.95 feet) (Canadell et al., 1996).

Quercus lobata (valley oak) has a maximum rooting depth of 7.41 meters (24.31 feet), although available data are from fractured rock aquifers (Lewis & Burgy 1964 and Schenk, H. J. and Jackson, R. B. 2002, as cited in TNC, 2019).

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tailwater. Areas within 150 feet of such surface water bodies are assumed to be able to access that surface water regardless of the condition of the underlying aquifer. Areas father than 150 feet from such surface water bodies that meet the other GDE criteria in this section are assumed to be dependent on groundwater and were identified as GDEs. A criterion of 150 feet was used to reflect open water conditions in the surface water bodies.

NCCAG-identified communities not identified as GDEs through this analysis are identified as data gap areas for future refinement and are labeled on Figure 2-82 as “Perennial Surface Water Bodies”. These areas will be refined in future analyses to determine if the alternate source of surface water is reliable over time and to identify potential existing GDEs that may have been misclassified through this screening process.

Next, areas identified as GDEs were ground-truthed electronically with GSA staff and Groundwater Sustainability Workgroup (Workgroup) members. Through this process, areas identified GDEs were investigated, and areas identified as known irrigated parcels such as parks were reclassified. These areas are labels on Figure 2-82 as “Stakeholder Comment.”
This methodology was developed to focus groundwater management activities on the most appropriate areas. The distinction between GDEs and other wetland or vegetative areas is important from a management perspective, as GDEs are expected to be more responsive to changes in groundwater management. Management of communities that access alternate supplies, on the other hand, may require greater focus on land use protection or irrigation activities, for which the GSAs have limited authority to manage through SGMA.

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Figure 2-82: NCCAGs Identified as Data Gap Areas for Future Refinement, Likely to Access Non-groundwater Water Supplies EXHIBIT 1
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2.2.7.2 Areas Identified as GDEs
Following the methodology presented above, this Plan identifies several GDEs, primarily located along the western boundary of the Subbasin and in the Delta areas where groundwater is typically shallow. These areas are divided into two categories: Vegetative GDEs and Wetland GDEs, as shown in Figure 2-83.

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Figure 2-83: Areas Identified as GDEs
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2.3 CURRENT GROUNDWATER CONDITIONS
This section describes the current groundwater conditions in the Eastern San Joaquin Subbasin since development of the 2020 GSP.

As required by the GSP regulations, the current groundwater conditions section includes:
• Definition of current groundwater conditions in the Subbasin • Description of the distribution, availability (storage), and quality of groundwater • Identification of interactions between groundwater, surface water, groundwater dependent ecosystems, and subsidence
Current conditions are generally assumed to be the conditions of the Subbasin roughly between WY 2020 and WY 2023, unless otherwise noted in the below sections.

2.3.1 Groundwater Elevation

2.3.1.1 Groundwater Levels
For the purposes of the 2024 GSP, the most current groundwater elevation conditions were characterized as fourth quarter 2022 (recent seasonal low, measured in fall 2022) and first quarter 2023 (recent seasonal high, measured in spring 2023) groundwater elevation measurements. However, WY 2023 represented a wetter than average water year.

For comparison, fourth quarter 2019 and first quarter 2020 of WY 2020 are also included. WY 2020 was a dry year.

Groundwater elevations were mapped using wells with available data in WDL.

Figure 2-84 and Figure 2-85 show the groundwater elevations for WY 2020. Figure 2-86 and Figure 2-87 show the groundwater elevations for WY 2023. A pumping depression at the center of the Subbasin, east of the City of Stockton, generally exists during periods of lower groundwater elevations, as shown in Fourth Quarter 2019, First Quarter 2020, and Fourth Quarter 2022. In wetter years, this pumping depression can recover, as shown in First Quarter 2023. Similar to historical conditions, groundwater generally flows from the outer edges of the Subbasin towards the depression in the middle of the Subbasin. The predominant hydraulic gradient across the Subbasin is from east to west.

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Figure 2-84: Fourth Quarter 2019 Groundwater Elevation (WY 2020) EXHIBIT 1
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Figure 2-85: First Quarter 2020 Groundwater Levels (WY 2020) EXHIBIT 1
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Figure 2-86: Fourth Quarter 2022 Groundwater Elevation (WY 2023) EXHIBIT 1
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Figure 2-87: First Quarter 2023 Groundwater Levels (WY 2023) Hydrographs are reported annually to DWR in the Annual Reports for 76 single completion wells and 52 nested wells.

The most recent hydrographs for these wells can be found in the WY 2023 ESJ Subbasin Annual Report, available on DWR’s SGMA Portal (https://sgma.water.ca.gov/portal/). All hydrographs show yearly cycles of groundwater level declines in summer due to typical patterns in groundwater pumping and recharge during winter recovery.

2.3.1.2 Reported Dry Wells
According to DWR’s Dry Well Reporting System, San Joaquin County has had 106 reported dry wells since the start of WY 2020 (CA Department of Water Resources, 2023). Figure 2-88 shows the number of reports made to DWR by month between WY 2020 and WY 2023. However, it is important to note that dry wells are reported for many reasons other than a failure due to increasing depth to groundwater. Staff interviews with DWR confirmed that the system does not determine the cause of the well failure unless monitored by outside parties. As expected, reports of dry wells were higher in the critical years of WY 2021 and 2022 than in WY 2023, a wet year.

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Figure 2-88 : Number of Reported Dry Wells in San Joaquin County between WY 2020-2023

2.3.2 Groundwater Storage
The ESJWRM was used to estimate historical change in storage of the Eastern San Joaquin Subbasin from 1995-2023.

Figure 2-89 shows the cumulative change in storage against annual storage change and water year type, including current condition years WY 2020 through 2023. The cumulative change in storage from 1996 to 2023 was estimated as on average -0.34 million acre-feet per year (MAF/year). More information about the layers of the ESJWRM and calculation of storage changes can be found in model documentation in Appendix 2-C.

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Figure 2-89: Modeled Change in Annual Storage with Water Use and Year Type Notes:

4. Water Year Types based on San Joaquin Valley Water Year Index (CA DWR, 2024)

5. “Other Recharge” includes managed aquifer recharge, recharge from unlined canals and/or reservoirs, and recharge from ungauged watersheds.

6. “Change in Storage” is placed to balance the water budget. For instance, if annual outflows (-) are greater than inflows (+), there is a decrease in storage, but this would be shown on the positive side of the bar chart to balance out the increased outflows on the negative side of the bar chart.

2.3.3 Seawater Intrusion
The northwest corner of the Eastern San Joaquin (ESJ) Subbasin overlies a portion of the Delta. The Delta originally experienced groundwater fluctuations closely tied to tidal cycles, with a mix of brackish, saline ocean water, and fresh streamflow typical of an inland river delta and estuary. However, after decades of land reclamation and the implementation of managed operations as a result of the State Water Project and Central Valley Project, the Delta is now managed as a freshwater body. Saline water is no longer able to migrate eastward beyond the extensive network of levees and engineering alterations to the original natural channels. As a result, seawater intrusion has not historically been observed within the Subbasin nor is it likely to occur in the future.

The following section provides analysis supporting this claim, demonstrating that:

1. The Delta is managed as a freshwater body in the Subbasin

2. There is minimal pumping near the Delta

3. There are relatively low chloride concentrations in the Subbasin EXHIBIT 1
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Further detail can be found in Appendix 3-F.

2.3.3.1 Delta is Managed to Maintain Freshwater Flows
The Subbasin is located in the Delta region. Prior to the construction of the Shasta Dam in 1943, brackish water had entered the surface waterways throughout the Delta. The Delta ecosystem naturally adapted to a salinity cycle that brought brackish tidal water from the San Francisco Bay. However, the construction of levees for agricultural development, followed by the development and operation of the Central Valley Project and the State Water Project, has changed the pattern of seawater movement into the Delta (Water Education Foundation, 2019). Historically, some saltwater may have infiltrated the aquifers locally affecting groundwater quality. Current management practices aim to maintain freshwater flows in the Delta through a combination of hydraulic and physical barriers and modifications to existing channels (Water Education Foundation, 2019). The ”X2” barrier, where the salinity is approximately 2 parts per thousand (ppt), is located well outside of the Subbasin boundary further downstream in the Delta (Cloern, 2012). (For reference purposes, the salinity of the ocean is about 35 ppt.) Various agencies and regulations, such as the Delta Protection Commission (DPC), Delta Stewardship Council, San Joaquin County & Delta Water Quality Coalition, and State Water Board Resolution No. 2009-011, contribute to managing and maintaining salinity conditions in the Delta region.

2.3.3.2 Minimal Groundwater Pumping Near the Delta
Figure 2-90 presents the Subbasin’s 2023 average groundwater pumping in feet across the Subbasin. The majority of pumping is in the northwest portion of Subbasin, areas adjacent to the Delta pump less than half a foot of groundwater per year.

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Figure 2-90: 2023 Annual Groundwater Pumping
This figure reflects groundwater pumping from the 2023 Eastern San Joaquin Annual Report. Results may vary with the updated 2024 Eastern San Joaquin Water Resources Model.

2.3.3.3 Low Chloride Concentrations
Historical and current chloride concentrations were analyzed in the Subbasin. A variety of groundwater quality data were collected and examined. The datasets used for this analysis include (1) the Groundwater Ambient Monitoring and Assessment (GAMA) database, (2) The National Water (NWQMC) database, (3) the region’s Opti Data Management System (DMS), and (4) SGMA Data Viewer (DWR). From these datasets, 4,000 unique wells were utilized with approximately 19,500 chloride observations.

Most wells had chloride concentrations well below the SMCL of 250 mg/L for chloride. (Secondary MCLs are established as guidelines to assist public water systems in managing their drinking water for aesthetic considerations, such as taste, color, and odor. Contaminants with SMCLs are not considered to present a risk to human health and are not enforced.) Chloride concentrations throughout the Subbasin have remained relatively low. Table 2-12 shows the percentage of chloride measurements after 2015 that exceed thresholds of 250 mg/L, 500 mg/L, and 2,000 mg/L.

Notably, the majority of measurements (80%) fell within the 0–250 mg/L range, indicating low chloride levels throughout the Subbasin. Additionally, 14% of chloride observations were in the 250–500 mg/L range. Overall, 94% of measurements are below the 500 mg/L threshold. This analysis demonstrates that chloride concentrations in the Subbasin are generally low.

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Table 2-12: Chloride Concentrations after 2015
Threshold Concentration Percentage of Measurements after 2015 above Threshold
250 mg/L 14%
500 mg/L 5%
2,000 mg/L 1%
Chloride measurements in Table 2 are based on approximately 19,500 observations from 4,000 unique wells.

Figure 2-91 shows the average chloride concentration in the Subbasin since January 2015. These results are consistent with the ranges shown in Table 2-12. As shown in Figure 2-91, the majority of chloride concentrations in the Subbasin are within the 0 to 250 mg/L range. There are instances of higher concentrations in the 250 to 500 mg/L range, localized within the central and western regions of the Subbasin. Notably, these areas of relatively higher chloride concentrations are not located only in the Delta area and do not form a seawater intrusion front pattern. Overall, concentrations of chloride in the Subbasin are minimal and seawater intrusion is not occurring in the Subbasin or expected to occur in the future.

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Figure 2-91: Average Chloride Concentrations Post-2015

2.3.4 Groundwater Quality
In addition to the chloride data shown in Section 2.3.3, available recent TDS data from the Groundwater Ambient Monitoring and Assessment (GAMA) Program were also analyzed to characterize current groundwater quality conditions. The locations, observations, and concentrations of the new set of monitoring wells were examined, as shown in Figure 2-92 through Figure 2-94.

Figure 2-92 illustrates the count of TDS groundwater quality observations for each well between January 2015 and January 2024. The majority of wells have 10 or fewer observations, indicating that most wells were not sampled on an annual basis. Several wells closer to the City of Stockton have up to 50 groundwater quality observations. The wells with the highest sample count appear to be located near groundwater cleanup sites. Ideally, wells in the representative monitoring network for groundwater quality would have been sampled regularly; however, some wells in the specific areas have not sampled frequently (greater than 10 times) in recent years.

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Figure 2-93 displays wells with TDS observations in recent years (2015 through early 2024) by well depth. The threshold between shallow and deep wells was set at 200 feet for consistency with the 2020 GSP. There were several wells without perforation or depth information. Between shallow, deep, and unknown well depths, there is a similar distribution of high- and low-quality groundwater. In other words, TDS was not observed in just the shallow portions or just the deep portions of the aquifer.

Figure 2-94 illustrates the maximum TDS concentrations since January 2015. The majority of wells have TDS concentrations below 600 mg/L (the measurable objective for TDS). However, some wells have recent TDS concentrations above 1,000 mg/L (the minimum threshold for TDS). These wells are primarily located near the City of Stockton. Public water purveyors closely monitor groundwater quality and source and treat their water accordingly.

Figure 2-92: Monitoring Frequency for Wells Measuring Total Dissolved Solids EXHIBIT 1
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Figure 2-93: Wells with Recent TDS Observations by Well Depth EXHIBIT 1
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Figure 2-94: Maximum Concentrations for Wells Measuring Total Dissolved Solids

2.3.5 Land Subsidence
SGMA requires monitoring and reporting on inelastic land subsidence. In the Subbasin, subsidence concerns, if any, are focused on the non-Delta area as the Delta region contains peaty soils. Peaty soils can subside due to peaty soil oxidation. Peat oxidation occurs when the peaty soils dewater and come into contact with air, causing the soils to break down and compress, and is not a mechanism caused by groundwater overdraft.

Within the Eastern San Joaquin Subbasin, there are three primary sources of subsidence data, each with different periods of record and methods of data collection:
• CGPS vertical displacement data from the DWR SGMA Data Viewer • InSAR subsidence rates from the SGMA Data Viewer
• Survey benchmarks from U.S. Geological Survey (USGS), the U.S. Army Corps of Engineers (USACE), California Department of Transportation (CalTrans), the San Joaquin County Department of Public Works, and local agencies.

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There are no DWR or USGS extensometers in the Eastern San Joaquin Subbasin. The datasets used are detailed further below.

2.3.5.1 CGPS Data
Vertical displacement data from CGPS stations are available for download from the DWR SGMA Data Viewer (DWR, 2024). Two CGPS stations are monitored by UNAVCO and two by Scripps Orbit and Permanent Array Center (SOPAC). Of the SOPAC stations, Station P309, is the northeast region of the Subbasin north of the Calaveras River and has a period of record from March 4, 2006, to January 19, 2024. Station P273, in the northwest region of the Subbasin, has data from November 10, 2005, to December 28, 2020. P273 lies in the Delta region of the Subbasin.

City Council and Concurrent AuthoritiesMarch 18, 2025

City Council and Concurrent Authorities
March 18, 2025