2024 GROUNDWATER SUSTAINABILITY
PLAN ADOPTION
Stockton City Council
City of Stockton Groundwater Sustainability Agency
February 4, 2025
Agenda Item No. 15.2
Municipal Utilities Department (MUD)
Water Utility
• Treat & deliver high‐quality drinking water to
the community
Wastewater Utility
• Collect, treat and recover wastewater for the
greater Stockton area
Stormwater Utility
• Collect & discharge surface runoff in City to
rivers and local flood basins
City of Stockton Water Service Areas
• MUD serves North and
South Stockton
• California Water Service
Company serves Central
Stockton
Drinking Water ‐ Surface Water Sources
• San Joaquin and Mokelumne Rivers
• Treated at City’s Delta Water Treatment Plant
• Calaveras and Stanislaus Rivers
• Treated at Stockton East Water District Water Treatment Plant 4 Drinking Water ‐ Groundwater Supplies
• Groundwater wells ensure continued water supply, quality, reliability, and drought resiliency for the City.
• Used conjunctively with surface water supplies
• North Stockton ‐ 6 active wells
• South Stockton ‐ 3 active wells
South Stockton System Water Well #8
• Project ‐ Well Rehabilitation
• Location –E r n i e Shropshire
Park
• Project Cost ‐ $4.8M
• Project Completion ‐ 2024
• Capacity – 1,500 gpm
Sustainable Groundwater Management Act
• California State law passed
in 2014
• Sustainable Groundwater
Management Act, or
SGMA, is statewide
legislation that establishes
a path for the sustainable
local management of
groundwater
• Includes Urban,
Agricultural and
Environmental Interests
Groundwater Basin Setting
• The Eastern San Joaquin
Groundwater Subbasin
(Subbasin) is one of 21 basins
identified by the California
Department of Water
Resources (DWR) as being in a
state of critical overdraft
• SGMA requires formation of
Groundwater Sustainability
Agencies and preparation of a
Groundwater Sustainability
Plan (GSP)
Eastern San Joaquin Groundwater Authority
• Joint Powers Authority
of 16 Groundwater
Sustainability Agencies
• Includes Cities, County,
Irrigation Districts &
Water Agencies
What Does SGMA Require?
• Groundwater Sustainability Agencies (GSAs) must prepare and submit Groundwater Sustainability Plans (GSPs)
• GSPs must include measurable objectives and milestones to achieve sustainability within 20 years of adoption
• GSAs must assess progress after initial GSP submittal through Periodic Evaluations (PEs)
• GSP development must be open and transparent
• Updates every 5 years
• First GSP adopted and submitted to State in 2020
The 2024 GSP –W h a t ’ s In It?
1. Agency Information, Plan Area, & Communication
2. Basin Setting
• Hydrogeologic Conceptual Model
• Current & Historical Conditions
• Water Budget
3. Sustainable Management Criteria
4. Monitoring Networks
5. Data Management System
6. Projects & Management Actions
7. Plan Implementation
8. References
Statewide Basin Sustainability Indicators
• Chronic Lowering of Groundwater Levels
• Reduction in Groundwater Storage
• Seawater Intrusion
• Degraded Water Quality
• Land Subsidence
• Depletion of Inter‐connected Surface Water
Periodic Evaluation & Plan Submission
• SGMA requires that GSAs evaluate the GSP every 5 years and whenever the Plan is amended to:
• Status of groundwater conditions
• Meeting interim milestones & measurable objectives
• Advancement of projects and management actions
• ESJ Subbasin first Periodic Evaluation along with the 2024 Amended GSP
• Together, these documents address the eight (8) Recommended Corrective Actions
Department of Water Resources
Recommended Corrective Actions (RCAs)
5) Add additional justification
for 2,000 mg/L chloride
isocontour line
6) Revise ISW SMC and
monitoring network
7) Improve Rep MN for GWQ
8) Develop chloride isocontour
line in western portion of
Subbasin
1) Justify GWL MT and
undesirable results
2) Revise subsidence SMC using
direct subsidence monitoring
data
3) Update water budgets using
recalibrated model
4) Revise estimate for reduction
of groundwater storage volume
and UR definition
2024 GSP Amendment & Periodic Evaluation
GWA continues to make significant progress toward
achieving sustainability goals. This progress includes 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
• GSP and other documents published on ESJ Groundwater Authority Website: esjgroundwater .org
Recommendation
• 2024 GSP recommended by Water Advisory Group
and Council Water Committee (October 2024)
• City Council, acting as the GSA, adopt the ESJ
Subbasin 2024 Groundwater Sustainability Plan
Amendment and all other recommended actions
GWA –A c t i o n s to Complete 5‐Year Update
Address 8
recommended
corrective actions
Prepare 2024 GSP
Amendment Prepare Subbasin’s first
Periodic Evaluation
Hold public open
house & public
review period
GSA adoption of GSP
Amendment & approval
of Periodic Evaluation
Submit all
documentation
GSP Development Timeline
GWA submits first GSP to Dept. Water
Resources (DWR)
January 2020✓
DWR completed review & identifies GSP
deficiencies
January 2022✓
GWA submits 2022 revised GSPJuly 2022✓
GWA receives DWR GSP approval with 8
corrective actions
July 2023✓
Presentation of 2024 GSP to City Water
Advisory Group and Council Water Committee
October 2024
✓
City Council Adoption