Water Supply and Groundwater in San Joaquin County and Lodi

Lodi
Written By Don Bradford
Water Supply and Groundwater in San Joaquin County and Lodi

Water Supply and Groundwater in San Joaquin County and Lodi

LodiEye — September 2026

Status, trends, and who carries the risk

Overview

Lodi and eastern San Joaquin County draw on two water systems that behave very differently. One is the Mokelumne River, delivered to Lodi through a 40-year contract with Woodbridge Irrigation District and backed by some of the oldest water rights on the river. The other is the groundwater under our feet, the Eastern San Joaquin Subbasin, a 707,000-acre aquifer the state has classified as critically overdrafted, meaning more is being pumped out than is going back in. Roughly half of Lodi's drinking water comes from each.

The near-term picture is stable. Groundwater levels in the subbasin are holding, there is no measurable land subsidence, water quality at the basin scale is within targets, and Lodi has banked more than 53,000 acre-feet of unused river water since 2003. (An acre-foot is about 326,000 gallons, roughly what two or three households use in a year.) The long-term picture is not resolved. The subbasin loses about 89,000 acre-feet of storage a year on average, and the Groundwater Authority's own model says pumping must fall by about 95,000 acre-feet a year to stop the decline. Projects now funded cover about a third of that. The rest depends on a large program to store extra Mokelumne River water underground in wet years, which is still waiting on a state water-rights decision, or on a program to limit pumping that the Authority acknowledges could limit growth.

Four statewide decisions now in motion will shape which of those paths the region takes: the Delta tunnel, the Sites reservoir, the Bay-Delta Plan's flow requirements, and the Colorado River settlement. Dan Walters laid these out in a September 11 CalMatters column, “California's future water supplies depend on the outcomes of four intertwined battles,” which argues that the next few months of decisions on those four fronts will determine how water is managed and allocated for decades, with a governor trying to settle two of them before leaving office. This report takes his statewide framing and follows it down to San Joaquin County and Lodi. Three of the four fronts touch the county directly, and the nearest is the State Water Board's October 28–29 hearing on adopting the Bay-Delta Plan update, which sets the flow rules for the Mokelumne.

The risk is not evenly shared. Groundwater-dependent farms outside the surface-water districts and rural residents on private wells carry the most exposure. City of Lodi water customers carry the least in the near term, with their exposure showing up later as rates and growth limits rather than shortages.

The statewide setting

Where California's groundwater stands

The Department of Water Resources released its Spring 2026 Semi-Annual Groundwater Update in May, drawing on annual reports from more than 250 local groundwater agencies covering about 95 percent of the state's basin pumping. These agencies exist because of the 2014 Sustainable Groundwater Management Act, or SGMA, the state law that requires overdrafted basins to reach balance by 2040. DWR's summary to the California Water Commission was that near-term conditions are positive to stable while long-term deficits persist.

The Water Year 2025 numbers:

  • Pumping came in just under 13 million acre-feet, slightly above the prior year and well above the wet 2023 water year.
  • Local agencies reported 1.1 million acre-feet of managed recharge, water deliberately spread on the ground or injected into wells to refill aquifers.
  • Statewide groundwater storage fell about 1.5 million acre-feet, the first decline in three years.
  • Storage rose north of the Delta and fell in the San Joaquin Valley, which DWR tied to smaller deliveries from the state and federal water projects.
  • About 83 percent of statewide extraction is concentrated in the San Joaquin Valley.
  • Roughly 71 percent of monitored wells were stable over the past year, and the 2015–2025 comparison shows more gains than losses. The 20-year record still shows persistent decline of about 2.5 feet a year in the worst areas.

DWR's structural point is that each drought drawdown leaves a deficit the following wet years do not fully erase. The 2012–2016 and 2020–2022 droughts both produced sharp pumping increases; the recoveries in 2017 and 2023 recovered only part of the loss.

Local groundwater agencies have listed nearly 2,000 projects and management actions in their plans, about 1,000 of them supply or recharge projects, with a combined potential above 4 million acre-feet. DWR's stated priority is helping local agencies convert that potential into built projects.

The four statewide battles

Walters' column identifies four fronts. Their relevance to San Joaquin County varies.

Colorado River. Decades of conflict over allocation are coming to a head as Lakes Mead and Powell approach operational failure. Nevada has sued over federal interim rules and Arizona has threatened to follow. The county draws nothing from the Colorado. The indirect effect is that Southern California losing Colorado supply increases pressure for Delta exports, which raises the stakes on the tunnel.

Sites reservoir. The State Water Board issued a draft water-rights decision for the 1.5-million-acre-foot off-stream reservoir in early September; the governor wants it settled before leaving office. The county holds no Sites participation. The effect is indirect: new Sacramento Valley storage relieves pressure on the system as a whole.

Delta tunnel. The county is at the center of this fight. Supervisor Steve Ding, representing the Delta district, urged the Delta Stewardship Council in February to reject the state's certification that the tunnel fits the Delta Plan; the bipartisan Delta Caucus has said every affected city and county opposes the project. The Council nonetheless voted six to one in late April to reject the appeals. What remains is the State Water Board's water-rights hearing and a board decision. The tunnel does not touch Lodi's Mokelumne supply. Its exposure runs to the farms on the Delta side of the county, to salt in the western subbasin, and to the levee repairs the county has argued for as the alternative.

San Joaquin River diversions and the Bay-Delta Plan. This is the one that reaches Lodi directly. Walters describes the state pressing San Joaquin Valley farmers to reduce diversions, with mandatory cutbacks in preparation if voluntary offers fall short. He notes the conflict is worsened by “reductions in water farmers can draw from underground aquifers,” and cites projections that supply cuts could idle as many as 900,000 acres of valley farmland. The regulatory vehicle for all of this is the Bay-Delta Plan, which covers the Mokelumne as well as the San Joaquin tributaries, and which comes before the State Water Board for adoption on October 28–29.

The Bay-Delta Plan and the October 28–29 hearing

Two plans on two clocks

The Bay-Delta Water Quality Control Plan is updated in two phases by river system. Phase 1, for the Lower San Joaquin River and southern Delta, was adopted in 2018 and generally requires 40 percent of unimpaired flow from February through June on the Stanislaus, Tuolumne, and Merced. Unimpaired flow means the water that would run down a river if nothing were dammed or diverted; a 40 percent rule means at least that share has to stay in the river. Eight years later it is still tied up in litigation and water-rights implementation. Phase 2 covers the Sacramento River and its tributaries, the Delta eastside tributaries (the Calaveras, Cosumnes, and Mokelumne), interior Delta flows, and Delta outflow. Phase 2 is the one now reaching adoption, and it is the one Lodi's supply sits in.

What the final draft does

The State Water Board released its final draft on August 19, 2026, along with a final staff report responding to prior comments and a final scientific basis supplement for the voluntary agreements. The draft keeps two distinct pathways for those who hold rights to divert water: a voluntary pathway under the Healthy Rivers and Landscapes program (HRL), in which participants meet the standard through a mix of leaving water in the river and building fish habitat, and a regulatory pathway for anyone not in HRL.

The HRL package would restore more than 27,000 acres of aquatic habitat and facilitate about $2.9 billion in restoration and related actions, subject to annual reporting, triennial board review, and a dedicated science program. The Legislative Analyst's Office notes the program would run eight years and could be extended if the Board finds it effective. The Board's own description is that HRL would have regulatory effect and remain under ongoing monitoring and review.

For those who do not participate, or if HRL does not deliver the required results, the regulatory pathway is the enforceable alternative. Its default is 55 percent unimpaired flow, with allowances added in the August draft for watersheds fed mainly by rain rather than snowmelt. If the plan is adopted, the Board has said it will immediately begin developing a methodology to protect flows under both pathways.

Who is objecting

The Bureau of Reclamation filed a sharply worded objection, saying the draft does not honor the 2022 agreement (a memorandum of understanding, or MOU, and term sheet), changes the starting point for measuring how much extra water the voluntary agreements provide, cuts exports through the federal Central Valley Project and State Water Project by 125,000 acre-feet in dry and below-normal years and 175,000 in above-normal years, and sets a 55 percent regulatory default. Westlands Water District, the largest customer of the federal project, withdrew from the voluntary negotiations on September 4, saying the state was moving toward coercion. The public water agencies that signed the 2022 MOU issued a joint statement calling the August release an important step while reserving the right to press for consistency with HRL as originally proposed. The coalition that built the voluntary pathway is now split between staying in and walking out. Environmental groups have argued from the other side that 55 percent is not enough and that HRL lacks accountability.

Timeline and milestones

DateMilestone
2018Phase 1 (Lower San Joaquin/Southern Delta) adopted; litigation follows
2022MOU and term sheet for voluntary agreements signed by the state and public water agencies; East Bay MUD joins for the Mokelumne
March 2024Draft Global Agreement for HRL implementation and enforcement circulated
October 2024First draft of Phase 2 updates released; hearings and 11 topic-specific working meetings follow
July 2025Revised draft with the two-pathway structure
December 12, 2025Limited recirculation adding Chapter 13 (HRL analysis) to the staff report
January 28–30, 2026Public hearing on the revised draft; written comments due February 2
August 19, 2026Final draft plan, final staff report, and final scientific basis supplement released
September 4, 2026Westlands withdraws from voluntary negotiations
September 18, 2026Written comments on the final draft due
October 28–29, 2026Board considers adoption at a public hearing

What happens after adoption

Adoption is the end of the planning process, not the start of enforcement. The sequence that follows runs roughly: review by the state's Office of Administrative Law and approval by the U.S. EPA; the flow-protection methodology the Board has committed to start on immediately; execution of the HRL Global Agreement by participating agencies; and then a separate water-rights proceeding to write the new rules into specific permits and licenses, which is the step that actually changes how much anyone can take from the river. Phase 1 is the cautionary example: adopted in 2018, still not fully implemented in 2026. Litigation should be expected from whichever side loses on the October vote, and possibly from both.

Where the Mokelumne sits

The Mokelumne is small in the system and politically unusual. It contributes about 2.5 percent of total Delta inflow and is the only California river meeting the state's goal of doubling its salmon population, a result East Bay MUD attributes to the 1998 partnership agreement under which it releases added flows and builds habitat. EBMUD joined the voluntary approach in 2022 and is developing implementation agreements describing how Mokelumne contributions will support the Bay-Delta objectives. At the Board's January 2026 workshop, Mokelumne restoration and timed releases were credited with improving spawning capacity and adult returns, with more restoration sites planned through 2026.

That puts the river's largest rights holder inside HRL with a strong record. What is not settled in the public record is whether Woodbridge Irrigation District, North San Joaquin Water Conservation District, or the Mokelumne River Water and Power Authority are HRL parties in their own right, or whether their diversions are covered under EBMUD's contribution. That distinction matters for Lodi more than anything else in the plan:

  • If Woodbridge is inside the voluntary pathway, Lodi's 6,000 acre-feet ride with EBMUD's package and the river supply is largely settled for the program's eight-year term.
  • If Woodbridge is outside, its licenses face the 55 percent regulatory pathway directly, and the 2018 Woodbridge–EBMUD seniority suit becomes the controlling question about who releases the water.
  • MICUP's water-right application 29835, the largest recharge lever in the subbasin plan, needs the Board to approve new wet-year diversions from a river the plan is simultaneously asking to keep more water in.

Why the October hearing is the marker

If the Board adopts with both pathways intact and EBMUD's Mokelumne package inside HRL, the river half of Lodi's supply is on a known footing through the mid-2030s. If adoption slips, or the voluntary side fractures further after Westlands, the regulatory default becomes the operating assumption for every Mokelumne diverter, including Lodi's supplier, and the seniority question moves to the front. Either way, the October vote sets the terms under which the subbasin's groundwater deficit gets closed: by recharging Mokelumne water in wet years, or by curtailing pumping.

October 28–29, 2026 — State Water Resources Control Board adoption hearing, Sacramento

The Board will consider adopting the Sacramento/Delta update to the Bay-Delta Plan, the document that sets flow rules for the Mokelumne River and decides whether its diverters comply through the Healthy Rivers and Landscapes voluntary program or a regulatory default that keeps 55 percent of natural flow in the river. Written comments on the final draft are due September 18. Remote participation has been offered at prior hearings in this process. No other pending decision has as direct a bearing on Lodi's water supply.

The Eastern San Joaquin Subbasin

Governance

The subbasin covers about 1,200 square miles: San Joaquin County east of the San Joaquin River plus smaller pieces of Calaveras and Stanislaus counties. It is managed by the Eastern San Joaquin Groundwater Authority, a joint agency formed by 16 local groundwater agencies including the cities of Lodi, Stockton, and Manteca, Woodbridge Irrigation District, North San Joaquin Water Conservation District, Stockton East Water District, and San Joaquin County. DWR approved the subbasin's plan in July 2023 with eight recommended corrective actions, which the Authority addressed in a 2024 plan amendment and a 2025 Periodic Evaluation. The next formal evaluation is due in 2030; the sustainability deadline is 2040.

Overdraft

From the Authority's 2025 Periodic Evaluation, using its updated computer model of the basin:

  • Average storage loss, 2019–2023: 89,000 acre-feet per year.
  • Total loss over that period: 467,000 acre-feet, or 0.26 percent of roughly 53 million acre-feet in storage.
  • Cumulative loss since 1996: about 1.3 million acre-feet.
  • Cumulative decline began around 2012, stabilized in the wet 2017–2019 years, and resumed in 2020.
  • Sustainable yield, the amount that can be pumped each year without long-term decline: 704,000 acre-feet per year, or 713,000 with climate change.
  • Pumping reduction needed to reach zero change in storage: about 95,000 acre-feet per year.
  • Contribution from projects already funded and moving (what the plan calls Category A): about 33,000 acre-feet per year.
  • Remaining gap: about 62,000 acre-feet per year, to be closed by future projects or the Demand Management Program.

Closing the Eastern San Joaquin Overdraft

Source: Eastern San Joaquin Groundwater Authority, 2025 Periodic Evaluation (Version 3.0 model). Values in acre-feet per year.

Earlier estimates ranged from 37,000 to 90,000 acre-feet; the model has been revised several times and the Authority cautions that figures across reports are not directly comparable. The direction has been consistent: each revision has found a larger gap.

The Authority's plan states plainly that the Demand Management Program “may impact relevant city and county general plans by limiting the amount of groundwater that may be extracted,” with effects on housing requirements, growth, and the local economy. How it would apply to Lodi has not been determined.

Groundwater levels

Levels are generally stable. Of 21 representative monitoring wells, 14 are at or above their target levels. Seven show declining ten-year trends, including the Lockeford 3 Bear Creek well northeast of Lodi. Only one well, in Manteca, has dropped below the level the plan defines as unacceptable, once, in 2022.

The subbasin's defining feature is a pumping depression east of Stockton, a low spot in the water table where decades of heavy pumping have pulled levels down. It deepens in dry years and recovers in wet ones. Groundwater flows from the basin's edges toward it, generally from east to west. Lodi sits on the Mokelumne side, north of the depression, which is the more favorable position.

Dry wells are the human face of the numbers. San Joaquin County logged 106 dry-well reports from the start of Water Year 2020 through 2023, concentrated in the critically dry years of 2021 and 2022. The 2024 amendment added a Domestic Well Mitigation Program.

Subsidence

Subsidence is the sinking of the ground surface as an over-pumped aquifer compacts. Here there is essentially none. Continuous GPS stations show no measurable land-surface decline; satellite radar shows nothing above the 0.2-foot threshold; less than a foot of total subsidence was observed anywhere in the subbasin from 2015 to 2023. This is a significant advantage over the southern valley, where DWR has recorded more than six feet since SGMA passed and rates near Corcoran and El Nido reached a foot a year during droughts. DWR's new subsidence best-management practice, finalized in January 2026, will not require the kind of level-raising that southern basins face.

Recharge and supply projects

Recharge is real but small relative to the deficit. Completed or operating projects:

  • Stockton East Water District converted 2,505 acres from wells to surface water, delivering 11,570 acre-feet of river water instead of groundwater, with another 1,135 acres in planning.
  • Central San Joaquin Water Conservation District moved 5,000 acre-feet of surface water in 2023.
  • Oakdale Irrigation District's out-of-district sales program delivered 4,783 acre-feet to Eastside landowners.
  • Oakdale and South San Joaquin irrigation districts approved a ten-year transfer to Stockton East of up to 10,000 acre-feet in critical years and 20,000 in others.
  • North San Joaquin Water Conservation District, closest to Lodi, completed the DREAM banking pilot with East Bay MUD (1,000 acre-feet), the Tecklenburg recharge basin (1,500 acre-feet), and Phase 1A of the Lakso recharge basin, an 80-acre DWR-funded project on the north system.
  • Lodi's White Slough Water Pollution Control Facility expansion recharged 518 acre-feet in 2023.
  • The City of Stockton's Phase 1 recharge basin, sized at 20,000 acre-feet per year, began construction in 2025.

The large future items are all in what the plan calls Category B, meaning not expected to advance within five years:

  • MICUP, the Mokelumne Integrated Conjunctive Use Program, which would capture high river flows in wet years and store them underground, built on the Mokelumne River Water and Power Authority's water-right application 29835. Projected at 110,000 to 158,000 acre-feet per year in wet years, with implementation from 2025 to 2040. A petition to amend the application and add underground storage went to the State Board in 2024. This is the single largest lever in the plan, and its fate is tied to what the Bay-Delta Plan allows to be diverted from the Mokelumne.
  • Farmington Dam repurpose, 15,500 to 60,000 acre-feet per year, 2030–2050, dependent on a new federal feasibility study.
  • West Linden project, 5,000 to 60,000 acre-feet per year, bringing Mokelumne and Calaveras water to the area west of Linden where the water table is lowest.
  • City of Lodi surface water facility expansion and delivery pipeline, 4,750 acre-feet per year, scheduled 2030–2033.

Interconnected streams

The updated model shows the Mokelumne losing water to the aquifer upstream of its confluence with the Cosumnes and gaining water downstream. Pumping around Lodi is drawing on the river. The National Marine Fisheries Service filed a formal objection that the plan does not adequately protect salmon and sturgeon habitat from depletion, and the Authority acknowledged that limited data restricted its analysis. Five new monitoring wells were built to fill the gap. This is where SGMA and the Bay-Delta Plan will eventually meet on the ground.

Adjacent basins

The subbasin borders the South American and Cosumnes subbasins to the north, Tracy and East Contra Costa to the west, and Modesto to the south. All had plans deemed adequate except Modesto, which was found incomplete and resubmitted in 2024. Cosumnes matters most to Lodi: it shares the Mokelumne–Cosumnes river system, and the Cosumnes is the stream most often cited statewide as disconnected from its aquifer in summer. Depletion there feeds into the losing reach of the Mokelumne above the confluence.

Water quality and contamination

Salinity

The 2024 plan amendment removed seawater intrusion as a sustainability indicator. The Authority's reasoning is that the state keeps the Delta fresh by releasing reservoir water to hold salt water back at a set point (known as X2), pumping near the Delta is minimal, and measured chloride is low. Chloride, a marker for salt, is now tracked as a water-quality measure instead, with a threshold of 250 milligrams per liter (mg/L). Current readings: 80 percent of chloride samples below 250 mg/L, 94 percent below 500, with higher values confined to the central and western subbasin and not advancing as a front. Total dissolved solids, the overall measure of salts and minerals, are below the 600 mg/L target at most wells; a small number exceed the 1,000 mg/L threshold near Stockton.

The Authority's current position, then, is that the eastward-migrating poor-quality front documented in earlier years is a salinity problem, not a seawater one, and is contained. That conclusion rests on the state continuing to hold the salt line where it is, which is itself a function of Delta operations, tunnel decisions, and flow rules.

Legacy solvents in Lodi

This is the city's largest standing water-quality cost. Nine of Lodi's wells run carbon filtration to remove TCE and PCE, industrial and dry-cleaning solvents that leaked into the aquifer decades ago and spread as plumes under north and central Lodi. PFAS, the so-called forever chemicals used in nonstick and stain-resistant products, has been detected in at least one well, with carbon treatment planned.

Agricultural contaminants

The valley-wide pattern from U.S. Geological Survey studies: nitrate above 2 mg/L is human-caused, from fertilizer and septic systems; it concentrates on the valley's eastern edge where soils are permeable and recharge is fast; and it declines with well depth and groundwater age. Wells near rivers that show a river-water recharge signature carry less nitrate. Both halves of that apply to Lodi. Vineyard country is nitrate country, and the Mokelumne corridor is the mitigating influence. Two soil fumigants once used on farms, 1,2,3-TCP and DBCP, are the other agricultural legacy found across the valley.

Naturally occurring arsenic

About 10 percent of San Joaquin Valley drinking-water wells since 2010 have exceeded the arsenic standard of 10 micrograms per liter, with high values associated with alkaline or low-oxygen conditions underground. USGS trend work found more wells with arsenic falling (16.6 percent) than rising (7.2 percent), because pumping pulls younger, oxygenated agricultural recharge downward. The trade-off is rising nitrate where arsenic falls. Rising arsenic clusters in deeper wells and the valley trough. Deepening a well, the usual response to falling levels, tends to draw older water with more arsenic, uranium, and radium.

What SGMA does and does not watch

The Authority reports no water-quality threshold exceedances and expects none in five years. That statement covers only what the groundwater plan's monitoring network samples: total dissolved solids and chloride. Nitrate, arsenic, solvents, fumigants, and PFAS are regulated through drinking-water and Regional Water Board programs, not the sustainability plan. A clean SGMA report does not mean a clean aquifer.

Lodi's position

Lodi's water system is separate from the county districts. The surface water treatment plant, in service since 2012, treats Mokelumne water purchased from Woodbridge Irrigation District under a 40-year contract for up to 6,000 acre-feet a year through 2047, at a cost of about $1.2 million a year. The plant is designed for 8 million gallons a day and can run at 10. Twenty-eight wells with combined capacity of 35,200 gallons per minute provide the other half.

Three facts distinguish Lodi from most valley cities its size:

  1. Banked water. Because Lodi could not use its full allocation before the plant opened, it accumulated 53,534 acre-feet of banked Mokelumne water, nearly nine years of the contract volume.
  2. Senior rights. Woodbridge holds among the oldest rights on the Mokelumne. Woodbridge sued East Bay MUD in 2018 over releases, arguing its licenses carry seniority. If the state ever orders diversions cut back, the answer to that question decides who gets cut first, and Lodi's supply rides on Woodbridge's answer.
  3. Two independent sources. The river and the aquifer fail for different reasons at different times.

Lodi's exposure runs through three channels. The Mokelumne channel is the Bay-Delta Plan, described above: if Woodbridge's diversions sit inside the voluntary program with EBMUD, the supply is largely insulated; if they sit outside, they face the 55 percent regulatory pathway and the seniority dispute decides who gives up water first. The groundwater channel is the Demand Management Program: Lodi is one of 16 agencies sharing one basin, and the Authority has said the program could reach into growth policy. The cost channel is treatment: solvents and PFAS are already a line item, and the General Plan's expansion of the plant to 10 million gallons a day is projected for 2030–2040.

Risks and trends by sector

Agriculture

Agriculture is the subbasin's largest user, and the 95,000-acre-foot reduction has to come mostly from irrigated land. Exposure splits sharply by location and by access to surface water.

Growers inside surface-water districts (Woodbridge, Stockton East, Central San Joaquin, North San Joaquin's south system) are the most protected. They have a supply that is not groundwater, district infrastructure being modernized with state and federal grants, and a district voice on the Authority board. Their risk is the price of that water and, for Mokelumne districts, the Bay-Delta Plan outcome.

Growers on private wells outside district boundaries — the Eastside groundwater agency area east of Stockton, the area west of Linden where the water table is lowest, the Lockeford–Clements corridor, and county-service-area lands with no district — carry the highest exposure in the county. They pump from the parts of the basin that are declining, they have no surface alternative unless a project like West Linden or the Eastside sales program reaches them, and they are the natural target of any pumping limits the Authority sets. North San Joaquin's new groundwater charge and the Oakdale purchase requirement (a minimum 1.5 acre-feet per irrigated acre when surplus water is available) show the direction: pay for surface water or accept pumping limits.

Delta-side farms face a different risk set: the tunnel's construction footprint and long-term effects on Delta salinity and levee priority, plus the western-subbasin TDS readings already above threshold near Stockton.

Winegrape growers around Lodi sit in between. Drip irrigation has cut their applied water, which is good for the deficit but also cut the incidental recharge that flood irrigation once provided; the Woodbridge district itself made that argument years ago. Vineyards have limited ability to fallow in a dry year the way row crops can, and the cost of a well going dry in a permanent crop is measured in replanting years, not one season's revenue.

Trends: surface-water conversion continuing where districts can deliver it; a shift toward paying for recharge and banking; farmland retirement pressure that the Legislature acknowledged this month by loosening rules on converting preserved farmland to solar; and the Walters-cited projection of up to 900,000 acres idled statewide if flow cuts and groundwater limits land together.

Industry

Lodi's water-using industries are wineries, food processing, and the packaging and logistics operations that support them. Their risk is indirect but not small.

  • Discharge. Winery and food-processing wastewater is high in salts and organics. Stricter Regional Board salinity management and the Authority's new chloride threshold make disposal a constraint before supply is.
  • Rates and charges. Groundwater agency fees, district charges, and city rate increases to fund treatment and plant expansion land on large users first.
  • Growth. The Demand Management Program's potential effect on general plans limits the land and connections available for expansion, which matters for a city pursuing industrial development on its edges.
  • Reliability. Industrial customers inside Lodi's system share the city's two-source resilience. Those on private wells in unincorporated areas share the growers' exposure.

Residents

City of Lodi customers carry the lowest near-term risk in the county. Two sources, banked water, senior river rights, and dozens of wells make a supply interruption unlikely. Their exposure is deferred: rates to fund PFAS and solvent treatment, plant expansion, and any Authority cost-sharing; and the growth and housing effects of a basin-wide pumping limit.

Residents in Stockton and the central subbasin live over the pumping depression, where TDS already exceeds threshold at some wells and the city is investing in well rehabilitation and wellhead treatment.

Rural residents on private domestic wells and small community systems face the highest residential risk. Domestic wells are shallower than agricultural wells and go dry first, which is what the 106 county reports in 2020–2023 recorded. They are also the wells most exposed to nitrate on the east side and to arsenic where deepening is the fix. Small systems in Lockeford, Linden, and unincorporated areas have limited ability to fund treatment. The new Domestic Well Mitigation Program is the safety net, and it is untested.

Ranking

Highest exposure to lowest:

  1. Groundwater-only farms outside surface-water districts, especially east and northeast of the pumping depression.
  2. Rural residents on private domestic wells and small community water systems.
  3. Delta-side agriculture, for tunnel and salinity reasons.
  4. Winegrape growers and processors around Lodi, whose risk is cost and permanence rather than shortage.
  5. Water-intensive industry inside city systems, exposed mainly through discharge rules and rates.
  6. City of Lodi residential customers.

What to watch

  • October 28–29: the Bay-Delta Plan adoption hearing. Whether the Board adopts on schedule, whether both pathways survive intact, and whether the Mokelumne stays inside the voluntary package. This decides Lodi's river supply and whether MICUP can be built at the scale the subbasin plan counts on. Comments are due September 18.
  • Who else leaves after Westlands. If the September 4 withdrawal starts a wider exit from the voluntary negotiations, the 55 percent regulatory default becomes the operating assumption.
  • Woodbridge's status under HRL. Whether Lodi's supplier is a party to the voluntary program or outside it, which the public record does not yet make clear.
  • The Delta tunnel water-rights hearing. A hearing-officer opinion is expected in 2026.
  • The Demand Management Program. How the Authority allocates a 62,000-acre-foot gap among 16 agencies, and whether that reaches Lodi's general plan.
  • The Woodbridge–EBMUD seniority dispute. The controlling question if the state ever orders Mokelumne diversions cut back.
  • The 2030 Periodic Evaluation. The next point at which the deficit number gets re-run and the state gets a formal look at progress.
  • Dry-well counts in the next dry year. The simplest indicator of whether the mitigation program and recharge work are reaching the people most exposed.

LodiEye is the original civic-reporting and analysis arm of Lodi411.com, a citizen-run civic data and transparency platform serving Lodi, California and San Joaquin County. LodiEye gathers information of public interest, applies editorial judgment to public records, meetings, and data, and publishes original explanatory reporting for its readers — the work of a newsroom, and a representative of the news media as that term is defined under federal law. Our reporting emphasizes primary sources, public data, and full source transparency so readers can check every claim. LodiEye complements, and does not replace, the other outlets covering this region; for additional reporting on Lodi, San Joaquin County, and the broader region, we also encourage readers to consult the Lodi News-Sentinel, Stocktonia, The Sacramento Bee, CalMatters, and other established news organizations. Our full editorial standards and news-media-status statement is published at lodi411.com/editorial-standards.

This LodiEye report was produced using artificial intelligence tools under the direction and review of the founder. Lodi411 uses multiple AI platforms in its research and publication workflow, including Anthropic's Claude (primarily Opus and Sonnet models) and Perplexity AI across a variety of large language models offered by each. These tools were used in the following capacities:

Source Discovery: AI-assisted search and retrieval identified the State Water Board's August 2026 Bay-Delta Plan documents and hearing notice, the Department of Water Resources' Spring 2026 groundwater update and its May 2026 Water Commission briefing, the Eastern San Joaquin Groundwater Authority's 2025 Periodic Evaluation and annual reports, U.S. Geological Survey groundwater-quality studies for the San Joaquin Valley, and reporting from CalMatters, Maven's Notebook, and the Legislative Analyst's Office. Perplexity AI was used for initial source discovery and real-time data retrieval; Claude was used for deeper analysis of identified sources.

Credibility Validation: AI cross-referenced claims across multiple independent sources, prioritizing agency documents (State Water Board, DWR, the Groundwater Authority, USGS, the Bureau of Reclamation), then institutional analysis (Legislative Analyst's Office), then news reporting. Multiple AI models were used to independently verify key data points and flag inconsistencies, including the several different overdraft estimates the Authority has published across model versions.

Analysis and Synthesis: Claude Opus and Sonnet assisted in mapping the four statewide water conflicts described by CalMatters onto San Joaquin County's specific supply sources, reconciling the subbasin's storage-loss and pumping-reduction figures across reports, tracing the Bay-Delta Plan's two-pathway structure to its effect on Mokelumne diverters, and building the sector-by-sector risk ranking.

Presentation: Claude assisted in drafting, structuring, and formatting the report for clarity and readability, including the overdraft-gap chart, the Bay-Delta Plan milestone table, the October hearing callout, and the ranked exposure list.

Final Review: Multiple AI models reviewed the completed draft for factual consistency, source attribution accuracy, logical coherence, and balanced presentation. Throughout the process, the editor sets the report's goals, scope, and tone; creates and shapes draft content; reviews and edits the report; integrates independent fact checks; and reviews the AI cross-checks and validations. Multi-tool cross-checking across independent models and sources is the primary error-reduction mechanism.

Lodi411/LodiEye believes that transparency about how our research is produced — including our use of AI under human direction — strengthens trust with readers and the broader information ecosystem. Readers who spot an error are encouraged to write editor@lodi411.com so we can correct it.

References

Questions and corrections: editor@lodi411.com

Don Bradford
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Lodi Finance Committee - September 16, 2026