CALIFORNIA GROUNDWATER

California’s Sustainable Groundwater Management Act (SGMA), explained

What California’s Sustainable Groundwater Management Act requires — groundwater sustainability agencies and plans, 2040/2042 deadlines, state intervention — and what it means for farms, land values and new water users.

By Argos Tellus · Updated October 2, 2026

KEY TAKEAWAYS

Groundwater supplies roughly 40% of California’s water in an average year and more in droughts, according to the Public Policy Institute of California (PPIC).
The Sustainable Groundwater Management Act (SGMA), signed in 2014, requires local groundwater sustainability agencies (GSAs) in the state’s 94 high- and medium-priority basins to adopt and carry out groundwater sustainability plans.
The 21 critically overdrafted basins must reach sustainability by 2040; other high- and medium-priority basins by 2042.
Basins whose plans the Department of Water Resources (DWR) finds inadequate move to the State Water Resources Control Board, which can place them on probation and ultimately intervene — the Tulare Lake subbasin was the first sent down that path.
In practice SGMA means pumping limits, fees and land fallowing in overdrafted basins — and a direct link between groundwater rules and farmland value.

Why California passed SGMA

For most of its history California regulated surface water but left most groundwater pumping unmanaged. During droughts, when surface supplies were cut, farms and towns pumped more — lowering water tables, drying shallow domestic wells and causing severe land subsidence, especially in the San Joaquin Valley (see groundwater depletion).

In 2014, in the middle of a historic drought, the Legislature passed and Governor Jerry Brown signed the Sustainable Groundwater Management Act, the state’s first comprehensive framework for managing groundwater at the basin level.

What SGMA requires

Basin prioritization — DWR ranks California’s groundwater basins; SGMA applies to high- and medium-priority basins (94 of them).
Groundwater sustainability agencies — local agencies (counties, water and irrigation districts) formed GSAs to manage each basin or subbasin.
Groundwater sustainability plans (GSPs) — each basin must adopt a plan with measurable objectives to avoid six “undesirable results”: chronic lowering of groundwater levels, reduction of storage, seawater intrusion, degraded water quality, land subsidence and depletion of interconnected surface water.
Deadlines — critically overdrafted basins (21) had to submit plans by January 2020 and reach sustainability by 2040; other high- and medium-priority basins submitted by January 2022 and must reach sustainability by 2042.
Tools — GSAs can require well metering, set pumping allocations and fees, and fund recharge projects.

State intervention: probation and the State Water Board

DWR reviews every plan. If a plan is found inadequate, the basin is referred to the State Water Resources Control Board. The Board can place the basin on probation — requiring pumpers to report extraction and pay fees — and, if problems persist, adopt an interim plan that the state enforces directly.

In March 2023 DWR found several San Joaquin Valley plans inadequate, including the Tulare Lake subbasin’s, which the State Water Board subsequently placed on probation in 2024 — the first basin to reach that stage under SGMA.

What SGMA means for farms, land and new water users

Bringing pumping into balance with recharge in overdrafted basins means using less groundwater. In the San Joaquin Valley, that is expected to require fallowing a substantial amount of irrigated farmland over the coming decades, alongside new recharge and water-trading projects.

That makes SGMA a land-value and credit issue, not just an environmental one. The value of irrigated land now depends on the basin’s plan, the parcel’s pumping allocation and how fast local water levels are moving — the same questions covered in farmland groundwater risk for agricultural lending. New industrial users, from food processors to data centers, must fit within GSA allocations rather than simply drilling a well.

Frequently asked questions

What is SGMA?

The Sustainable Groundwater Management Act, signed in 2014, is California’s law requiring local groundwater sustainability agencies in high- and medium-priority basins to adopt and implement plans that bring groundwater use into balance.

When do California groundwater basins have to be sustainable under SGMA?

Critically overdrafted basins by 2040 and other high- and medium-priority basins by 2042.

How many basins does SGMA cover?

SGMA applies to California’s 94 high- and medium-priority groundwater basins, including 21 critically overdrafted basins.

What happens if a groundwater sustainability plan is inadequate?

DWR refers the basin to the State Water Resources Control Board, which can place it on probation, require extraction reporting and fees, and ultimately impose an interim plan. The Tulare Lake subbasin was the first basin placed on probation.

How much of California’s water comes from groundwater?

Roughly 40% in an average year and more during droughts, according to the Public Policy Institute of California.

HOW ARGOS HELPS

Phreatic — groundwater availability

Water-level forecasts, saturated-thickness tracking and sustainable pump rates for a parcel’s wells.

Data Vault — environmental data

Keep well, water-level and compliance records for every site in one place.

SOURCES

Figures are taken from the primary sources above and dated as of the update shown. Concentrations are expressed in mg/L. Spot an error? Email support@argostellus.com.

RELATED GUIDES

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