On a journey with SGMA

California’s Sustainable Groundwater Management Act works to achieve a sustainable solution.
BY SARGEANT J. GREEN
This portion of the California Aqueduct is in the high desert in Southern California, which is part of the area that cannot get all of its water since the capacity has dropped due to subsidence.

California adopted a “new” groundwater law in 2014. It’s called the Sustainable Groundwater Management Act, also known as SGMA. It has been around long enough that we have a pretty good idea of how it works. Let me explain.

First, some history is in order. It is often presumed that California has had no groundwater laws. Actually, California has had numerous groundwater policy and law changes over time. The result is that groundwater management in California has been a journey, not an event. Previous activities laid important foundations now ingrained in SGMA. The big difference is the new law has enforceable goals. However, SGMA will still be a journey.


California has had numerous groundwater policy and law changes over time. The result is that groundwater management in California has been a journey, not an event.


California groundwater “rights” were substantially settled in the early 20th century. The right is a “proportionate share” for property of overlying landowners but also allows for “appropriators” such as cities who move water as municipalities, not landowners. Surface water rights were fully governed by legislation in 1914 using a permit structure. SGMA was adopted exactly 100 years later.  

While groundwater regulation has taken longer, it has had several key milestones spanning from groundwater management being added to California water law in 1961 to a critical drought in the mid 1970s leading to a review of water rights law to new and changing water laws throughout the 1990s and early 2000s.

Final impacts

The final event that brought SGMA to fruition was the 2011 to 2017 California drought. By 2013, the impacts of drought-related groundwater pumping became very visible. Two impacts stood out. One was the loss of shallow water by small domestic wells throughout the state with some whole subareas going dry. The poster child for area-wide loss was a small San Joaquin Valley community above the City of Porterville called East Porterville. 

California subsidence map from 2010-2015

The other impact, sinking land, was presented using new visuals created by a novel radar technique that colorfully showed the areas sinking due to the collapse of clay layers in the deeper subsurface. This impact, which geologists call “subsidence,” eventually caused a loss of capacity in three major water transportation facilities. The Fresno to Bakersfield Friant-Kern Canal on the east side of the San Joaquin Valley lost 40% of its ability to move water. The California Aqueduct on the west side of the Valley lost 20%, and a flood bypass channel of the San Joaquin River going north lost 30%. 

The impacts created an ongoing inability to timely deliver water to agriculture and cities, including Southern California, and a threat of flooding of thousands of acres of land. The evidence heavily points the finger at the San Joaquin Valley as ground zero for drought-related impacts on groundwater, and it is the largest contiguous area of critically over-drafted groundwater. But other areas and issues influenced the scope of the new law including coastal seawater intrusion and many groundwater basins with water quality issues. 

Breaking down SGMA

So how does SGMA work? The new law has the following elements: 

  • Governance is “bottom-up to top-down.”

The law gives responsibility of groundwater management to new local agencies (bottom-up) called groundwater sustainability agencies. Eligibility requires having previous authority in governing water supply, water management or land use. The new agency has to meet SGMA requirements by certain dates or the state will take over administration (top-down). The agency can be formed by a single eligible entity or multiple entities, but groundwater basins with multiple agencies must develop a coordination agreement to meet the overall needs of the basin. SGMA gives agencies the ability to register wells, purchase land and services, establish fees (including extraction fees), and assign extraction allocations to stabilize groundwater levels or take other specified actions needed to meet the goals of the law.

  • The goal of the law is to avoid “undesirable results.”

Undesirable results include avoiding six things: unsustainable lowering of groundwater levels, unsustainable loss of groundwater in storage, seawater intrusion, degraded water quality, land subsidence and surface water depletion. 

  • The tool to meet the goals is a prescriptive groundwater sustainability plan.

The Department of Water Resources was given the role of developing the prescription for most of the groundwater sustainability plans, as well as conducting the technical review of the adequacy of the plans. However, the California State Water Resources Control Board regulates water quality, so they have responsibility for oversight of the water quality part of the plans. The board is also the agency responsible for enforcing water rights in California. As a result, they are the agency that can ultimately enforce SGMA if the local agencies fail to meet the timelines or their own groundwater sustainability plan. The plan has to have specific goals and proposed remedies to avoid the undesirable results. A key part of the groundwater sustainability plan performance evaluation is the monitoring network, which also has a top-down state approval process to assure data consistency. The other key evaluation tool required is benchmarks. Specifically, water elevation thresholds are the benchmarks used to prove that the remedies applied are meeting approved goals.

SGMA has a timetable as to who had to comply when, and the highest priority basins that were declared critically overdrafted by the Department of Water Resources were first. Twenty-one basins were given that distinction, but three were in the middle of court adjudications where the users in the basin sued each other so 18 moved forward. Today we have 260 new local groundwater sustainability agencies, and the critically overdrafted areas have complete coverage. 

All the critically overdrafted areas submitted their groundwater sustainability plans on time in January 2020 and the Department of Water Resources is still reviewing those comprehensive documents. Many plans exceed 2,000 pages of information when appendices are included. The plans include projects that increase recharge or reduce pumping. 

Land Subsidence Specialist Michelle Sneed in the San Joaquin Valley southwest of Mendota, California, at the approximate location of the maximum subsidence in the United States.

Based on analyses by outside experts, the findings in the area with the most extensive area of overdraft, the San Joaquin Valley, are that there is not enough water supply or recharge options to cover the existing uses. Other experts estimate as much as 1 million acres of land will have to come out of agricultural production in the Valley to achieve “sustainability.” In recognition of this likelihood, some ancillary analyses and planning are underway to determine how to mitigate the economic impacts of these changes. Some ideas include land fallowing, reverting land to winter rain-fed agriculture and ranching, solar energy installations, specific conversion to novel habitats that support wildlife, and seeking technology that can convert previously unusable but relatively widely available brackish groundwater sources to usable water.

To conclude, I mentioned SGMA is a journey. The law allows a term of 20 years from adoption of the sustainability plan to attain the goals. So, there is some time to make some adjustments and avoid the state assuming enforcement. But based on my career in water, 20 years goes by in the blink of an eye.   

Sargeant J. Green is a water management specialist with the Center for Irrigation Technology and California Water Institute at California State University, Fresno. He is also associate director of the Water Resources and Policy Initiatives program for the CSU chancellor’s office.
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