- Many groundwater targets vary widely across local agencies.
- Up to 60–70% of wells may miss 2040 goals under higher use.
- Even cutting water use in half may not meet many targets.
- Long-term declines could leave most wells below goals by 2070.
Tuesday, April 28, 2026 — In 2014, California passed the Sustainable Groundwater Management Act, called SGMA. The law was designed to stop decades of over-pumping and protect underground water supplies for the future.
Under this law, local agencies were required to create plans to bring groundwater use into balance. These plans set specific water level goals that must be reached by 2040 and maintained through 2070.
A new study
first published April 21, 2026, takes a close look at those goals. It asks a simple but important question: are they realistic?
Why Groundwater Matters So Much.
Groundwater is not a backup supply in California. It is a lifeline.
On average, it provides about 40 percent of the state’s water. During drought, that number can rise to 60 percent.
In the Central Valley, this water supports one of the most productive farming regions in the world. That region generates roughly $60 billion each year in agricultural income.
But there is a problem. Decades of heavy pumping have drained many aquifers faster than they can refill.
A Patchwork of Goals Across the Valley.
The study found that groundwater targets are not consistent.
Local agencies set their own goals. As a result, some areas aim to raise water levels above where they were in 2020. Others allow levels to drop much lower.
In some cases, neighboring regions have very different targets, even though they share the same underground water system.
This creates a patchwork approach across a single connected aquifer.
What the Models Show About the Future.
Researchers used a large regional groundwater model to test what might happen under different scenarios.
The results are sobering.
- If groundwater use increases, about 60 to 70 percent of wells may fail to meet their 2040 goals.
- Even if groundwater demand is cut in half, nearly 40 percent of wells could still fall short.
- Under baseline conditions, about half of wells may miss their targets by 2040.
The long-term outlook is even more concerning.
By 2070, the study found that up to 70 percent of wells could fail to meet their goals due to ongoing groundwater declines.
Why Cutting Use Alone May Not Be Enough.
One of the most striking findings is that reducing pumping does help, but not always enough.
Even large reductions in water use may not allow groundwater levels to recover quickly enough to meet certain targets.
This happens for several reasons:
- Some areas set aggressive recovery goals.
- Water demand remains high due to farming and population needs.
- Aquifers recover slowly, especially after long periods of decline.
In simple terms, the system takes time to heal.
A Connected System With Shared Consequences.
Groundwater does not follow political boundaries.
Water pumped in one area can affect levels miles away. The study highlights how actions in one region can impact neighboring areas.
This creates challenges for local agencies that are trying to meet their own targets while sharing the same aquifer.
Climate Pressures Add Another Layer.
The study also tested how climate changes could affect groundwater.
The results show that rising evaporation rates may have a stronger impact than changes in rainfall.
Higher evaporation increases water demand from crops, which leads to more pumping. That, in turn, lowers groundwater levels further.
Gaps in Monitoring.
The research also found that some areas lack enough monitoring wells.
This means groundwater declines could be happening in places that are not being tracked closely.
In certain regions, actual declines may be greater than what current data shows.
What the Study Suggests Moving Forward.
The study does not make policy decisions. It focuses on the data.
But it does point to a key challenge.
Many current groundwater goals may be difficult to reach under existing conditions. Even strong conservation efforts may not fully close the gap.
Researchers note that additional actions, such as increased recharge or more coordinated management, may help improve outcomes.
A Long Road to Sustainability.
California’s groundwater law set a clear deadline. By 2040, aquifers should be stable.
This study suggests that reaching that goal may be harder than expected.
The findings highlight the complexity of managing a shared resource that has been under pressure for decades.
The path forward will likely require continued adjustments as conditions change and more data becomes available.
Citation.
Platt, L. C., Weingarten, M., Faunt, C. C., Traum, J. A., & Boyce, S. E. (2026). Modeling future groundwater depletion to evaluate sustainability goals set under the sustainable groundwater management act in the critically overdrafted basins of the Central Valley, California, USA (2020–2070). Water Resources Research, 62, e2025WR040639. https://doi.org/10.1029/2025WR040639
