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Time's Up on Groundwater Plans: One of the Most Important New California Water Laws in 50 Years Explained

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A groundwater pump operates in Kern County. (Craig Miller/KQED)

Much of California’s water supply is a hidden asset: Deep below the surface, rocks, gravel and sand store water like a sponge, in an underground zone called an aquifer. 

In dry years, this groundwater has been tapped to save farms, keep grass green and provide drinking water to millions of Californians. But over time, people have taken more water out than nature has put back in. Estimates vary, but according to the U.S. Geological Survey, California pumped 41 trillion gallons of water fom the ground in about 100 years, through 2013. In some parts of the Central Valley, that means land has been dropping around a foot a year

The landmark Sustainable Groundwater Management Act, or SGMA, requires some of the state’s thirstiest areas form local “Groundwater Sustainability Agencies” and submit long-term plans by Jan. 31 for keeping aquifers healthy. Together, those plans will add up to a big reveal, as groundwater managers finally disclose how badly they believe their aquifers are overdrawn, and a collective picture emerges. It’s a major shift and arguably the most important new California water law in 50 years.

Here are some key things to know about the groundwater situation in California and how the law will impact the state. 

Until six years ago, California did not routinely regulate or monitor groundwater. 

The California Constitution decrees that water use has to be reasonable and beneficial, but the state has placed few limits on how water can be pumped from the ground. A 1914 law empowering the state water board to manage the resource omitted groundwater. You can blame the lack of regulation partly on 18th-century Spanish colonists who brought with them the idea that a landowner is entitled to all of the water below the surface, without any obligation to share it. 

At the beginning of the 20th century, water was still plentiful in California, and the idea of unfettered access to groundwater made sense in a state lush with wetlands. 

So for the last century, landowners continued to think of groundwater as pretty much a birthright. It’s become an essential component of California’s water portfolio: State officials say 30 million residents rely on groundwater for at least some portion of their drinking supply, and in the driest years, people keep basically sticking a straw into the earth to slake their thirst. 


Water at the surface is connected to the water hidden below. 

The water from California’s rivers and streams, along with rainwater, seeps into the ground, where it remains among the rocks, gravel and sand. Between these surface and sub-surface supplies lies the water table, which is what hydrologists call the top of the area that has been saturated underground. 

Using too much groundwater affects not only surface water supplies but also entire ecosystems. Pumping from the earth deep enough to suck water out can lower the groundwater table and dry out surface soils. 

Rivers and streams feed more than 500 aquifers around California. Less than a quarter of these account for the overwhelming majority of groundwater pumping. 

In these basins, this landmark law already has begun to transform the Central Valley. 

For decades, farmers fought the regulation and monitoring of groundwater tooth and nail. Now that it’s here, SGMA has already begun to change the region’s economy and landscape, as some farmers have sold or fallowed land in antipation of the coming changes.

The Public Policy Institute of California predicts that agricultural interests may have to let 750,000 acres of land go fallow, mostly in parts of the San Joaquin Valley where the most severe overpumping has occurred.

Farmers may also have to cycle current crops out for those requiring less water. For example, almonds are water-intensive but have been profitable in recent years; those margins would change if water becomes much  more expensive than it is now. 

Some local water managers have a lot of work to show by the end of the month. 

There are 21 “critically overdrafted” basins for which officials must submit groundwater management plans by Jan. 31. 

In each area where people have habitually pumped more than has come back in, local water managers have to figure out how much they’ve taken from underground, and how water at the surface replenishes those stores. Each region has to propose ways to monitor groundwater over multiple intervals: day-to-day, short-term, seasonal, and yearslong. Basically, they’re creating monitoring systems, in some cases from scratch, to help determine whether conditions are changing. 

The groundwater plans are built around models for how to share water in a way that’s sustainable by 2040. Each one can be a little different, but local managers and the state have to check up on every single one and meet interim deadlines every five years. 

The Department of Water Resources can accept the plans as is or ask for tweaks. DWR can also refer the plans to the state water board for intervention, meaning that local officials may have to try again if the state judges a plan unlikely to succeed. In extreme cases, the state may have to step in to settle disputes over local rights.

This isn’t just a Valley problem.

Balancing aquifers like bank accounts will cost money and effort in the Bay Area and other parts of the state. Two years from now, managers for dozens more groundwater basins with state-designated risk ratings of high or medium must submit their own plans to the State Water Resources Control Board. They include water managers in Sonoma, Napa, San Mateo and Santa Clara counties. 

Even though these plans will take years to come into focus, plenty of political decisions remain.

State requirements for sustainable regional groundwater management haven’t taken away anyone’s rights; the rules have changed how localities must meet their water needs from now on. Even the plans submitted by the locally formed groundwater agencies that will meet this year’s deadline haven’t absolutely nailed down who gets to use what in the future. The coming decisions and politics about water may be tense, but the alternative is that one day, wells could run dry.


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