Recharge water flows through this pipe into a planted field at Terranova as part of this groundwater recharge system designed to divert floodwater from the Kings River for groundwater storage in Fresno County. Photo by Andrew Innerarity / DWR

NOTEBOOK FEATURE: Water rights key to San Joaquin Valley aquifer recharge

Written by Robin Meadows

It sounds like such a simple fix for California’s groundwater woes. In phenomenally wet years like this one, when reservoirs are so full water is still being released to make room for snowmelt, just use some of that liquid wealth to inundate agricultural lands above severely overdrafted aquifers.

This groundwater recharge project’s headgates are seen near the bridge on a bank of the Kings River in this photograph taken via drone. The system is designed to move floodwater diverted from the river to areas of Terranova Ranch and capture excess flow for groundwater storage in Fresno County. Andrew Innerarity / DWR

But nothing is simple in the world of California water. This approach, called managed aquifer recharge, has a host of complications including sorting out who has rights to floodwaters, how to allocate those rights equitably, and whether plans for securing those rights for recharge are realistic.

The need for managed aquifer recharge is great. Worst off is the San Joaquin Valley, where a century of overpumping to irrigate agriculture has left nearly all the groundwater basins critically overdrafted. A groundwater basin is made of stacks of aquifers, which store water underground in the spaces between layer upon layer of sand, soil, and gravel.

“We’ve been living beyond our means,” says Michael Kiparsky, Director of the Wheeler Water Institute at the UC Berkeley School of Law. “It’s easy to take water out much faster than it naturally replenishes.”

Under the 2014 Sustainable Groundwater Management Act (SGMA), basins must be brought back into balance by 2042. California’s groundwater basins have the capacity to store 17 times more water than all the state’s major reservoirs combined, at 850 million versus 50 million acre-feet. An acre-foot of water is about 326,000 gallons, enough to irrigate about a third of an acre of most crops for a year or to supply nearly three households for a year.


“Pretty much all of the surface water in California is spoken for already, but high flows from massive winter storms are seen as a new supply and that’s a really rare thing,” Kiparsky says. “There’s a lot of interest by the state in using them for managed aquifer recharge, which is easier to focus on than reducing extraction—it’s politically expedient.”

Water released from Lake Oroville in anticipation of snowmelt. Photo by Ken James-DWR.

The question is: who can use these high flows? “People just want to grab it because it’s there now,” says Dave Owen, an environmental law expert at UC College of the Law, San Francisco. “But you can’t divert surface water without a right, and we have a legal process that’s designed to be careful—we’re not in a position to turn on a dime.”

To get a water right, users need a permit from the State Water Resources Control Board, which must account for the needs of other users—and ecosystems. “We’re learning that floods have environmental value,” Owen points out. “These flows are not all wasted.”

High flows flush out water pollutants and carry sediment down waterways, sustaining tidal marshes, mudflats, and beaches, explains U.S. Geological Survey Scientist Emeritus Jim Cloern in a 2017 Public Policy Institute of California blog post called “The Myth of Water Wasted to the Sea.”

Moreover, salmon in California depend on high flows. “Basically, wet years are the only thing keeping salmon around,” says UC Davis fish expert Andrew Rypel. “We need to be careful about marginally high flow years and how we use that water.”


Getting a 180-day permit to capture high flows takes several months, and getting a 5-year permit can take 12 months. The Water Board has issued 28 high flow permits since 2016.

Fresno County almond field inundated with floodwater diverted from the Kings River for a groundwater recharge project. Photo by Andrew Innerarity-DWR.

Owen anticipates that the board will likely expedite this process by, for example, offering explicit guidelines for what it needs to see in permit applications as well as what will sink an application. He also notes that applicants could secure permits well in advance instead of waiting until a deluge is already underway. “I think we can solve this problem over time,” Owen says.

This year, Governor Gavin Newsom issued an executive order to speed permits for groundwater recharge by suspending environmental protections. UC Berkeley’s Kiparsky understands the frustration over not being able to seize fleeting high flows: “Millions of acre-feet of water went past fields that could be parched in future summers.”

But he hopes this year’s approach doesn’t become the norm. “There’s a real urgency to address the problem but there aren’t any easy answers here,” Kiparsky continues. “Just saying ‘go for it’ leads to a tremendous distortion.” Under California’s current system, rights to surface water are permitted largely according to whoever’s ancestors got to it first, leaving many—including tribes and fish—high and dry.

“The water rights system we have is not one anybody would design today,” Kiparsky concludes. “Do we want to recreate it or do we want to do a better job?”


Another challenge is that expediting permits to bank high flows underground won’t solve the San Joaquin Valley’s overdraft troubles. The region is so deep into water debt that, in the big picture, its high winter flows amount to just a drop in the bucket. Most water in the San Joaquin Valley comes from snowmelt in the southern Sierra Nevada, where snowpacks are typically smaller than those in the northern part of the mountain range.

A drone view of the James Irrigation District utilizing pumps from DWR’s Emergency Pump Program to divert water and fill a basin for groundwater recharge in Fresno County, California. Jonathan Wong / DWR

“Anybody who thinks groundwater recharge is going to ride to the rescue is expecting too much,” Owen says. “Even if we do everything right, we’re still going to have a huge imbalance in the San Joaquin Valley.”

Importing high flows from the Delta to the San Joaquin Valley would help but still wouldn’t be enough for the basin recovery mandated by SGMA, according to a 2020 study led by environmental engineer Sarfaraz Alam, who did this work while at UCLA and is now at Stanford.

The researchers found that managed aquifer recharge would contribute less than 8% of overdraft recovery in San Joaquin Basin, which stretches from Stockton to Fresno, and only about 3% in the Tulare Basin, which stretches from Fresno to Bakersfield. Water imports from the north would only bring those numbers to 30% and 62%, respectively.

“I’m excited about groundwater recharge—it’s a great alternative to surface storage,” Owen says. “But we need to be realistic: wet years don’t come along all the time.”


This indisputable fact of water life in California underscores the need to make the most of high winter flows that are available for groundwater recharge. Nicola Ulibarri, an environmental policy expert at UC Irvine, led a 2021 study on the feasibility of groundwater recharge plans submitted to the state.

Recharge water flows through this pipe into a planted field at Terranova as part of this groundwater recharge system designed to divert floodwater from the Kings River for groundwater storage in Fresno County. Photo by Andrew Innerarity / DWR

“Water rights is one of the constraining features,” Ulibarri says. “We looked at where they were getting their water and if they had existing rights—very few projects had that.” Of the 233 managed aquifer recharge project proposals, only 58 stated that they had an existing right to the water they planned to use.

“It’s a big red flag,” Ulibarri says.

Another red flag is that in the Tulare Basin, which is the most overdrafted and has the least water available for recharge, groundwater sustainability agency (GSA) plans failed to account for each others’ use.

“They are all basically proposing to do managed aquifer recharge with the same water,” Ulibarri says. “There’s a big need for regional coordination that takes the total acre-feet available and identifies the projects that make the most sense for basin recharge, not just which GSAs have the staff and funding to get a proposal together and build it.”

Ulibarri also points to planning as an end in itself, a practice she and colleagues documented in the California water world in a 2022 study. “Politically, it’s easy to require a plan and it makes it seem like they’re doing something,” she says. “There’s this assumption that SGMA solved the groundwater problem but I think it just delayed doing something.”

“A colleague likes to say that all policy is implementation,” Ulibarri continues. “What really matters is did it actually get done?”

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