Groundwater depletion is a big problem in parts of California. But it is not the only groundwater problem. The state also has many areas of polluted groundwater, and some places where groundwater overdraft has caused the land to subside, damaging roads, canals and other infrastructure. Near the coast, heavy groundwater pumping has caused contamination by pulling seawater underground from the ocean.

But if you wanted to obtain a permit from the state to manage these problems by recharging groundwater, you could be out of luck.

Groundwater recharge is not considered a “beneficial use” under California water law if all you want to do is manage pollution in an aquifer or control subsidence. To obtain a water right, you must have a plan to apply that water for an accepted beneficial purpose, such as growing crops or delivering drinking water.

This could become a problem as dozens of local agencies move to comply with the Sustainable Groundwater Management Act (SGMA), a state law adopted in 2014. The sustainability goals under this law include treating pollution, managing seawater intrusion and controlling land subsidence. And yet the state does not allow surface water – diverted from a river or stream – to be used for these groundwater recharge purposes.

“We want a broader suite of things from our water than we used to,” said Holly Doremus, a professor of water law at U.C. Berkeley. “The new thing encouraged by SGMA is the idea that you might want to put water in the ground not for the purpose of taking water out later, but for the purpose of making the aquifer healthier. We think that would often qualify as a beneficial use.”

Doremus is coauthor of a new report by a team of U.C. experts that examines this conundrum. They conclude that the State Water Resources Control Board needs to expand its definition of beneficial use to accommodate these other groundwater benefits.

A key issue is the difference between groundwater “recharge” and “storage.” The latter implies that the water will be pumped out later and reused – to grow food or refine into drinking water. Therefore, the path to obtaining a state permit to divert service water into an aquifer is clear for storage purposes.

Recharge, however, is a different matter. It implies the water will be diverted and pumped into the aquifer – and then left there, possibly forever. There can certainly be a benefit to this, such as diluting nitrate pollution caused by decades of fertilizer use on farms above ground. It’s just not recognized in the law.

“Clarifying that those SGMA purposes are ‘beneficial’ could be something we need to do,” said Jennifer Clary, California water programs manager at Clean Water Action, a nonprofit group. “Avoiding undesirable results on water quality is one of the requirements of SGMA. So I think saying yes on recharge water for this purpose is perfectly acceptable.”

Clearing up confusion around the issue is important, because groundwater agencies overseeing severely overdrafted basins face a 2020 deadline to submit management plans. Many of those plans will need to identify recharge projects.

For now, uncertainty may discourage some organizations from seeking a water right for recharge projects.

“This is a gray area,” said Andrew Fisher, a professor of hydrogeology at U.C. Santa Cruz. “I have found that landowners, tenants, agency staff and others are reluctant to pursue recharge projects that require permits for surface water use, if that use requires making a case independent from extractive use.”

There is even an open question as to whether achieving “sustainability” in an aquifer – as required under SGMA – would be considered a beneficial use. Restoring groundwater to some sustainable elevation in an aquifer would require the use of surface water for recharge. Presumably, once the sustainable elevation is reached, that water would stay in the aquifer forever and would not be applied to grow crops or sent to a treatment plant. Thus, it might not satisfy today’s narrow definition of the beneficial use requirement.

“It can be complicated to figure out what exactly have you put in and what exactly can you get out,” Doremus said. “The water board kind of needs to work some of this out and be a little bit clearer.”

She said a change in law is not required to create a broader definition of beneficial uses related to groundwater. The state water board can change the definition on its own at any time.

The board hasn’t done that yet. A page on its website states that preventing seawater intrusion may qualify as a beneficial use, but that’s as far as it goes. Application materials for non-storage water rights make no reference to groundwater uses that might be considered beneficial, and make no reference to SGMA.

Clary said many local agencies grappling with SGMA are afraid to deal with a water rights application because of the complexity involved – if they’re thinking about it at all. Taking uncertainty out of the process with a broader definition of beneficial use would be a good place to start, she said.

“A lot of folks haven’t figured out how complicated SGMA really is when it comes to water rights and allocations,” she said. “I think that’s really problematic.”

Officials at the state water board could not be reached for comment.

The legislature considered a bill earlier this year that would have defined groundwater recharge as a beneficial use.

The bill, A.B. 2649 by Assemblymember Joaquin Arambula (D-Fresno), also would have eliminated – for the purposes of groundwater recharge – a long-standing requirement that water rights be put to a beneficial use within a five-year period or be forfeited. This would have opened the door to more non-extractive groundwater recharge projects – such as subsidence reversal – in which the water might never be pumped out.

The bill was approved in the Assembly, but stalled before a companion bill emerged in the Senate.

Doremus said the bill might have gone too far by making a blanket statement that all groundwater recharge is beneficial. That isn’t always the case: Not all water pumped underground stays there, she said, nor does it necessarily go where you want it to go. It could meander to an adjoining aquifer where the benefits – diluting water pollution, for example – might disappear.

A formal water-right application process should still be required, she said, in which the applicant must specify the beneficial use that is intended and provide evidence of real benefits to the aquifer.

Clary agrees.

“If you create a beneficial use for recharge in and of itself, then you’re competing with other things you might think are important, like drinking water or fish in the stream,” she said. “When you recharge groundwater, you need to recharge it for a reason.”