Groundwater Recharge

 

A Useful Approach Only When There Are Clear Rules for Public Benefit

California’s water establishment – agribusiness, water districts, the state Department of Water Resources, and the think tanks, engineering firms, and consultants that support them – have been pushing groundwater recharge as a solution to the increasing hydrologic extremes driven by climate change. They argue if we store more water underground in wet years it will help enhance supply during the dry years.

As a concept it sounds good. However, a closer analysis shows that it could be beneficial or harmful, depending on the rules that apply. We must understand who pays, who benefits, and who decides to determine whether groundwater recharge projects benefit communities and the environment or whether they continue to subsidize harmful agricultural practices.

Why the current approach is harmful:

Presently, groundwater recharge projects fall into two categories: (1) Permitted projects that have undergone environmental review and have clear rules; and (2) A free-for-all authorized by Executive Orders that waive environmental protections and oversight. There are multiple problems with the second category. First, there are no limits on how much water is taken out of the rivers and how the water will be used when it is pumped back up from an aquifer. Second, there is no guarantee that such withdrawals will provide any public or environmental benefits. Additionally, there is the potential that they exacerbate harms to communities and the environment.

Take, for example, an agricultural irrigation district that can divert water from rivers to land where it can percolate into the ground. During a declared flood flow event, the district could take as much water as possible, regardless of how much other water districts are taking and with no regard for any flood mitigation efforts undertaken by government agencies. Afterward, the district could claim the right to pump more groundwater owing to its recharge action. The additional pumping could further impact communities reliant on shallow drinking water wells. Moreover, if the pumped water is used for permanent crops like nut trees, it would increase overall water demand, which would impact people fish, and wildlife in drier years when surface water supplies are scarce and groundwater levels drop.

Some groundwater sustainability agencies (GSAs), which are mainly controlled by the largest water users[1], have claimed that the ability to recharge during large storms means that they should be subject to fewer pumping restrictions under the state’s Sustainable Groundwater Management Act (SGMA).[2] These GSAs want the state to ignore the excess pumping that caused critical overdraft based on their intent to maximize groundwater recharge.

Another risk exists in areas where groundwater levels are currently adequate. Much of the Sacramento Valley has relatively stable groundwater levels due to senior water rights on the Sacramento River. However, the potential for surface water supply reductions to meet environmental goals is making groundwater pumping more appealing. In addition, storing water underground requires available storage space, which creates another incentive for increased pumping. This pumping could create harm to fish and wildlife due to the interconnected nature of surface water and groundwater. Essentially, in many locations pumping groundwater reduces surface water flows. Allowing for unregulated diversion of flood flows for groundwater recharge makes harmful levels of groundwater pumping more likely.

Why the narrative that the Delta Tunnel will support groundwater recharge is false:

The Governor and other proponents of the Delta Conveyance Project (DCP or Delta Tunnel) believe that the DCP will enhance groundwater recharge.[3] However, the claim lacks evidence, especially given the uncertainties around the DCP’s eventual operations. Moreover, even if the DCP could deliver more water to some areas for groundwater recharge, it would not be cost-effective and there is no guarantee that any stored groundwater would be allocated equitably. In Southern California, which receives over 2/3 of SWP deliveries, the available groundwater basins are in the desert far from population centers.[4] Diverting more water to those aquifers does nothing to ensure more reliable supplies for coastal cities. Furthermore, the current cost estimate for DCP construction is over $20 billion. If the Delta Tunnel is ever built, it could end up costing far more, raising consumer rates to levels that further reduce demand and the need for additional water storage during droughts.

The one area the DCP could enable significant additional groundwater storage is in Kern County, where most of the water is used for agriculture. Thus, Kern County agribusiness, which controls the Kern Water Bank, would be the beneficiary of a massive public investment financed almost exclusively by urban ratepayers. This inequity demonstrates how the groundwater recharge narrative is very misleading, and why the issues of cost, benefit, and allocation matter.

Identifying the rules that are necessary for fair and equitable groundwater recharge:

Groundwater recharge projects should be designed to achieve public and environmental benefits. Public needs, including drinking water well access, urban water supply, and environmental needs for rivers and streams must be met before any recharge is allowed for private use. Furthermore, recharge projects integrated as part of overall groundwater management must be subject to equitable governance, meaning that tribes, community members, and organizations dedicated to the protection of fish and wildlife need full representation on water supply and groundwater sustainability agencies.

Monitoring and enforcement are also critical to effective and equitable recharge projects. There should be limits on water diversions for recharge, prohibitions on waivers of environmental requirements such as flood planning, and documented compliance with SGMA before any recharge projects are evaluated. Creating these guardrails requires strengthening SGMA and regulations promulgated by the State Water Board.

Sidebar

Sound groundwater recharge policy requires proper review, permitting and monitoring:

Groundwater recharge is justifiable when subject to rigorous oversight and integrated into a broader and effective water management system. The City of Roseville’s groundwater program is an exemplary example of such an approach.

Roseville’s primary water source is Folsom Lake, a reservoir that was drawn down to critical levels during the 2015 drought. In response, Roseville employed aquifer storage and recovery technology to inject water into underlying aquifers during flood flows for later extraction.

The city conducted a full environmental review of the project prior to implementation. Because water is only taken during flood events and is closely monitored, the risk to fisheries, wildlife and other ecosystem values is minimal. Roseville considers groundwater an augmentation to its water supplies rather than a primary source, with the emphasis on operational flexibility and sustainability.

 
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