Innovative groundwater storage initiative receives millions in funding

On Tuesday, July 24, the California Water Commission approved a $280 million initiative to use recycled wastewater instead of groundwater on agricultural fields in Northern California.

Regional San, Sacramento’s regional wastewater utility, received this funding from Proposition 1, a voter-approved, $7.5 billion bond passed in 2014 to fund watershed protection and restoration, water supply infrastructure projects, and drinking water protection. Regional San has partnered with The Freshwater Trust (TFT) throughout the process of competing for this funding to plan, implement, and track the environmental benefits of this innovative conservation solution.

“Groundwater depletion has cut the river off from the groundwater that sustains its flows,” said Erik Ringelberg, California director with TFT. “Climate change, increased pressures from urbanization and more require that we think differently about how to replenish the groundwater that serves as critical reservoirs.”

In southern Sacramento County, a drop in the groundwater table of 30 feet has jeopardized a connected ecosystem—from irrigation wells to wetlands and forests to migrating fish. TFT has focused on surface water and groundwater improvements in this region by collaborating with landowners and irrigators since 2016.

“The loss of our aquifers has had profound impacts statewide,” said Ringelberg. “It’s a major reason why we’ve focused our efforts on groundwater since opening our first office in California two years ago. The impacts are especially felt here.”

The Cosumnes River supports the Stone Lakes National Wildlife Refuge, the Cosumnes Preserve and a network of private conservation lands. These areas rely on a water table that’s been compromised by heavy use and is expected to be further impacted by climate change.

“The thesis behind this project is that the recycled water will help reverse some of the impacts of the over-pumping on the Cosumnes River,” said Ringelberg. “It’s critical to track the improvements and impacts of this conservation investment over time.”

TFT supported Regional San in a year-long competition for water storage funds under Proposition 1, working with the Regional San team to identify the many environmental benefits of using recycled water to replace groundwater used in irrigated agriculture. Impacts from over-pumping the aquifer are rapidly reversed by substituting the region’s recycled water, protecting the nearby Cosumnes River and Stone Lakes National Wildlife Refuge.

The 15 state and federally listed species living in this area are protected not just from these current impacts, but from modeled climate change scenarios showing that without the project, these critical wetlands would be completely disconnected from the groundwater resource.

“TFT is proud to be a partner and support Regional San on this unique conservation effort using recycled water,” said Ringelberg. “This is a unique time for conservation in California. This funding will help us apply a basin-scale conservation approach to more than 10 square miles of habitat improvements in critical refugia.”

This substitution will reduce the need to pump groundwater for irrigation. The retained groundwater will interact with surface water, thereby restoring the region’s overall groundwater elevations and stream flows that support streamside and wetland vegetation.

Active streamside revegetation and invasive weed control are also part of the program. This combined approach will improve both the quality and quantity of riparian and wetland habitats that support a host of listed native species, including Chinook salmon and the giant garter snake.

“We are excited to move the South County Ag Program [now called Harvest Water] forward to the next phases of development and implementation,” said Terrie Mitchell, Regional San’s Manager of Legislative & Regulatory Affairs. “We take our commitment to environmental stewardship very seriously. Using recycled water for crop irrigation, in-lieu groundwater recharge, habitat restoration and other beneficial uses is key to help promote a more sustainable environment for future generations.”

Since 2016, TFT has focused on surface water and groundwater improvements in the Sacramento-San Joaquin Delta through collaborations with landowners and irrigators, agencies such as the Northern Delta Groundwater Sustainability Agency and Solano County Water Agency, funders such as federal and state Conservation Innovation Grants, and partners in innovative projects such as Regional San.

The main goal is to bring together actions governed by disparate state regulations—including SGMA, Senate Bill 88, and the Irrigated Lands Regulatory Program—into a cohesive, coordinated approach that achieves improvements in the basin.