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Connect the Drops

The Best Options for Groundwater Recharge

The water bond passed by voters in 2014 provides funding for projects to help recharge groundwater. But some of the best and most cost-effective options may be smaller-scale projects. Here’s a look at some promising ones in both urban and agricultural areas.

Written by Kirsten James Published on Read time Approx. 4 minutes

Don’t let El Niño’s heavy rain and snow lull you into thinking the drought is over. As of early March, the state has received just 68 percent of an average year’s rainfall.

Despite that shortfall, California can do much more with the water it has. Particularly during relatively heavy rainfall years like this one, the state can recharge the groundwater supplies and store that water in the ground to help keep the state’s rural and urban areas afloat through dry years.

Typically, 30 percent of California’s water supply comes from groundwater. But as we enter our fifth year of drought, that number is significantly higher, with 60 percent or more of our water supply coming from groundwater. That’s far more than the season’s rainfall and snowpack can replenish.

There are many ways we can recharge our groundwater supplies, and provisions in the Proposition 1 water bond passed in 2014 provide a unique opportunity to fund them. Now, the California Water Commission (CWC) has released the first of two related draft regulations that specify how to assess project proposals and allocate $2.7 billion in funds intended to improve the state’s water storage.

While the bond measure requires projects to provide a public benefit, be cost-effective and improve water quality, the complexity of the draft regulations may mean that only larger-scale, big-budget projects will be able to navigate the process and receive funding. That’s a shame, because smaller-scale options can be just as effective and even cost the state less.

Let’s start with urban groundwater-recharge projects. In Los Angeles, 79 of the 228 community water systems are 100 percent reliant on groundwater. And while stormwater runoff has long been considered part of the problem – because water flowing over paved areas can lead to flooding and can also pick up toxic chemicals that pollute and harm human health – it is now becoming part of the solution.

For example, the L.A. Department of Water and Power’s (LADWP) comprehensive stormwater capture plan includes an innovative, integrated project in Strathern Park that will capture as much as 1,500 acre-feet (1.9 million cubic meters) of water per year of stormwater runoff, reducing flooding as well as the region’s need for water imports. LADWP estimates that if the city maximized its stormwater capture potential, it could realize an additional 200,000 acre-feet of water, or nearly a third of its annual water use.

Community stormwater capture and recharge projects deserve water bond funding. While a larger agency such as LADWP may have the staff expertise to apply for funding from the CWC, smaller water agencies and municipalities may have trouble navigating the complex rules.

Moving to rural areas, the state’s farm belt has tremendous need for replenishing groundwater supplies. Dedicated recharge basins, areas that are set aside for recharge, provide flood protection and groundwater recharge, but require big swaths of land that sit idle when not filled with water, explained Kelli McCune, senior project manager at Sustainable Conservation, at a recent forum on groundwater recharge solutions hosted by Ceres.

Smaller-scale alternatives may be preferable in some cases. Sustainable Conservation, for example, worked with researchers and Don Cameron from Terranova Ranch, southwest of Fresno, to replenish his groundwater supplies by allowing floodwaters to recharge active croplands.

“In 2011, the last wet year, Cameron’s grapevines, pistachio orchards and fallow land were able to recharge 3,000 acre-feet of groundwater,” McCune said, “enough to fill nearly 1,500 Olympic-sized swimming pools, while suffering no crop loss.”

Two big questions about onfarm recharge include the cost of these projects and whether farmlands would impact groundwater quality. Sustainable Conservation has found, however, that the cost of onfarm recharge is lower than dedicated recharge basins and potentially a magnitude lower than surface storage projects: With costs spread over 100 years, onfarm recharge costs between $63 and $168 per acre-foot of water, while a dedicated recharge basin costs $218 per acre-foot. Surface storage projects can cost $1,900 or more per acre-foot.

Moreover, McCune said that the floodwaters for the Terranova project were clean Sierra Nevada snowmelt and direct rainfall, which diluted the groundwater and improved its quality.

Nick Blom, a Modesto-area almond farmer and board member for the Modesto Irrigation District, who also participated in the forum, conducted an onfarm recharge project this January in partnership with the Almond Board and U.C. Davis to test flooding’s effects on trees and groundwater quality.

“It’s a little premature to say if it’s working or not, but so far we haven’t seen any detriment to my orchard,” Blom said. “Most trees and vines are dormant now, so you can do a recharge like this and not hinder the root development.”

Projects like these in Modesto, Fresno and Los Angeles suggest a promising way forward for water-stressed California, but whether they can be replicated in other areas will depend on how the CWC spends the water bond funds.

In order to help innovative, smart, cost-effective recharge projects get the consideration they deserve, Ceres and Connect the Drops business partners, Clif Bar, the Coca-Cola Company, Dignity Health, Fetzer Vineyards, General Mills, Sierra Nevada Brewing Company, Symantec and the North Face submitted a letter urging the CWC to create mechanisms that allow for equal consideration of smaller-scale groundwater recharge projects to make a big difference in California’s water use.

The public hearing for these regulations takes place on March 16. Hopefully the CWC will hear the call of a diverse group of stakeholders and ensure that groundwater recharge projects aren’t passed over.


Top image: Pedestrians cover up from heavy El Niño rains in downtown Los Angeles, Wednesday, January 6, 2016. L.A. has developed a new stormwater capture plan to harness 1,500 acre-feet of water a year that would normally run off city streets. (Richard Vogel, Associated Press)

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