MISSION OF THE BASIN: Improve regional water supply reliability and protect groundwater-dependent ecosystems.
Steadfast effort in Northern California is yielding an integrated strategy to coordinate environmental outcomes and build a more resilient ecosystem.
The Freshwater Trust’s (TFT) analytics and scenario-planning tools are enabling conservation practitioners, resource agency managers, and producers to evaluate options to meet a variety of surface and groundwater objectives driven by state regulations. Actions to improve land management and water availability include irrigation efficiency upgrades, cover cropping, and aquifer recharge. Chief among these projects is Harvest Water, a $600-million recycled water project to provide agricultural water supply.
Harvest Water is the largest project of its kind in California. The region’s wastewater utility is implementing it in partnership with TFT. We are conducting outreach on agricultural land that will soon receive treated, recycled wastewater to offset groundwater pumping for irrigation and help preserve sensitive habitats for Sandhill cranes and other special- status species.
Elsewhere, we’ve helped implement one of the state’s first agricultural managed aquifer recharge (MAR) projects. This project uses corporate funds secured by TFT to deliver excess flood water from the Cosumnes River to adjacent vineyards, thereby recharging groundwater. In the Sacramento River, we have partnered with local landowners to keep more water instream, improving outcomes for native fish and wildlife. Lastly, we continue to support groundwater management efforts in the Sacramento-San Joaquin Delta, helping to ensure that these resources are sustainable for future generations.
Using Harvest Water as a starting point, TFT and its partners have developed a portfolio of strategic shovel-ready projects that will help produce benefits related to wildfire, flood, drought, habitat, and greenhouse gases. Our introduction of a “watershed outcomes bank” brings together multiple funding sources and directs the funds in a coordinated and trackable fashion to priority projects. As these initial projects attract further funding, they generate the momentum needed to achieve tangible watershed improvements.
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In 2015 California passed Senate Bill 88, which made it mandatory for those diverting more than 10 acre-feet of surface water per year to accurately measure the amount of water used. In most cases, SB 88 requires meters for surface water diversions. However, in the Northern Delta, it is technically and logistically challenging to meter the diversions. Instead, most people use gravity-fed siphons, which are unpowered pipes that bring water from the rivers that are at higher elevations to the farms on the Delta islands. TFT is a partner in a scientific consortium to find more accurate and cost-effective methods of measuring water use.
In many locations, groundwater mixes with water in a river channel through the porous sediment surrounding a river. This is a natural process called hyporheic exchange. Rivers recharge the groundwater and, in some cases, rivers are depleted by declining groundwater. While many streams can naturally "lose" water, it is particularly the over-pumping of groundwater in much of California that has led to stream flows being significantly depleted.
For example, in south Sacramento County, a drop in the groundwater table of 30 feet in one area has jeopardized multiple other surrounding water resources – from irrigation wells to wetlands and forests to rivers that support migrating salmon.
TFT is working on several initiatives related to groundwater sustainability in northern California. It is working with the Northern Delta Groundwater Sustainability Agency (NDGSA) and its 17 member agencies to provide administrative support, analytical services, and grant-writing assistance as the NDGSA prepares their Groundwater Sustainability Plans (GSPs).
On a broader scale, TFT is developing user-friendly tools that provide information about water savings, the costs to implement savings, and, most importantly, how to add more water through conservation practices such as cover cropping and winter recharge with surface and stormwater.
In lieu recharge is where surface water is used as a substitute for pumping from a groundwater source. The substituted water is a renewable supply, such as excess surface water or treated wastewater. In lieu recharge allows for "conjunctive use," where surface water is used by persons that could otherwise extract groundwater in order to leave groundwater in the basin. This practice can help improve water reliability in California.
Groundwater is important to everyone, from farmers growing crops to local communities that rely on groundwater as their source of drinking water. Therefore, regional Groundwater Sustainability Plans (GSPs) need to consider the needs and concerns of all water users. In eastern Solano County, TFT is working with local partners to reach out to disadvantaged communities (where incomes are less than 80% of the state’s median household income) to actively engage them in the decision-making process about the future of the resource.
