The Sacramento-San Joaquin

The Problem We Are Solving

Parched rivers, subsiding aquifers and a dry Mediterranean climate have provided California the opportunity to consider new approaches for integrated water resource management. Challenges around groundwater sustainability, surface water management and irrigation efficiencies all overlap geographically in the state’s northern Sacramento River Watershed. This watershed is the source of 31% of California’s total surface water runoff.

All of these concerns overlap geographically in the Sacramento-San Joaquin River basin. The Freshwater Trust is currently working in three geographies within the basin.

Northern Delta:

The Northern Delta is an area rich with natural resources and a history that includes more than a century of sustainable farming and wildlife stewardship. Much of this area was transferred from federal land to California in 1850 as a part of the Swamp and Overflow Act, where it was reclaimed for agriculture. This region has ample, naturally high water tables, which results in groundwater near the surface. It has an extensive levee system, which conveys surface water to local crops and drinking water as far as the San Francisco Bay Area. 

Solano Subbasin:

The Solano Subbasin (part of the Sacramento Valley Groundwater Basin) covers the eastern half of Solano County and extends into the Northern Delta. It is the primary source of groundwater used for municipal, agricultural and domestic supply in Solano County.

South American and Cosumnes Subbasins: 

The South American Subbasin is bounded on the west by the Sacramento River, on the north by the American River, and on the south by the Cosumnes and Mokelumne Rivers. These perennial rivers interact strongly with groundwater in the basin. The Cosumnes River, southeast of Sacramento, begins in the Sierra Nevada Mountains and empties into the Sacramento-San Joaquin Delta. The Cosumnes Subbasin contains rich agricultural lands as well as some of the largest remaining wetlands and riparian areas in the Central Valley.

How We Are Solving It

In 2018, we doubled the number of staff working in this watershed and began setting the stage for scaling up program implementation. Time is of the essence for many local farmers and irrigators who comprise the recently formed groundwater sustainability agencies that have to complete sustainability plans by 2020 or 2022.

We’ve built firm relationships with stakeholders that represent more than 30,000 acres of surface water irrigated land and 70,000 acres of groundwater-dependent land across the Northern Delta. We’re analyzing conservation practices for more than 40 crop types across 180,000 acres in Solano Subbasin. We’re also working with agricultural partners, nonprofits and vulnerable communities to identify integrated approaches to protect shallow groundwater that support critical ecosystems as well as drinking water and irrigation water.

Our partnership with the Sacramento Regional County Sanitation District, built in part on TFT’s quantified conservation approach, secured $280.5 million in state funds to use recycled wastewater instead of groundwater on agricultural fields. By reducing the need to pump groundwater, unique habitats in the basin will benefit, including wetlands, vernal pools, streamside forests and the groundwater-connected Cosumnes River. These areas support listed native species, including fall-run Chinook salmon, sandhill cranes and giant garter snakes.

Additionally, we kicked off a collaboration to pilot technologies to track groundwater use in one of the largest and most at-risk aquifers in North America. Our project uses remote Internet of things (IoT) sensors to measure and transmit real-time water extraction data to a blockchain-enabled platform.

We are working with dedicated partners committed to the same goal we are – the resilience of water resources. And we’re excited to pilot new technologies and methods with them. It’s a critical step in scaling up solutions quickly, so that we can apply them across the state.

‒  Becky Rittenburg, Conservation Programs Manager

Irrigated farmland in northern California available to migratory birds

The blockchain project moved into implementation in 2019, with sensors installed at 10 sites and, over the next year, more than 20 sites could be up and running. Recruitment of landowners for the Regional San recycled water project will ramp up as well in 2019.

Want to help The Freshwater Trust and the Sacramento-San Joaquin River Basin Partners keep working on the Sacramento-San Joaquin? Make a gift today.

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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.