The Yuba River and the Bay Delta: From Source to Sea — The Journey of Yuba Water to the Golden Gate

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The Golden Gate Bridge is a critical landmark for the migration of salmon in the region. Salmon are anadromous—they start their lives in freshwater, journey to the ocean, and then make their way back to freshwater to reproduce. The Golden Gate Bridge serves as the gateway and departure point for these fish as they navigate between the Pacific Ocean and the Yuba River, where they spawn. 

Under this iconic bridge is the original “Golden Gate”—a 1-mile wide and 3-mile-long strait that connects the Bay to the ocean.  Think of this as the finish line in a Yuba salmon’s 110-mile odyssey to the sea.  Two-thirds of California’s salmon pass through the Golden Gate

The Yuba to the Delta 

Much of the water that flows down the Yuba and into Sacramento never actually reaches the Golden Gate.  This fact is significant in that science shows the largest stressor on salmon is water flow. 

On average, 2.3 million acre-feet (the amount of water to cover a one-acre area one foot deep: 325,850 gallons) of water flows down the Yuba every year. The Yuba then flows into the Feather and Sacramento Rivers, comprising about one-third of the flow in the Feather and about 10 percent in the Sacramento.  According to the Public Policy Institute of California, the Sacramento River Basin accounts for over 30% of our state’s water supply.   

A significant portion of this water is diverted before it reaches the Delta. Much of it is redirected for crop irrigation, diverted by the State Water Project (SWP) and the federal Central Valley Project (CVP) pumps for irrigation and municipal needs in the San Francisco Bay Area, San Joaquin Valley, and Southern California. The remaining water makes its way to the Pacific Ocean via the Golden Gate. 

Less water — Less Salmon 

But climate change and other factors have changed how much water is available, increasing the strain on already stressed environmental systems. In 2021, more than 80% of the Sacramento and San Joaquin watersheds’ flow was diverted for other uses, leaving less water flowing into the Delta.

That decrease can have direct impacts on salmon. When the volume of water from the Sacramento River entering the Delta falls short of 40,000 to 50,000 acre-feet during the late winter and spring seasons, a critical period when the winter, spring, and fall salmon migrations occur, the sustainability of these salmon runs is severely compromised.   

The environment that comprises the Delta is also severely impacted. A lack of fresh water combined with an extensive network of levees means the Delta has witnessed a staggering loss of over 98% of its once-thriving wetlands, and about half of its vital freshwater supply has disappeared. This massive reduction has dealt a severe blow to the food sources and habitats of countless native flora and fauna. Moreover, the transformation and decline of the Delta has inadvertently rolled out the red carpet for a host of invasive species, including harmful algae blooms. Additionally, higher salinity levels in the water impacts local agriculture and water quality.  

“Poor management of Central Valley tributary rivers, including construction and operation of hundreds of dams and thousands of water diversions, has slashed annual freshwater flow into the Bay by 53% — and by more than 70% in the critical winter-spring period in some recent years. This massive overuse of limited freshwater resources — largely by industrial agribusiness — results in perpetual, man-made, drought-like conditions for native fish, which degrades their habitat.”

Center for Biological Diversity

For the Delta and salmon to survive, flows need to reach not only the Delta, but flow to the Golden Gate. 

Follow the Money – Follow the Water 

In accordance with the Reclamation Act of 1902 and several other statutes, the U.S. Bureau of Reclamation was granted Congressional approval to build and oversee a series of water projects. The objective was to “reclaim” the landscape of the Central Valley and foster a strong economy based on agriculture. 

Developed in 1933, the CVP holds approximately 13 million acre-feet of water within its 20 reservoirs in the northern part of California. Each year, the project moves 7.4 million acre-feet of water through its network of canals, with about 5 million acre-feet of that used to irrigate 3,000,000 acres of agricultural land in the Central Valley—making it the largest single-source of irrigation water in the state.   

MAP: Luedeling, Eike & Zhang, Minghua & Girvetz, Evan. (2009). Climatic Changes Lead to Declining Winter Chill for Fruit and Nut Trees in California during 1950–2099. PloS one. 4. e6166. 10.1371/journal.pone.0006166.

The State Water Project’s (SWP) development kicked off in 1957 amidst substantial resistance. Like the CVP, the goal was to move water from water-rich areas of Northern California to other parts of the state. Residents of Northern California were apprehensive about relinquishing their water rights, while those in the South sought assurances for water availability and cost stability. Nevertheless, the project moved forward, primarily propelled by the sway of affluent stakeholders in the south. Today, the SWP delivers drinking water to millions of Californians.  About 30% of its deliveries are to agriculture. 

Approximately 75% of California’s irrigated land is in the once-arid Central Valley. The irrigated lands in the Valley now total about 7 million acres – a land mass equal to the size of Connecticut. Because of the climate, the Central Valley’s farming practices require large amounts of water. Yet water is increasingly scarce due to reduced precipitation, groundwater depletion, and higher temperatures due to climate change.  

The Delta is the Heart of the CVP and SWP 

The central hub for these two projects is the Delta.  Each project has a pumping plant that diverts water out of the Delta and into an aqueduct or pipeline that brings it to the Central Valley or Southern California.   

The Harvey O. Banks Pumping Plant (Banks) serves the State Water Project (SWP) and the C.W. “Bill” Jones Pumping Plant (Jones) is used by the Central Valley Project (CVP).   

Harvey O. Banks Pumping Plant (from Delta Conveyance (ca.gov))

The amount of water pumped out of the Delta each year varies, but in 2019, the combined total was approximately 5.7 million acre-feet of water.  That’s about one-quarter of the water that actually flows into the Delta. 

The system of reservoirs throughout California allows us to store water during wet periods so that it can be used during dry periods. It is this water storage and delivery infrastructure that makes it possible for more water to be used in a year than falls from the sky. Water use in the Delta watershed, comprised of the Sacramento and San Joaquin River systems, includes in-Delta use, exports, and upstream depletions. The California infrastructure means that in wet years when dams are spilling, only about a quarter of total available water is used, but in dry years that can be as much as 80 percent of the available water.   

So, while water may be left instream to flow down the river, a substantial portion never gets to the Golden Gate. Instead, much of it is used to irrigate lands in the Central Valley.  

The Bay Delta Plan 

The State Water Project and the Central Valley Project have significantly impacted California’s water landscape, often favoring powerful financial interests. This has led to challenges, particularly for the Yuba River’s salmon population, as much-needed water is diverted before reaching its natural destination, the Golden Gate. 

The Update of the Bay Delta Plan offers a chance to address these issues.  The State Water Resources Control Board is currently considering updates to the plan.  This update focuses on the Sacramento River and its tributaries including the Yuba.   

The health of the salmon populations, other fisheries, and the Delta in general have continued to decline despite little change in total water use. According to recent studies, the decline in ecosystem health shows that the status quo for the amount of freshwater flowing under the Golden Gate Bridge is not enough to support these crucial resources. It is clear that more of our rivers’ water needs to reach the Bay-Delta, without upstream diversion or storage, to restore the health of the Bay Delta and supporting its beneficial uses. This would also restore the variability in river flow, which is crucial for sustaining native species like salmon.  

Now is the time to advocate for adequate water flows from the Yuba to the Golden Gate, ensuring the survival of our salmon and access to clean, affordable water for all Californians. 

For more information on the Draft Staff Report for the Update of the Bay Delta Plan, visit: Bay-Delta Watershed 2023 Report | California State Water Resources Control Board 

Public comment on the Draft Staff Report is due on January 19, 2024. 
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