The Yuba Watershed and the Bay-Delta Plan: Interlinked Plumbing and Management

Published 1/25/2024 | South Yuba River Citizens League

Salmon were once prolific in the Yuba watershed and the Sacramento River Basin. Historically, over 300,000 would return in the fall to spawn in the Yuba. But due to large dams blocking historical habitat, modification of river hydrology, and the lasting impacts of the Gold Rush, salmon and the Bay-Delta are on the brink of collapse. And there are no easy solutions. The water that is crucial to these ecosystems also grows the food we eat and powers our homes.

In response to the precipitous decline of native fisheries, the State of California is looking at solutions to restore some of the freshwater flows that the Delta and fish need. This process is commonly referred to as updating the Bay-Delta Plan. The current focus is on the Sacramento River and San Joaquin River, including the Yuba River. The Yuba to the Bay-Delta connection is critical for Yuba salmon because they depend on both ecosystems to survive.

Damming Habitat

A key driver in the decline of salmon are the dams that block their historical spawning and rearing habitat in the high reaches of a watershed. Salmon would begin their journey upstream in the spring or fall, depending on run type, and begin spawning in late summer to fall historically in the upper reaches of the watershed. The juveniles would then ride the flow of winter storms back downstream, eating as much as possible. On most California rivers, a rim dam prevents this natural migration. On the Yuba, the 260-foot Englebright Dam blocks upstream fish passage, preventing salmon from reaching the upper watersheds and tributaries on the South, Middle, and North Yuba Rivers. The habitat lost behind dams is staggering – over 80% of the historic habitat on the Yuba is blocked by dams.

Salmon are 6,000,000 years old, and over that time they have evolved to spawn in the cold, clear-water tributaries across the West (and East) Coasts. They relied on cool water less than 17^o C fed by the last of spring snowmelt and groundwater, and an abundance of gravel to spawn. The well oxygenated water from the pool-riffle complexes of high elevation tributaries kept eggs alive while buried in redds until the alevin emerged, And, as the juvenile salmon grew into fry, fall rains brought water up onto vegetated floodplains where the fry ate and began the journey downstream.

The introduction of dams dramatically altered the availability of this necessary habitat for salmon and has created unprecedented consequences for their survival.

Trading Water for Space

Many native fisheries in California are facing extinction. Spring- and Fall-run Chinook salmon have declined by 99% from their historic numbers, and Yuba steelhead by 99.4%. In 2022, only 3,164 Chinook salmon were counted in the Yuba. Despite efforts by the Anadromous Fish Restoration Program (AFRP) to reverse the negative trend in Chinook populations, their numbers continue to decline.

One of the main reasons for the continued decline is the lack of access to their historical habitat range. With as little as 10% of the historic habitat accessible in many places, there are bound to be challenges to recovery. Updates to the Bay-Delta Plan, therefore, must seek a more natural flow regime. The amount and timing of water must more closely mimic what occurred naturally prior to the construction of dams. And while no amount of water, habitat restoration, or more natural hydrologic signals can replace the loss of accessible habitat, if the “water-for-space” trade is going to be effective, salmon and the Bay-Delta need as much water as possible.

According to the State Water Resources Control Board’s (SWRCB) staff scientists’ 2017 Scientific Basis Report, which is being used to inform the update to the Bay-Delta plan, the water temperature was too high in the Yuba for the fish from May to September, even in wet years. As temperatures approach 20^o C, thermal stress on Salmon begins to affect their ability to hold and spawn. Temperatures above 25^o C can lead to half of Yuba salmon dying.

Plumbing the Yuba watershed

In the effort for a more natural flow regime, the primary challenge is the complex plumbing that has been constructed on the Yuba River. Englebright Dam, standing at 260 feet tall sits on the Yuba River downstream of where the North, Middle, and South Yuba Rivers come together. It is the upstream limit for fish migration into the Yuba Watershed. The dam blocks salmon from reaching their ancestral spawning grounds on the North, Middle, and South Yuba Rivers. But Englebright Dam is not the only infrastructure modifying flow in the Yuba. Upstream from Englebright Dam sits what is commonly thought of as one of the most complex and interlinked water storage systems in California. A series of canals, tunnels, diversion dams, forebays, and afterbays are managed by a complex network of federal agency rules. Local water agencies manage the facilities to meet the demands of power generation, water needs, and flood control. During the winter and spring months, water is stored behind dams to prevent flooding downstream and to store water for the future. In the spring and summer, when air conditioners are running and it’s growing season, that water is released to generate electricity, provide water to local irrigators, and pumped through a series of channels to Southern California. This alters the hydrograph to one that the salmon and the Bay-Delta ecosystem don’t recognize.

A conceptual figure of two hydrographs. Top, a natural hydrograph where discharge peaks with winter storms, tapering off into the summer. Bottom, a hydrograph modified by the presence of dams where the water from winter storms and snowmelt is stored and released for power generation and irrigation.

The Nevada Irrigation District (NID) owns and operates the Yuba Bear Hydroelectric Project. Most of the dams and infrastructure that comprise this project are concentrated in the upper reaches of the Middle Yuba, Jackson Creek, Canyon Creek, and the Bear River (outside the Yuba watershed). This system of dams and conduits, along with other water infrastructure owned by PG&E, helps deliver and direct water from the Middle Yuba River to Canyon Creek and the South Yuba. The most heavily impacted area by these inter-basin water transfers, though, is the Middle Yuba River. Water is moved from the Middle Yuba to Canyon Creek, and from there, into the South Yuba. Much of this water is then delivered out of the Yuba River watershed into the Bear River, although some of it is diverted back from the Bear River watershed into Deer Creek, part of the Yuba watershed. This process allows NID’s hydroelectric project to utilize water from the South Yuba for power generation and to meet water demands on the Bear River.

PG&E and the Placer County Water Agency (PCWA) also play significant roles in the Yuba watershed. Each entity owns and operates separate but overlapping infrastructure and conduits in the Yuba. PG&E owns the Drum-Spaulding Hydroelectric Project. This was PG&Es first major hydro project – it captures water from the tributaries of the South Yuba and diverts that water into storage reservoirs, sending the water through the Drum canal to the Bear River and eventually to western Placer County into the American River watershed.

Further downstream from NID’s Middle Yuba project, water from the Middle Yuba is also diverted into the North Yuba as part of the Yuba Water Agency’s (YWA) water projects. This water is stored in New Bullards Bar Reservoir for power generation at the New Colgate facility, located on the North Yuba.

Continuing downstream in the Yuba watershed, after the North and Middle Yuba Rivers come together, and the South Yuba joins them both near Bridgeport, the river flows into another YWA project. Englebright Dam, which is owned by the U.S. Army Corps of Engineers, and is managed by YWA through two power generation facilities. The older of the two is known as Narrows 1, and the more recent and larger capacity one is Narrows 2. Flows in the anadromous portion of the Yuba River between Englebright Dam and Daguerre Point Dam are controlled by YWA’s releases from Narrows 1 and 2, and, in the winter, spill over the top of Englebright Dam (which it was designed for). The final plumbing in the Yuba River before its confluence with the Feather River occurs near Daguerre Point Dam where three diversions occur: Cordua-Hallwood and Browns Valley Irrigation District to the north and Brophy Water District to the south.

With the movement of water within and between watersheds in the Yuba River watershed, it’s no wonder that ensuring a proportional and biologically meaningful amount of water makes it from the Yuba Watershed to the Golden Gate Bridge is a challenge. Updated studies won’t change the SWRCB staff scientists’ 2017 findings about the needs of the Bay-Delta and all the life that relies on it. How each watershed contributes to those targets needs to be tailored to each watershed. And equal weight must be applied to the SWRCB’s responsibility “To preserve, enhance, and restore the quality of California’s water resources… for the benefit of present and future generations.”

This map from 2010 shows the volumes of water moving within and outside the Yuba River watershed and who was responsible for the facilities at that time. The managing agencies and acre-feet of diversions have changed some over the last 14 years.

Guardians of California’s Water Resources and Yuba Salmon

The State Water Resources Control Board took charge of the Bay-Delta in 1978. The Board’s role in regulating the Bay-Delta and associated tributaries (including the Yuba watershed) is mandated by the federal Clean Water Act and the state Porter-Cologne Water Quality Act. The Board serves as the guardian of our state’s water resources. The Board’s mission is not just to preserve, but also to enhance and restore the quality of our water resources and drinking water. This mission recognizes their responsibility and their commitment to protect native fisheries and all beneficial uses of water. They strive to ensure that water resources are allocated properly and efficiently for the benefit of both present and future generations.

One of the Board’s key responsibilities is to allocate surface water rights, a charge that involves protecting both the public trust and public interest, while preventing the waste and unreasonable use of water. This is a complex balancing act, especially in the Bay-Delta, where many responsibilities and interests converge and conflict. An acre-foot of water delivered to the Imperial Valley to grow almonds for export is an acre-foot of water a farmer in the Delta doesn’t get for their produce for the local farmers market, or an acre-foot of water that isn’t supporting salmon health, which furthers the collapse of California’s commercial salmon fishing industry.

This balancing of beneficial uses is laid out in the Bay-Delta Plan. The last major update to the Plan was in 1995, with some small changes in 2006. In 2006, the Water Board affirmed its priority to protect salmon and beneficial uses related to salmon. The 2006 Bay-Delta Plan states, “Water Quality conditions shall be maintained, together with other measures in the watershed, sufficient to achieve a doubling of natural production of chinook salmon from the average production of 1967-1991, consistent with the provisions of State and federal law.” Nearly 18 years later, the native fisheries have declined and every water resource and beneficial use that the Board is responsible for is now severely degraded.

SYRCL’s hopes for the future:

In our formal comments on the Bay-Delta plan to the State Water Board, SYRCL stressed a number of points.

Freshwater Flow is Essential: Fish require a consistent flow of freshwater for survival that matches the timing they evolved with for over 6,000,000 years. (Re)constructing new habitat is an additional factor that contributes to their well-being.
Water needs to flow to the Golden Gate: Since the last update of the Bay-Delta Plan in 1995, the Delta has experienced a significant decline in the amount of water that makes it through the Delta and into the ocean, leading to severe ecological damage and the near collapse of the native fisheries. Water diversions and pumping have reduced the natural flow from the Delta to the Golden Gate by nearly half. Much of the water diversions occur during the biologically critical January-June period, affecting spawning, survival, and exacerbating the stress on native fish populations. Unfortunately, most of the current water that does make it to the ocean (known as “Delta outflow”) is unregulated and, therefore, unprotected from future use — water diverters could take the water for other uses if they have the water rights. This further threatens the region’s ecological balance and fishery resources, especially in the face of climate change.
Significant water is needed. The best available science shows significantly more water is the only option capable of providing the necessary flows to restore the native fishery. And that the timing of this water is also critical.
Watersheds are not equal. More analysis and tailored rules are needed for each watershed.
Shortcomings of the current Voluntary Agreements: The proposed Voluntary Agreements fall short of meeting the Plan Objectives. In their current form they contribute insufficient water to restore the health of the Delta and salmon.
Need for Collaboration: Collaboration among various stakeholders is essential to achieve the objectives and ensure the sustainability of the ecosystem.