Of California’s many tough water challenges, few are more intractable than regulating how much water must be kept in rivers and streams to protect the environment.

Attempts to require enough water at the right time and temperature to sustain fish and other aquatic life run smack against a water rights system developed more than 150 years ago for farmers, miners, industries and cities – but not wildlife.

Federal and state endangered species laws have been instrumental in establishing such “environmental flows” on some California streams, but those requirements are usually tailored for an endangered or threatened fish – a single-species approach that critics say has little progress to show for the resulting disruption of irrigation and urban water supplies serving nearly 40 million residents.

But now, a new strategy developed by scientists to end the stalemate is gaining momentum. Gov. Gavin Newsom has already made the blueprint a key element of his plans to recover salmon populations and build climate resilience in California’s water systems.  

Known as the California Environmental Flows Framework, the scientists’ strategy shifts the focus of environmental water management from single species to entire ecosystems. It departs from the state’s longstanding rules that set fixed amounts of water to be left in streams for fish.

On dammed rivers, environmental flows are managed by releasing water from reservoirs. The blueprint calls for varying timing and amount of reservoir releases year-round to mimic patterns of natural river flows that support ecosystem health — for example, flows that promote salmon migration or improve spawning habitat for native species like the rare foothill yellow-legged frog.

“We’re trying to take a step back and think more holistically,” said Sarah Yarnell, a University of California, Davis research hydrologist who helped develop the guidance document with a consortium of scientists at universities, state agencies and nonprofit groups.

Architects of the framework say it will help produce scientifically defensible and efficient approaches to determining what is arguably the most contentious point in setting stream protections: How much water is needed to protect fish and entire river ecosystems and when?

The blueprint is already being used for rivers that wind through California’s famed vineyards and ancient redwood groves, and streams that feed a Northern California lake of cultural importance to Native American tribes.

“There’s movement and progress definitely happening in California,” Yarnell said.

Overcommitted Rivers

Like many other Western states, California is ill-equipped to carve out slices of water specifically for fish because most of its rivers are already overcommitted.

As the state rapidly developed during the Gold Rush, people claimed large stakes to rivers and the trend continued through the 20^th century. The state issued rights to divert water from rivers under the doctrine of prior appropriation – a first-in-time, first-in-right system – with little regard for the environment.

“Few streams in California have legally recognized environmental flow protections.”
~Scientists with the California Environmental Flows Framework group

Over time, water demands outpaced the supply of many streams. In a 2015 study of the state’s water rights database, University of California researchers Ted Grantham and Joshua Viers found the state has greatly over-allocated the flows of its largest rivers.

Natural resource agencies and environmental groups have been pursuing rules to keep streams habitable for fish since at least the late 1970s. These rules, known as instream flow protections, require minimum amounts of water at specific locations and times of year. 

Over the decades, recommendations for flow limits have been submitted to the State Water Resources Control Board, which regulates water quality and water rights. To date, however, the board has been sparing in their adoption, according to Yarnell and fellow scientists on the blueprint team.

“Few streams in California have legally recognized environmental flow protections, where regulators have set the amount and timing of water to be left instream to support fish, wildlife, and habitat maintenance and creation,” the scientists said in a California WaterBlog post.

Read More: Delta at Epicenter of Debate over ‘Environmental Flows’ for Rivers 

A patchwork of requirements provides some level of protection for fish. Federally regulated hydropower producers must ensure specific flow levels at key times for fish listed as federally threatened or endangered with extinction. Lawmakers have preserved flows for fish by designating sections of streams as “Wild and Scenic.” Although rarely enforced, a state fish and wildlife code over a century old requires all dam operators in California to release enough flow “at all times” to keep fish “in good condition.”

These rules may prevent streams from going dry but don’t always create the right conditions for breeding, migration and other needs of aquatic species.  

Collectively, the scattershot of protections across the state hasn’t had the intended results. UC Davis researchers estimate more than 80 percent of California’s native fish remain vulnerable to extinction, and fisheries managers recently canceled salmon fishing on California’s rivers and offshore for the second consecutive year due to low populations.  

“We have seen decades of failure to protect critical ecological needs,” said Brian Gray, a senior fellow at the Public Policy Institute of California who has written extensively on developing environmental flow standards.

Other Western states have taken a different approach to protecting flows for fish.

Colorado, whose water rights laws are also based on prior appropriation, gives its state Water Conservation Board the unique power to hold water rights solely for preserving the natural environment. For over-allocated streams, the board attempts to buy or lease water rights from owners. Oregon has a similar program that allows water rights holders to lease their shares to the state for the benefit of fish for up to five years.

A More Scientific Approach

Developing a scientifically defensible flows proposal has traditionally been a painstakingly long and complicated process.

A technically sound plan can take years to craft and requires the help of hydrologists, geologists, biologists, water quality analysts and other experts. The process must also account for the wide range of human uses and regulatory requirements on rivers and streams. Whether developed by the California Department of Fish and Wildlife or a non-governmental group, the proposal must be approved by the State Water Board or in some cases a judge.   

Frustrated by the arduous process, a group of scientists huddled and compared notes. They eventually developed the blueprint for a more streamlined and more scientific, multi-species approach to establishing minimum flows in any watershed.

“California is huge and diverse, and everyone was developing flows differently,” UC Davis’ Yarnell said. “This method saves time … people don’t need to study the heck out of the stream.”

The blueprint pinpoints when a stream’s five distinct natural flow periods typically occur. For example, the fall pulse flow that happens after the first major storm or the spring “recession” flow during the transition from the wet to dry season.

Knowing the timing and magnitude of these conditions allows users to create a schedule that ensures ample stream flow to transport sediment, send migration and spawning cues to fish and keep streams cool and fresh during dry spells.

“The framework helps work through the science of a particular river segment, the geomorphology, the natural unimpaired flow patterns, the ecology and also how the system has been altered,” Yarnell said.

The system not only gives users a scientific foundation but also helps them identify other water uses such as irrigation or hydropower and the relevant laws that should be considered in a flow plan. Intended users include scientists, state agencies, non-governmental organizations and local streamkeeper or watershed groups.

“Our hope is that for systems where there isn’t a huge amount of resources or investment, the framework can help provide information to move the process forward at a lower cost,” said Bronwen Stanford, lead river scientist in The Nature Conservancy’s California Water Program.

Stanford is on the framework’s 15-person technical team that includes scientists with the State Water Board and Fish and Wildlife Department, UC Davis, UC Agriculture and Natural Resources and California Trout. The team continues to test and refine the blueprint, which was funded by the state and the conservancy.

Framework Mobilized

When California trudged through a bitter drought in the summer of 2020, Gov. Newsom unveiled a sweeping list of water strategies and called on state agencies to develop “rapid methodologies” that can be used to set instream flow recommendations. 

“We’re lucky in California to have a lot of recent advances in these hydrology methods.”
~Robert Holmes, state freshwater biologist

“State and federal laws enacted to protect against reduced river flows and loss of habitat have been unevenly applied and only partially successful,” Newsom’s 140-page Water Resilience Portfolio states. “Help regions better protect fish and wildlife by quantifying the timing, quality and volume of flows they need.”

In the three years since, the state wildlife department has used the new blueprint in developing stream flow criteria for several salmon and trout-bearing watersheds, including the South Fork Eel River, West Fork San Gabriel River, the Ventura River and Mark West Creek, a major Russian River tributary.

“We’re lucky in California to have a lot of recent advances in these hydrology methods,” said Robert Holmes, a freshwater biologist who manages the department’s environmental program. “The California Environmental Flow Framework has been a really valuable tool.”

Holmes, who oversees the department’s stream flow studies, said researchers are using the framework with tribes to calculate flows needed to protect the threatened Clear Lake hitch in tributaries feeding Northern California’s Clear Lake, as Newsom directed in an executive order last year.

The framework is also being used to preserve water for threatened coho salmon and steelhead trout in Mendocino County’s Navarro River watershed, famous for its coast redwoods and cool-climate wines. The river often has too little water during the summer for both juvenile fish and vineyards, but plenty during winter and spring.

The Nature Conservancy and its partners used the blueprint to build on previous flow studies in the watershed and came up with a solution: Capture more flows during the rainy season and limit pumping from the river in the summer. Some local grape growers and other water users took to the idea, building ponds to store river flows and installing more efficient pumps.

The collaborative effort helped keep the Navarro flowing year-round, the Nature Conservancy’s Stanford said, and is a prime example of how the scientists’ framework can be used to accommodate people and wildlife.

The holistic approach will likely remain a key strategy as the state tries to protect its most ecologically important watersheds.

Newsom gave the scientists’ blueprint explicit support in January when he introduced a new statewide salmon plan. State fish and wildlife officials are using the framework to set flow schedules on several critical salmon streams for the State Water Board’s consideration by next year. It also calls on state agencies to jumpstart groundwater recharge projects, water storage ponds and other activities to keep more water in the Navarro River and other North Coast streams.

“Salmon are an integral part of our shared history in California,” Newsom said in announcing the plan. “We’re doubling down to make sure this species not only adapts in the face of extreme weather but remains a fixture of California’s natural beauty and ecosystems for generations to come.”

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Editor’s Note: Nick Cahill no longer works at the Water Education Foundation. For inquiries about this story, email Vik Jolly, News & Publications Director, at vjolly@watereducation.org

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