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California’s delta: On the front lines of the state’s water issues

Stephanie Carlson researches native California fish populations in "intermittent streams" in the Sacramento-San Joaquin Delta. Photo: Edward Caldwell.
On June 3, 2004, a small trickle of water started to flow through a levee on the Jones Tract, a patch of farmland west of Stockton that sits below sea level. Of California's 27 million acres of irrigated croplands, the tract's 12,000 acres weren't exactly at the forefront of anyone's mind. But within a few hours the rivulet had become a deluge, opening a 350-foot-long gash in the wall that was built to hold back the waters of the Sacramento–San Joaquin Delta. The land quickly became a lake, submerging asparagus fields, corn silos, and dozens of homes beneath 60 million gallons of water. Repairing the break required six months of constant pumping and cost approximately $100 million; farmers throughout the Central Valley, who depend on the delta's 1,100-mile-long network of levees, had a new reason to lose sleep at night. The cause of the initial rupture was a beaver, working to expand its home.

California water: Few natural resources are as impressive, or as imperiled. Whether it's supplying 40 million domestic users, cooling the server farms of Silicon Valley, or irrigating the actual farms that supply half of the nation's produce, the importance of the state's aquifers and headwaters cannot be overstated. (Lake Tahoe, Yosemite Falls, and white-water rafting on the Kern and American Rivers feel like an embarrassment of riches.) While the potential for a multi-decade drought has grabbed headlines, however, California's water supply faces assault from a host of lesser-known factors including infrastructure failure, pollution, habitat loss, and plain old political chaos. This issue is strongly interdisciplinary, so it's only natural that UC Berkeley College of Natural Resources professors and students have been at the forefront of analyzing the problems and beginning the search for solutions. Several Berkeley professors have even served on the Delta Independent Science Board (DISB), a group of experts appointed by the state to oversee the quality of scientific research on California's contentious delta water issues.

Supply vs. demand

Professors and Delta Independent Science Board members Vincent Resh (right) and Richard Norgaard stand on a levee on Sherman Island along the Sacramento River. (Photo: Edward Caldwell)
When asked to name the three greatest threats to California's water, Richard Norgaard, Berkeley professor of energy and resources (and the DISB's first chair, who still serves on the board), couldn't be more clear.

“Issue number one, one, and one is that a substantial portion of the acreage in agriculture is supported through groundwater overdraft, even in normal-rainfall years,” he says.

According to the U.S. Geological Survey, California's cities, factories, and farms soak up about 38 billion gallons every day. And while most people think of water in terms of rivers, lakes, and rain, over a third of the state's supply comes from aquifers deep underground. Only one in six Californians relies on groundwater alone to supply their domestic needs.

“We've been mining water to expand use beyond surface-water allocations,” says Norgaard. “Groundwater is close to gone, and agriculture is saying, ‘Where's our water, where's our water, where's our water?'”

Given that much of California is a desert — and that decades-long droughts are not impossible — intelligently managing California's limited supply is crucial. Gov. Jerry Brown recently ordered municipalities to cut home water usage by a whopping 25 percent, and California residents gave themselves a well-deserved pat on the back when usage for July 2015 surpassed that target by 6 percent. But there's one problem: Domestic use accounts for only 10 percent of California's total water consumption. Agricultural use, on the other hand, accounts for closer to 40 percent.

At first glance, that doesn't seem entirely inappropriate. Fruits, vegetables, and nuts, not to mention Northern California's incomparable wine and cheese — why shouldn't the farmers who feed half of the nation take half of the water that the state has to offer?

“Do you know what percent of the state's economy is agriculture?” asks Vincent Resh, a professor in the Department of Environmental Science, Policy, and Management (ESPM) and another DISB member. “Less than 2 percent.” It's a very vocal 2 percent, though, and there are volumes of case law — and a good amount of political muscle — dedicated to maintaining the status quo. “I'm very sympathetic toward the plight of farmers in the delta,” Resh continues. And farmworkers are the poorest of California's poor, with seasonal unemployment rates reaching upwards of 60 percent. “It's the human side of the story that I've become extremely sensitive about.”

Nonetheless, Resh recalls being on a delta tour that was packed with people who identified themselves as delta farmers.

“They were all talking about how this has been their family heritage for generations, but they were working as lawyers and bankers," Resh said. "They were really talking about a way of life that was long gone for them personally, but a memory that they were holding on to. Actually, this ‘way of life' idea is true of many of the contentious water issues in California. The controversies over who gets the water in the Klamath River in Northern California and Oregon are as much about way of life as they are about water for agriculture and salmon.” 

A fragile water system

Nobody is suggesting an outright end to farming in California, but it's becoming increasingly clear that change is coming. One looming problem is the fragility of the levee system. Drive around Sacramento's rural environs and you'll realize that a lot of farmers actually do their work below sea level, with nothing but a hodgepodge system of peat dams and concrete rubble to restrain the brackish delta waters. Overactive beavers, like the one on the Jones Tract, are the least of the problem.

Like everyone else in California, the engineers who watch over the delta's levee system are at the mercy of probability, breathing a sigh of relief every day that goes by without the catastrophic shaking of the Big One.

“In any given year, there's not a large chance of a huge earthquake,” says David Sunding, UC Agriculture and Natural Resources Cooperative Extension specialist and chair of the UC Berkeley Department of Agricultural and Resource Economics. “But those risks accumulate over time. And by the time you look two decades into the future, there's a two-thirds chance of a very large quake that will affect the delta's water system.”

Even an apparent bounty — consecutive years of high rainfall — poses risks. River flows would rise along with reservoir levels, placing added stress on levees so that even a minor structural failure could set off a chain reaction, flooding fields and devastating crops.

“The current proposals for achieving reliable water supply and ecosystem health may be controversial, but it's clear that something has to be done — we can't have the status quo.”
— Vincent Resh

Inherent in either of these scenarios is the threat to drinking water. The delta houses the State Water Project, two massive pumps that send water to Southern California. If the levees are overtopped, the salt water of the bay will infiltrate the Sacramento and San Joaquin rivers, rendering the supply undrinkable.

“The worst-case scenario is three months without water,” Resh said. “And that's from Fremont down. Silicon Valley, Los Angeles, everything.”

Not just a human problem

Of course, farmers and thirsty urbanites aren't the only ones who need water. According to Berkeley Environmental Science, Policy, and Management associate professor Stephanie Carlson, “many of California's native fishes are declining, and the causes are rooted in habitat loss and the introduction of non-native fishes into California's waterways.” She emphasizes that our current multiyear drought may be the “nail in the coffin” for those populations already facing extinction.

Carlson's research focuses on understanding where and why fish populations are persisting. She found that several native fish, including commercially harvested salmon, live in “intermittent streams” — waterways that flow continuously in the wintertime but break into isolated pools during periods of low rainfall. As drought or human usage reduces stream flow, water quality deteriorates, resulting in higher temperatures and less oxygen. In pools that dry up completely, all fish die, of course, but some “refuge” pools persist through the summer — and these habitats do support fish.

Carlson's team has found that “the survival of imperiled salmon and trout varies among summers, but is highest after wet winters.” Following wet winters, streams flow longer into the summer, more pools persist, and water quality is improved. But, interestingly, “almost regardless of winter rainfall, most fish mortality is concentrated in late summer,” meaning that early, abundant fall rains may be as important as the previous winter's storms.

Carlson believes that these findings should guide management. Urban development in the Bay Area is spreading from flatlands to the hills.

“We need to focus our conservation efforts in those upper headwater streams — many of which are intermittent,” she says. Carlson also stresses that native fish have adapted to the seasonal shift from flowing streams to standing pools, while non-native fish have not — thus intermittent headwater streams may be important refuges for native fishes.

While diverting less water from streams during summer might help juvenile salmon, managing outcomes in the ocean is far more difficult. In 2007 and 2008, the West Coast Chinook salmon population collapsed, with the Sacramento River fall run reduced by 90 percent. Fisheries closed at a cost of millions of dollars, and the federal government declared a disaster. While the crisis was attributed to low ocean productivity beyond human control, human degradation of freshwater salmon habitats worsened the impact of poor ocean conditions.

Most salmon-breeding habitats in the Central Valley lie upstream of dams. Today, most Central Valley salmon are born in hatcheries; many circumnavigate the delta in trucks and are released into the San Francisco Bay. Because these fish don't swim through their natal rivers and the delta, they have no way to retrace their paths as adults. So they go everywhere, mingling with the broader gene pool. This “straying” erodes genetic differences among populations and increases the risk of collapse. It's possible that a more vibrant, genetically diverse salmon population could have better resisted the environmental disturbances of the mid-2000s.

“It's like having a broad portfolio of financial investments, as we've been taught with our 401(k)s,” Carlson says. “Maintaining multiple distinct populations with diverse traits and dynamics provides insurance against environmental change.”

—Excerpted from an article in the winter 2016 issue of Breakthroughs MagazineRead the complete article.

Posted on Friday, February 26, 2016 at 9:05 AM

Conservation organization California Trout helps establish endowed chair at UC Davis

Jeff Thompson, California Trout's executive director, does a little fly fishing on the McCloud River. He played a crucial role in establishing the organization's partnership with UC Davis to ensure that research, teaching, and outreach on wild trout, salmon, and steelhead will continue for many years.

California once teemed with millions of native salmon, trout and steelhead. The state has 31 distinct types of these iconic, majestic fish. But decades of degradation to aquatic habitat has depleted their numbers in many areas of the state. According to a report by UC Davis fisheries professor Peter Moyle and colleagues, 20 of these fish species are in danger of extinction within the next century. They are important species not just for the recreational or commercial benefits they afford, but also because they are a direct reflection of the health of the environment.

“Large self-sustaining populations of native salmon and trout are found where streams are in reasonably good condition,” Moyle wrote in his 2008 report, “SOS: California's Native Fish Crisis.” This report was commissioned by the conservation organization California Trout (CalTrout), which exists to support conservation science, education, and advocacy efforts to protect California's water resources and fisheries.

Moyle, whose academic home is the Department of Wildlife, Fish and Conservation Biology at UC Davis, is no stranger to CalTrout. He is the foremost authority on California's native freshwater and anadromous (sea-run) fishes and has been a leader in research and conservation efforts. His research has provided the core science essential to statewide conservation planning for freshwater and estuarine native fishes, especially salmon and trout. Graduate students who studied with Moyle now occupy many top-level fish ecologist and management positions in state and federal agencies, as well as key nonprofits like CalTrout.

A Russian River steelhead gets released back into the waters of this important North Coast waterway.
“Peter has been an invaluable resource and instrumental in establishing such a strong scientific foundation in our work,” said CalTrout's executive director Jeff Thompson.

In May of this year CalTrout and UC Davis announced the formal creation of the Peter B. Moyle and California Trout Endowed Chair in Cold Water Fishes. The endowment will provide crucial support for the chair holder's scholarly activities, teaching, and public service involving cold water fish and aquatic ecosystems. He or she will teach department courses, mentor graduate students, conduct research and outreach, and provide leadership in the conservation of cold water fishes and their ecosystems. The university recognizes that salmon, trout, and steelhead are the major drivers of many conservation efforts and will have the highest priority in the chair's program.

Most of the contributors to the endowment are CalTrout board members such as Nick Graves. He and his wife, Mary, explored many trails and trout waters in the Sierra Nevada over the years and have enjoyed larger rivers flowing from the Trinity Alps, Mt. Shasta, and the Siskiyou Mountains. “The opportunity to create a scientific chair whose research targets California waters, in perpetuity, is a comforting thought,” Graves said.

“I have worked with the organization since its earliest days and have always admired the dedication of its members to aquatic conservation,” Moyle said. “I am biased, of course, but I think CalTrout has made a very smart investment in the future by creating an endowed chair.”

Jacob Katz (left), director of California Trout's salmon and steelhead initiatives, and Professor Peter Moyle (right) are pictured at the Yolo Bypass, where their research is evaluating the importance of the area for rearing juvenile salmon.

 

Posted on Tuesday, September 30, 2014 at 8:58 AM

Flood protection, agriculture, fish and wildlife coexist in the Yolo Bypass

Egrets, herons and other birds feast in a wild rice field in the Yolo Bypass. (Photo by Trina Wood)
At times during the winter and early spring it looks like a vast inland sea between Sacramento and Davis. This is the Yolo Bypass, which shunts Sacramento River floodwater around the state capital during high flows. You drive over the bypass on a three-mile-long elevated stretch of Interstate 80 known as “the Causeway” (the Blecher-Freeman Memorial Causeway). The bypass is also the site of a lot of innovative fish and wildlife work.

From late fall through winter you can see thousands of ducks, geese and other waterfowl winging over the bypass’s flooded rice fields and the restored wetlands in the Vic Fazio Yolo Basin Wildlife Area. 

Black-crowned Night-Heron. (Photo by Trina Wood)
The Central Valley of California is one of the nation’s most important migratory waterfowl corridors. The bypass provides essential winter habitat for these birds on their annual migration. The wildlife area is managed by the California Department of Fish and Wildlife. Learn more.

A recent article in The Sacramento Bee featured a research project at a rice farming area in the upper reaches of the bypass that is examining how flooded fields could be used to fatten up young salmon during a crucial time in their life cycle. One part of the study is examining how soil type influences the production of insects — an important source of food for growing salmon. Carson Jeffres, a fish ecologist with the UC Davis Center for Watershed Sciences, is quoted in the story: "There are hundreds, if not thousands, of insects that are coming out of each 9-by-6-inch block of earth." You can also watch a YouTube video to hear UC Davis doctoral student Jacob Katz describe the project and read more about why fish find this floodplain so attractive in a previous Green Blog post by writer and photographer Trina Wood.

Part of the wildlife area is accessible by automobile — when it’s not flooded! Consider taking a tour of this remarkable and easily accessible area, or take binoculars to view the many birds. UC Davis fisheries professor Peter Moyle prepared a guide that will help you make the most of your visit.

Posted on Wednesday, February 27, 2013 at 7:13 AM

Wine and fish for dinner? Water management required

The competition between farmers and fish for precious water in California is intensifying in wine country, say biologists at the University of California, Berkeley.

Juvenile steelhead trout, shown here in a small stream pool, are hit hard when water levels are low. (Ted Grantham photo)
A recently published study links higher death rates for threatened juvenile steelhead trout with low water levels in the summer and the amount of vineyard acreage upstream. Like salmon, steelhead trout migrate from freshwater streams to the ocean before returning to their birthplace to spawn. Steelhead trout in Southern California and the upper Columbia River are endangered, and several other populations, including those in Northern California, are threatened.

The researchers found that juvenile steelhead trout are particularly at risk during the dry summer season typical of California’s Mediterranean climate. Of the juvenile steelhead trout present in June, on average only 30 percent survived to the late summer. In years with higher rainfall and in watersheds with less vineyard land use, the survival of juvenile trout over the summer was significantly higher.

The researchers pointed out that salmon and trout conservation efforts have not adequately addressed summer stream flow. Previous studies have highlighted other limiting factors such as habitat degradation and water quality, while this study documented the importance of water quantity for restoring threatened populations.

Aerial view of vineyard agriculture in Sonoma County. Vineyards that divert water from streams used by juvenile salmon and steelhead trout could reduce their impacts by storing winter rainfall in small ponds such as the ones seen in this photo. (Adina Merenlender photo)
“Nearly all of California’s salmon and trout populations are on the path to extinction and if we’re going to bring these fish back to healthy levels, we have to change the way we manage our water,” said lead author Theodore Grantham, a recent Ph.D. graduate from UC Berkeley’s Department of Environmental Science, Policy and Management (ESPM). “Water withdrawals for agricultural uses can reduce or eliminate the limited amount of habitat available to sustain these cold-water fish through the summer.

Grantham says he is not suggesting we get rid of vineyards. “But we do need to focus our attention on water management strategies that reduce summer water use. I believe we can protect flows for fish and still have our glass of wine.”

Posted on Friday, May 18, 2012 at 10:20 AM
  • Author: Ann Brody Guy
  • Adapted from an article by: Sarah Yang

Bleak future for spring-run Chinook salmon

Spring-run Chinook salmon, photographed in Butte Creek (Allen Harthorn/Friends of Butte Creek)
Warming streams could spell the end of spring-run Chinook salmon in California by the end of the century, according to a study by scientists at UC Davis, the Stockholm Environment Institute (SEI) and the National Center for Atmospheric Research (NCAR).

There are options for managing water resources to protect the salmon runs, although they would impact hydroelectric power generation, said UC Cooperative Extension associate specialist Lisa Thompson, director of the Center for Aquatic Biology and Aquaculture at UC Davis. A paper describing the study was published online recently in the Journal of Water Resources Planning and Management.

“There are things that we can do so that we have the water we need and also have something left for the fish,” Thompson said.

Working with Marisa Escobar and David Purkey at SEI's Davis office, Thompson and colleagues at UC Davis used a model of the Butte Creek watershed, taking into account the dams and hydropower installations along the river, combined with a model of the salmon population, to test the effect of different water management strategies on the fish. They fed in scenarios for climate change out to 2099 from models developed by David Yates at NCAR in Boulder, Colo.

In almost all scenarios, the fish died out because streams became too warm for adults to survive the summer to spawn in the fall.

The only option that preserved salmon populations, at least for a few decades, was to reduce diversions for hydropower generation at the warmest time of the year.

“If we leave the water in the stream at key times of the year, the stream stays cooler and fish can make it through to the fall,” Thompson said.

Summer, of course, is also peak season for energy demand in California. But Thompson noted that it might be possible to generate more power upstream while holding water for salmon at other locations.

Hydropower is often part of renewable energy portfolios designed to reduce greenhouse gas emissions, Purkey said, but it can complicate efforts to adapt water management regimes to a warming world. Yet it need not be all-or-nothing, he said.

“The goal should be to identify regulatory regimes which meet ecosystem objectives with minimal impact on hydropower production,” he said. “The kind of work we did in Butte Creek is essential to seeking these outcomes.”

There are also other options that are yet to be fully tested, Thompson said, such as storing cold water upstream and dumping it into the river during a heat wave. That would both help fish and create a surge of hydropower.

Salmon are already under stress from multiple causes, including pollution, and introduced predators and competitors, Thompson said. Even if those problems were solved, temperature alone would finish off the salmon — but that problem can be fixed, she said.

“I swim with these fish, they're magnificent,” Thompson said. “We don't want to give up on them.”

Other co-authors of the paper are graduate student Christopher Mosser and Professor Peter Moyle, both in the Department of Wildlife, Fish and Conservation Biology at UC Davis. The study was funded by the U.S. Environmental Protection Agency.

Posted on Friday, September 16, 2011 at 11:17 AM
 
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