Dutch Slough Laboratory

Dutch Slough Laboratory

For a hawk’s-eye view of one of the Estuary’s most ambitious restoration efforts, visit the Dutch Slough Tidal Marsh Habitat Restoration Project’s YouTube channel. Drone-shot footage shows what the Department of Water Resources has been doing on 1,200 acres of former wetland, converted to pasture and subsided up to 15 feet, in the West Delta between Big Break and Jersey Island. After moving millions of cubic yards of soil to elevate the marsh plain, a team of engineers, scientists, and...
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Scientists Nail Climate Links to Extreme Events

While a supermajority of Americans finally believe we are warming the world, a 2020 Yale Climate Opinion survey shows that most people still aren’t very worried about it. “Climate change is abstract to them,” says UCLA climate scientist Daniel Swain. “They don’t connect it to their personal lives.” But Californians do. Reeling from a decade of record-shattering drought, heat waves, and wildfires, people in the Golden State overwhelmingly tell Public Policy Institute of California pollsters that the effects of global...
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Sub-Standard Snow

At a glance, the recent winter storms and inches of snow in the Sierra seem like a reassuring sign: more snow means more snow melt, which means more water moving through our freshwater systems during dry summer months. But it turns out that there are different types of snow with differing levels of moisture locked up inside — and the latest Sierra snowfall appears to be holding less water than usual. This means the Bay’s streams and estuaries could have...
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Sediment Paparazzi

As the Estuary faces drowning marshes due to rising seas, people want to see action – acres saved, walls built, marsh mice whisked to safety after crawling to the tip of the tallest gumplant. In terms of action, “sediment monitoring” doesn’t come immediately to mind. Monitoring is something you do after all the action is over, isn’t it? And as for “sediment,” well what’s all the fuss over some dirt and mud? In fact, there is quite a fuss. The...
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North America’s largest and most ancient freshwater fish species, white sturgeon, hang out in some kinds of Estuary waterways more than others, scientists find.

 Researchers with the U.S. Geological Survey found that adult and sub-adult white sturgeon occupy deep open-water channels and shallow open-water shoals in equal measure, but don’t use shallow wetland channels. As a group, white sturgeon are characterized as amphidromous, meaning they regularly migrate between freshwater and the sea, in both directions, but not for the purpose of breeding. According to the study, which appears in the December 2020 issue of San Francisco Estuary and Watershed Science, adults in the local...
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Filling significant recently identified gaps in monitoring spring-run Chinook is critical to protecting these threatened Central Valley salmon.

“There’s no way we can manage them for recovery if we don’t understand the biological processes that govern their dynamics through time and space,” says UC Santa Cruz/NOAA salmon expert Flora Cordoleani, lead author of a study reported in the December 2020 issue of San Francisco Estuary and Watershed Science. Cordoleani and colleagues identified the monitoring gaps while building a model of the spring-run Chinook life cycle. The model accounts for three self-sustaining populations of these at-risk fish, assessing survival...
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Science in Short ~ Podcast

David Ayers: How Fish Interact with Wetlands Topography  In this podcast, Estuary News reporter Alastair Bland and UC Davis PhD student and fish researcher David Ayers discuss the Sacramento-San Joaquin Delta, its fish, its marshlands, its flows, and its future. Ayers explains the focus of his research, which seeks to reveal how underwater topography in the wetlands fringing the estuary affects interactions between predators and small fish. While restoration projects often focus on adding more water to this ecosystem and...
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A Fragile Fleet

The naming of boats and ships is a serious matter. Each larger vessel’s name starts with a code that tells what it carries, what propels it, or what purpose it serves. If it were your hobby to keep tabs on traffic on San Francisco Bay, you’d see a lot of big UCCs (container ships) and TCHs and TCRs (tankers). You’d see ferries emblazoned with MV, standing for “motor vessel.” Before COVID-19, you would have spotted the occasional SS, standing for...
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A team of scientists is close to chasing down every last thing that happens to nitrogen in wastewater as it passes through the soils and plants of a horizontal levee.

Not only is 97% of the nitrogen removed, but also trace pharmaceuticals. “You just have to focus on where the water is going,” says environmental engineer Aidan Cecchetti, referring to the UC Berkeley-Stanford-ReNUWIt team’s experimentation with three components of flow through the levee system—under the surface, over the surface, or into the air (through evapotranspiration). “In the wastewater pumped to the subsurface, you see full removal of every contaminant except phosphorous.” What’s most astonishing is how much of the work...
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Surface water diversions in California’s Central Valley can be estimated based on readily available climate data, say researchers—a boon to efforts to track groundwater use.

Valley groundwater pumping is calculated as the total water demand minus surface water deliveries. However, today’s water model relies on individually reported diversions across the entire valley, and compiling all these data is a slow process; by the time the numbers are crunched, assessments of groundwater use are already outdated. “It can take years,” says Jordan Goodrich of University of Waikato in New Zealand. “It’s one of the biggest problems we face in tracking the Central Valley water budget.” Overdrafting...
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New Eyes on Floods and Fire

By Jacoba Charles Flames have become the unofficial face of climate change for Sonoma County, in the wake of the catastrophic Tubbs and Kincade fires that tore through the northern parts of the county in 2017 and 2019. Together the two fires burned more than 114,000 acres, roughly a tenth of the county, claimed 22 lives, and destroyed almost 5,000 homes. However, increased frequency and severity of wildfire is only one of the many ways that climate change is poised...
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Toxins Flock to Beads in a Scientific Tea Bag

By Ashleigh Papp When a New Zealand scientist shared a novel method to test water quality in the early 2000s that didn’t involve harvesting shellfish, UC Santa Cruz’ Raphael Kudela and his team of researchers quickly adopted the idea. After some fine-tuning, they named their new technique Solid Phase Adsorption Toxin Testing (SPATT, for short). The technique takes advantage of custom-built plastic, or resin, beads that are designed to absorb specific things. “It looks a lot like a tea bag,”...
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Tracking Curlews Cross-Country

By Joe Eaton This winter, Jay Carlisle, director of the Intermountain Bird Observatory, teaming with Nils Warnock of Audubon Canyon Ranch and netting expert David Newstead of Coastal Bend Bays and Estuaries Program, caught two long-billed curlews and outfitted them with transmitters. Those birds may reveal where the wintering curlews on the California coast and Bayshore are coming from. While many grassland birds are experiencing catastrophic declines, long-billed curlews had appeared to be an exception. “It’s such a habitat generalist...
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Jan Thompson has always been most interested in what happens down at the bottom of the Bay.

The zone of interaction between the critters in the oozes and the water column above—where specks of sediment, nutrients, and fish food cycle through clam siphons into the Estuary—is the particular specialty of this US Geological Survey scientist. “I’m most proud of the research I’ve done establishing a solid connection between bivalve grazing and phytoplankton growth,” she says. When USGS first hired Thompson, who retired in October 2019, most women in the Menlo Park office were secretaries. She’s since trained...
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Rainer Hoenicke is optimistic about the changes he saw in his five years as the Delta Stewardship Council’s Science Director.

“People are coming to the table and realizing we need to be anticipating and forecasting how to adapt,” he says. Prior to joining the Science Program, Hoenicke served for nearly a decade as deputy and executive director of the San Francisco Estuary Institute, where he managed two Boards of Directors and reorganized the Institute’s program areas. “I felt challenged to do something different,” he says of the move, “since the Delta is much more controversial territory.” In Hoenicke’s eyes, the...
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A new system for treating agricultural drainage water in the Delta could also help rebuild subsided islands.

The approach—known as a Chemically Enhanced Treatment Wetland—combines chemical treatment with natural wetland processes; researchers tested it on Twitchell Island, which features corn and rice crops, as well as wetlands. They dosed agricultural ditch water with dissolved organic material (DOM), then treated it with a coagulant to precipitate the DOM, forming flocculant. The resulting water then passed though treatment wetlands, where the flocculant settled and blended with plant detritus in the sediment. The study, reported in the September 2019 San...
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Manmade features in the Delta, including riprap-armored banks, water diversion pipes, pilings, and woody debris, may be sending juvenile native fishes into the jaws of finned invaders.

“We know from a decade of doing survival studies that migrating juvenile salmon are dropping out of the system pretty much everywhere in the Delta,” says UC Santa Cruz fisheries biologist Brendan Lehman. “Physical habitat features are potentially aggregating predators and prey in ways detrimental to salmon smolts and steelhead.” The scientists report in the December 2019 San Francisco Estuary and Watershed Science that artificial light and submerged aquatic vegetation pose the most severe and widespread risks to native fishes....
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Levels of pyrethroid insecticides spike sharply in the North Delta’s Cache Slough during winter rainstorms, rendering the water so toxic that it decimates laboratory populations of a half-inch crustacean called Hyalella azteca.

However, according to a study reported in the September 2019 San Francisco Estuary and Watershed Science, Hyalella collected in the wild from Cache Slough are resistant to pyrethroids. Genetic analysis revealed that, collectively, Hyalella in the slough have four mutations for pyrethroid resistance. They also have a fifth mutation for resistance to organophosphates and likely carbamates, two additional major classes of pesticides that are applied extensively on agricultural and urban lands. “Hyalella are special,” explains co-author Helen Poynton, a molecular...
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Researchers hope new computer models will help clarify the effects of entrainment on the population of endangered Delta smelt.

Entrainment at the South Delta pumps of the State Water Project and the Central Valley Project has been a concern for years, but disentangling its impact on the dwindling smelt population from those of other environmental and water management factors isn’t easy, and operational differences between the SWP and CVP facilities complicate analysis. Now, US Fish and Wildlife Service statistician Will Smith has developed computer models for entrainment effects on different smelt life stages, part of a larger Delta Smelt...
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While the acreage of wetland restoration projects is growing throughout the Delta, scientists are still working to understand how best to help these areas become fully functioning, complex habitat as quickly and successfully as possible.

A study published in September’s San Francisco Estuary and Watershed Science shed light on some essential questions about what triggers seed generation in wetland habitat. “Wetland restoration practices can be enhanced by a solid understanding of basic plant life history and species ecology,” says co-author Taylor Sloey of Yale-NUS College in Singapore. The researchers looked at three questions: what seeds are present in the seed bank (the viable seeds that accumulate naturally in the soil), and how exposure to cold...
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