Science in Short: Daylighting Delta Data

Delta Landscapes & Waterways



13
Apr

Science in Short: Daylighting Delta Data

Once you know how many fish are present in a particular part of a river, including additional details like the time of day and water temperature, what do you do with this information? For decades, Delta researchers have collected millions of similar data points from daily visits to the San Francisco Estuary, not all of which are available or immediately useful. How that information is then translated into a language relevant to water and conservation managers requires serious number, or data, crunching. Sam Bashevkin, senior environmental scientist at the Delta Science Program in the Delta Stewardship Council, is working to bring data science to the San Francisco Estuary and help to make sense of the overwhelming data troves generated by...
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Will Salmon Simmer Again?

After two critically dry years that coincided with Trump-era rollbacks to environmental protections, some iconic Delta fish are closer than ever to the point of no return. Last fall, the fall midwater trawl found zero wild Delta smelt, while a coalition of environmentalists and fishermen is asking a federal court to help prevent a repeat of 2021’s near-obliteration of endangered winter-run Chinook salmon. Their lawsuit is just one of several projects....
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15
Feb

Let’s Not Forget Suisun Marsh

I started sampling the fishes of Suisun Marsh in 1979 because one of my UC Davis graduate students was looking for a place to study tule perch, a live-bearing native fish. We found not only a lot of tule perch in the marsh, but also an abundance of other native fishes. Clearly, this was a good place to study species for which we had little information at that time. Two things helped with our new project. First, sampling boats could be launched less than an hour’s drive from campus. Second, the California Department of Water Resources needed a study to examine effects of new tidal gates on fish. The gates are designed to retain fresher water in the marsh to...
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15
Feb

Sturdy Sturgeon

A 90-year-old Australian lungfish at San Francisco’s Academy of Sciences has received a lot of press lately, but there is a wild fish species living in the San Francisco Bay that has the potential to live that long or longer — or so we think. While one white sturgeon caught in the Columbia River Basin was estimated to be 104 years old, the life expectancy of white sturgeon, Acipenser transmontanus, which includes the Central Valley population endemic to the San Francisco Bay, is hard to pin down. “There are old ones out there, but it’s really hard to give a number because we just don’t have it,” says John Kelly, statewide sturgeon coordinator for the California Department of Fish and...
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15
Dec

Scientists in the Central Valley are honing a novel way of giving young salmon the nourishing benefits of wintertime floodwaters without undertaking costly floodplain restoration work.

The method, being practiced along the Sacramento River, mimics the flood patterns of natural Sacramento Valley wetlands by diverting water onto floodplain farm fields, retaining it there for three weeks, and finally flushing the water—now rich with zooplankton and invertebrate protein—back into the river. Onsite studies have shown that salmon smolts grow faster when provided with this supplemental nutrition source, giving the method promise as a tool for boosting survival rates of outmigrating juveniles and, ultimately, helping sustain imperiled Chinook runs.     Jacob Katz, a California Trout biologist helping lead the project, explains that flushing river water over dry land and then back into the river effectively “reenergizes the food web,” allowing terrestrial carbon to flow into the water where...
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15
Dec

Hot off the press, Sacramento County Breeding Birds: A Tale of Two Atlases and Three Decades of Change raises red flags for some of the county’s wetland species.

Breeding bird atlases use field observations to record possible, probable, or confirmed nesting in uniform-sized blocks within a county or state. Biologist/artist Tim Manolis led a Sacramento County atlas project in 1988-93, but the results were never published. When Edward Pandolfino of Western Field Ornithologists heard about it he suggested repeating the effort and packaging the two data sets together. The second Sacramento atlas, covering 2016-20, followed the lead of recent state atlases in the eastern US in using data uploaded to the birding app eBird to supplement targeted observations. “It’s a lot more efficient, and lets everybody get involved,” says Pandolfino, lead author of the publication.   Overall avian species richness didn’t change significantly, but distributions did for many...
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15
Dec

A large pulse of water sent through the Yolo Bypass in summer 2016 boosted phytoplankton biomass and food web conditions in Cache Slough and the lower Sacramento River, a new report confirms.

 “Our goal was to improve estuarine habitat by increasing net flows through the Cache Slough Complex to enhance downstream transport of lower trophic-level resources, an important driver for fish such as the endangered Delta Smelt,” write the authors—including esteemed (and recently retired) California Department of Water Resources lead scientist Ted Sommer—in the latest issue of San Francisco Estuary and Watershed Science. The pulse occurred over three weeks in July, a time when flows in the region above Cache Slough are often negative (meaning they go “upstream”) due to agricultural diversions and low freshwater inflow. Producing the pulse, which increased downstream flows from about negative-two cubic meters per second to a peak of 15 cubic meters per second in the Toe Drain...
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25
Oct

Breaching Season for Hill & Dutch Sloughs, Pacheco Marsh

In the life of a tidal wetland restoration project, the first levee breach is a major milestone, a kind of graduation. After years of securing funding, navigating the permit process, completing baseline biological surveys, filing endless reports, grading and sculpting the marsh plain, setting out plants—after all that comes the day when the earthen barrier crumbles, the water makes its move, and another marsh can start to regenerate. This fall, that’s happening around the Bay Area as three significant projects—Dutch Slough and Lower Walnut Creek in Contra Costa County and Hill Slough in Solano County—renew long-severed connections between water and land. The three projects involve two state agencies, a county district, and a nonprofit. Dutch Slough is a California Department...
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20
Aug

Loss of wetland habitat in the Delta has reduced net primary productivity by 94%, but achieving current restoration goals could restore 12% of this loss.

In a new study published in the September 2021 issue of Science of The Total Environment, researchers modeled net primary production of the Delta under historical and contemporary conditions in order to project the potential benefits of restoration. The loss of net primary productivity—the amount of energy available to pass up the food chain—associated with human modification of the Delta since the early 19th century has reduced the energy available to support biodiversity and ecosystem services. Using the San Francisco Estuary Institute’s Historical Ecology Project, which modeled the early Delta based on archival photos, maps, and texts from the early 1800s, researchers estimated the total area for five specific habitat types: open water, tidal marsh, non-tidal marsh, riparian forest/scrub, and seasonal floodplains. The...
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20
Aug

When it comes to managing Delta salinity, a new research paper suggests we treat public policy like a science experiment.

As anthropogenic factors like salt accumulation through irrigation and freshwater storage combine with drought and sea-level rise, the Delta is headed for a saltier future. The June 2021 paper, published in San Francisco Estuary and Watershed Science, integrates biological and physical sciences to draw a comprehensive picture of Delta salinity and changing freshwater inflow. Changing salinity patterns could have a profound impact on the region’s ecology, affecting how and when fish like the Delta smelt or Coho salmon spawn, and which aquatic plants survive. The paper insists that the patterns observed suggest that the future will be difficult to predict, as extreme weather events will lead to bigger fluctuations in salt levels, and recommends that management agencies encourage interdisciplinary coordination when approaching future...
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23
Mar

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 contractors led by project managers Katherine Bandy of DWR and Mark Lindley of Environmental Science Associates has carved channels and created a basin-and-range landscape on the Emerson and Gilbert parcels, the western two-thirds of the project site. “We spent a...
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01
Mar

As agencies wrangle over how best to protect the Delta’s dwindling native fish species, researchers want to see more consideration to the needs of the estuary’s birds.

 “If we want to restore the ecology of the Delta, we can’t just be looking in the water,” says Kristen E. Dybala of Point Blue Conservation Science. In a paper published in San Francisco Estuary and Watershed Science, Dybala and two co-authors make the case that “birds and their habitat needs are often not addressed in science syntheses, conservation planning, and large-scale restoration initiatives in the Delta.” While some birds use the same sloughs and channels that support such high-profile fishes as Chinook salmon and Delta smelt, other bird species rely on habitat types that fringe the Delta’s waterways. Indeed, while general habitat restoration in the Delta can provide multiple benefits for humans, fish and many birds, the authors observe...
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01
Mar

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 of key life stages (eggs, fry, smolts and adults) as well as in key habitats (natal creeks, the Sacramento River, floodplains in the Sutter and Yolo bypasses, the Sacramento-San Joaquin Delta, and San Francisco Bay). “It’s a complex model, and...
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18
Nov

Current estimates of young salmon lost to the south Delta pumps are based on a smattering of studies from the 1970s and should be updated, according to a new analysis.

“They don’t represent current operations,” says Ukiah-based consultant Andrew Jahn, lead author of the analysis reported in the September 2020 issue of San Francisco Estuary and Watershed Science. Current operations at the State Water Project (SWP) and the Central Valley Project (CVP) can reverse flows in the Old and Middle rivers, diverting salmon on their way to the ocean towards the projects. Existing salmon loss estimates also fail to account for a likely Old River hotspot for predators, drawn to the influx of salmon and other fish near the two water projects. Evidence of this hotspot lies in the numerous acoustic tags from young salmon to be found in the sediment, which were presumably defecated by striped bass, as well as...
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Science-in-Short ~ Aquatic Weeds Podcast

Wall-to-Wall Sampling of the Delta’s Aquatic Weeds Via Remote Sensing, an interview with Shruti Khanna.  In this episode of the podcast, Estuary News reporter Daniel McGlynn talks to Dr. Shruti Khanna, a senior environmental scientist at the California Department of Fish and Wildlife. Their conversation focuses on Khanna’s use of remote sensing technology to study the Sacramento-San Joaquin Delta. Specifically, Khanna analyzes and processes remote sensing data, or high- resolution images collected by sensors mounted on aircraft, to study invasive plant species growing in Delta waterways. Researchers also use remote sensing to study the Delta’s water quality, fish populations, and overall change. While remote sensing will never replace on-the-ground research, the massive data set produced by collecting large-scale images over...
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28
Sep

Science in Short ~ Fish 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 encouraging that water to overflow the river’s banks, Ayers says small fish need more than just water and wetlands to survive. Variation in habitat features, such as the width and depth of wetland channels that wind through these ecosystems, create a...
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22
Sep

Londons Roam and Feast on the Bay circa 1910

Jack London usually sailed west whenever he left the Oakland Municipal Wharf, but on December 18, 1913, he headed east — because he could. Although the canal connecting the Oakland Estuary to San Leandro Bay had been completed in 1902, it wasn’t until the U.S. Army Corps of Engineers widened and deepened the canal in 1913 that it became navigable. Aboard the Roamer, a 30-foot yawl London bought used in 1910, Jack and his wife, Charmian, approached the Park Street Bridge. “Mate has to hustle for an hour or so to get Park St. Bridge open + we’re first boat that it ever opened for,” Charmian wrote in her diary. The Fruitvale and High Street bridges also swung open, and...
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The Delta’s Blooming Problem

Bright-green blotches of algae have been popping up all over the Delta since early summer, from Discovery Bay to the Stockton waterfront, befouling the air and poisoning the water with toxins that can sicken or even kill humans and animals. Veteran Delta watchers believe that this year’s harmful algal blooms may be the worst ever, and worry that some features of Governor Gavin Newsom’s recently released Water Resilience Portfolio for California will aggravate the problem. “We don’t have enough data to know if this is the worst year ever, because we haven’t been out there every single year for years and years monitoring,” says Meredith Howard, an environmental program manager with the Central Valley Regional Water Quality Control Board. “I...
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Makeover for Delta Weed Patch & Salt Trap?

What began as a project to convert a submerged Delta island into habitat for endangered native fish has morphed into a multi-benefit package with additional payoffs for water quality and recreation. The collaborative design process for the Franks Tract Futures project brought initially skeptical local stakeholders on board and is being hailed as a model for future initiatives. Yet major uncertainties remain as interested parties explore the challenges of implementing a complex redesign of a big chunk of the Delta. The proposed project would take a big shallow lake full of weeds, deepen some parts, fill in others with new lands and fish habitats, add beaches and recreational amenities, and stanch the spread of salt water from the ocean toward...
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wetland landscape photo
13
Sep

Better scientific preparation could help Delta water and environmental managers respond to droughts more effectively.

That’s one key takeaway from a review of environmental management and the use of science during the 2012-2016 drought commissioned by the Delta Science Program and published in the June 2020 issue of San Francisco Estuary and Watershed Science. “There are lots of mysteries about how to manage water to benefit species, agriculture, upstream and downstream users. I think science is going to be the best solution,” says lead author John Durand of UC Davis’ Center for Watershed Science. Durand and his team based their review on available reports and data, as well as discussions with agency staff, stakeholders and researchers. They focused on water management actions during the drought through the lens of four priorities identified by water managers:...
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