Science to action: Research informs management in the San Francisco Bay Delta

New findings on fish genetics, risk management, wastewater runoff, climate change impacts and more will help inform management in California’s Sacramento-San Joaquin/San Francisco Bay Delta. The research findings are a result of eight two-year projects by PhD students and postdocs, with funding from the Delta Stewardship Council and coordination of the fellowship program by California Sea Grant.

The Sacramento-San Joaquin Delta is a huge network of waterways that flow into San Francisco Bay. Home to over half a million people, the region is also a major water source for the state, and a major agricultural center. At the same time, the delta ecosystem supports many species and provides important ecosystem services, such as flood protection, to the people of the region.

California Sea Grant administers the Delta Science Fellowship program on behalf of the Delta Stewardship Council - Delta Science Program. The program funds high-quality science of relevance to resource management, and pairs young scientists with managers and other decision makers to develop research projects that directly inform management and policy development in the delta.

Since its establishment in 2003, the program has partnered 98 junior scientists with delta agency scientists and establishes research and community mentors to work on collaborative research projects applicable to delta policy and management.

“The Delta Science Fellowship accomplishes multiple goals—we are training the next generation of scientists, who are producing science that is, by design, directly informing resource management questions in the San Francisco-San Joaquin Bay-Delta. At the same time the fellowship promotes partnerships across agencies, research institutions and non-profit organizations,” says California Sea Grant Director Shauna Oh.

“This is a really unique fellowship program in that it links young scientists with both research and community mentors – ensuring relevant research for the challenging decisions that we face in the delta. And, past fellows from the program continue to provide enormous benefits to the region through their ongoing work with agencies, academia, and beyond,” says Delta Stewardship Council Lead Scientist John Callaway. 

Additional financial support for 2017-2019 Delta Science Fellows was provided by the State Water Contractors and the United States Bureau of Reclamation.

Applications for the 2020 Delta Science Fellowship are now open.

Project Summaries

Source characterization and biogeochemical consequences of wastewater and agricultural C, N, and P inputs to the Sacramento-San Joaquin Delta region
Joseph Fackrell, UC Santa Cruz

Over 200 million gallons per day of treated wastewater flow into the Sacramento-San Joaquin Delta from municipal treatment facilities. Although disinfected to prevent disease, this wastewater carries large amounts of carbon, nitrogen, phosphorous and sulfur compounds, which can affect water quality, algae growth, and the health of animals higher on the food web. This project defined the sources of these compounds, to help regulators and policymakers manage wastewater and agricultural discharge

Defining the architecture and recurrence interval for faults in the Sacramento-San Joaquin Delta: Assessing potential geohazards
Shannon Klotsko, San Diego State University

A major earthquake in the Sacramento-San Joaquin Delta region could have serious consequences for California’s water supply, as well as the ecology of the delta. The levees that protect the delta from saltwater inundation could be easily breached in an earthquake, and as sea level rises, the threats of flooding and saltwater intrusion become more serious. However, the area’s geology and seismic risks has not been well studied. This project created the first detailed fault map for the Sacramento-San Joaquin Delta

Revealing the invisible contributors to the diets of larval longfin smelt and striped bass in the San Francisco Estuary*
Michelle Jungbluth, San Francisco State University

Longfin smelt are a threatened species in the San Francisco Estuary ecosystem. Previous research suggests that the decline in this population in the estuary has been driven partly by a food shortage, but the diets of these fish have not yet been fully characterized. Using new molecular methods, this project compared the diet of larval longfin smelt to a similar fish which is not endangered. It identified differences in the fishes’ diets which may be contributing to these differences.

Monitoring Sacramento River winter-run Chinook salmon life history diversity, growth, and habitat use among varying hydroclimatic regimes
Pedro Morais, UC Berkeley

Sacramento River winter-run Chinook salmon have been endangered since 1994, and today their survival is threatened by drought and warmer conditions that could limit their ability to spawn. This project tackled two outstanding questions about winter-run salmon ecology. The first was how winter-run Chinook use different rearing habitats during drought and non-drought periods, and the second was to explore which habitats provide enhanced growth during drought and non-drought periods.

Perceptions of Risk and Management of the Delta Levee System
Pam Rittlemeyer, UC Santa Cruz

As a central hub of California’s water supply, transportation, and agricultural systems, the Sacramento-San Joaquin Delta is precariously positioned for change as a result of climate change, sea level rise, and its seismic activity. While there is an extensive body of scholarship about the Delta’s levees, the question remains of how the various perceptions of flood risk in the Delta align with the suite of potential adaptation measures. This project took a social science perspective to reconcile expert opinion, stakeholder interests, and landowner priorities.

Managing agricultural soils for carbon and water benefits in the California Delta: Understanding influences on decision-making and practice adoption of in-delta farmers
Jessica Rudnick, UC Davis

In the Sacramento-San Joaquin Delta, agriculture is the dominant land use. Improved soil health management can provide environmental benefits, such as carbon sequestration, water retention and filtration, subsidence reversal, and help agriculture become more resilient to climate change. Understanding the factors influencing farmers’ adoption of soil management practices is critical to building collaborative solutions to current and future climate and water challenges. This project investigated and analyzed the major factors contributing to decision-making and adoption of soil management practices by farmers in the delta

Evaluating contributions of hatchery-origin fish to conservation of endangered Sacramento River winter run Chinook salmon during a drought**
Neil Thompson, UC Santa Cruz

Hatchery-reared fish have been used to supplement endangered winter-run Chinook salmon in the upper Sacramento River since 1989. Intense drought in the past five years has led fisheries managers to substantially modify their hatchery protocols, but the impact of these practices is not fully understood. This project evaluated multiple aspects of how hatchery–reared fish contribute to natural production of winter-run Chinook salmon in the upper Sacramento River, to help fisheries managers deal with drought.

In search of refuge: Investigating the thermal life history of Delta Smelt through in-situ oxygen isotope ratio analysis of otoliths
Malte Wilmes, UC Davis

The Sacramento-San Joaquin Delta forms a vital link in California’s water supply but is also home to several species of endangered fish, causing significant conflict over the use of the limited fresh water resources for human and environmental flows. The endangered delta smelt is at the center of this conflict, and climate change is expected to put further pressure on the fish species. This study explored the ability of smelt to survive in warmer conditions by sheltering in cooler water during warmer period.

_{* Funded by the State Water Contractors (SWC)
** Funded by the US Bureau of Reclamation}