Geology topics

Research about upper San Francisco Estuary

Source-linked reports with geographic coverage including upper San Francisco Estuary.

2 recordsLinked to original sources

USGS2024

Management of tidal wetland restoration and fish in the upper San Francisco Estuary: Where are we now and how do we move forward? A summary of the 2023 Wetland Science Symposium

Tidal wetland restoration to benefit at-risk fish species in the Sacramento-San Joaquin Delta and Suisun marsh has gained momentum over the past decade, much of it in response to mitigation requirements for the State Water Project and Central Valley Project. In fall 2023, the Department of Water Resources and the State Water Contractors convened a symposium, entitled Delta-Suisun Tidal Wetland Restoration Symposium: State of the Science and Future Directions, to discuss the latest wetland restoration research and future directions. The symposium was held 10 years after the 2013 symposium “Tidal Marshes and Native Fishes in the Delta: Will Restoration Make a Difference?”, so served as an opportunity to follow up on the progress that has been made over the past decade. This paper synthesizes the key findings from the 2023 workshop. The paper begins with the historical context of wetland restoration in the Delta and Suisun marsh, then outlines the restoration process as it is currently implemented. It then describes the monitoring of tidal wetlands in terms of their capacity to support fish (capacity), the opportunity fish have to use the habitat (opportunity), and the realized functions provided when fish are actually using the site. Finally, the paper identifies priority science actions to advance our understanding and management of tidal wetland restoration sites. These actions include further research into fish habitat utilization, improved monitoring techniques, and enhanced adaptive management strategies. This list of information needs is intended to inform future monitoring of restoration sites, scientific studies, funding, and prioritization of wetland research.

California↗

USGS2022

Warming in the upper San Francisco Estuary: Patterns of water temperature change from five decades of data

Temperature is a key controlling variable from subcellular to ecosystem scales. Thus, climatic warming is expected to have broad impacts, especially in economically and ecologically valuable systems such as estuaries. The heavily managed upper San Francisco Estuary supplies water to millions of people and is home to fish species of high conservation, commercial, and recreational interest. Despite a long monitoring record (> 50 yr), we do not yet know how water temperatures have already changed or how trends vary spatially or seasonally. We fit generalized additive models on an integrated database of discrete water temperature observations to estimate long-term trends with spatio-seasonal variability. We found that water temperatures have increased 0.017°C yr −1 on average over the past 50 yr. Rates of temperature change have varied over time, but warming was predominant. Temperature increases were most widespread in the late-fall to winter (November to February) and mid-spring (April to June), coinciding with the winter development of juvenile Chinook salmon and spring spawning window of the endangered delta smelt. Warming was fastest in the northern regions, a key fish migration corridor with important tidal wetland habitat. However, no long-term temperature trends were detected in October and were only observed in some regions in May, July, and August. These results can help identify optimal areas for restoration or refugia to buffer the effects of a warming climate, and the methods can be leveraged to understand the spatiotemporal variability in climate warming patterns in other aquatic systems.

California↗