Wetland geomorphology and tidal hydrodynamics drive fine‑scale fish community composition and abundance

Environmental Biology of Fishes (Springer) | January 19th, 2024

Where the Wild Things Aren't: Making the Delta a Better Place for Native Species

Public Policy Institute of California (PPIC) | April 5th, 2012

This report proposes a reconciliation approach for addressing 160 years of accumulated problems and for managing the Delta’s ecosystem in the future. Reconciliation eco

This report proposes a reconciliation approach for addressing 160 years of accumulated problems and for managing the Delta’s ecosystem in the future. Reconciliation ecology seeks to improve conditions for native species while recognizing that most ecosystems have been altered irrevocably by human use and will continue to be used to support human goals. Improving ecosystem conditions for native species must, therefore, happen in a context of continuing use of land and water by humans and continuing physical and biological change.

Will Tidal Wetland Restoration Enhance Populations of Native Fishes?

University of California, Davis (UC Davis) | July 31st, 2003

Restoration of tidal wetlands might enhance populations of native fishes in the San Francisco Estuary of California. The purpose of this paper is to: (1) review the curre

Restoration of tidal wetlands might enhance populations of native fishes in the San Francisco Estuary of California. The purpose of this paper is to: (1) review the currently available information regarding the importance of tidal wetlands to native fishes in the San Francisco Estuary, (2) construct conceptual models on the basis of available information, (3) identify key areas of scientific uncertainty, and (4) identify methods to improve conceptual models and reduce uncertainty. There are few quantitative data to suggest that restoration of tidal wetlands will substantially increase populations of native fishes. On a qualitative basis, there is some support for the idea that tidal wetland restoration will increase populations of some native fishes; however, the species deriving the most benefit from restoration might not be of great management concern at present. Invasion of the San Francisco Estuary by alien plants and animals appears to be a major factor in obscuring the expected link between tidal wetlands and native fishes. Large-scale adaptive management experiments (>100 hectares) appear to be the best available option for determining whether tidal wetlands will provide significant benefit to native fishes. Even if these experiments are unsuccessful at increasing native fish populations, the restored wetlands should benefit native birds, plants, and other organisms.

Wind Over San Francisco Bay and the Sacramento-San Joaquin River Delta: Forcing for Hydrodynamic Models.

San Francisco Estuary Institute (SFEI) | March 25th, 2019

The Ludwig wind model (Ludwig et al., 1991; Ludwig and Sinton, 2000) has been used to generate spaio-temporally varying wind inputs for hydrodynamic models of the San Fr

The Ludwig wind model (Ludwig et al., 1991; Ludwig and Sinton, 2000) has been used to generate spaio-temporally varying wind inputs for hydrodynamic models of the San Francisco Bay and Sacramento-San Joaquin River Delta (SFB-Delta) in recent projects at Deltares (Achete et al., 2015), at the United States Geological Survey (USGS; Martyr-Koller et al., 2017), and at San Francisco Esturary Institute (SFEI; Nuss et al., 2018). These projects all utilize hydrodynamic models in the Deltares suite of software known as DFlow (e.g., Deltares, 2019), and the wind inputs to DFlow are specied hourly on a 1.5 km x 1.5 km grid.

Working Draft Scientific Basis Report for New and Revised Flow Requirements on the Sacramento River and Tributaries, Eastside Tributaries to the Delta, Delta Outflow, and Interior Delta Operations

California State Water Resources Control Board (SWRCB) | October 14th, 2016

This working draft Scientific Basis Report (Report) is being prepared to support the update of the Bay-Delta Plan’s protection of fish and wildlife beneficial uses in t

This working draft Scientific Basis Report (Report) is being prepared to support the update of the Bay-Delta Plan’s protection of fish and wildlife beneficial uses in the Sacramento River watershed and related areas, known as Phase II.1 This update considers four categories of requirements: (1) new inflow requirements for the Sacramento River, its tributaries, and eastside tributaries to the Delta; (2) changes to Delta outflow requirements; (3) new and modified interior Delta flow requirements; and (4) new requirements for cold water habitat. A comprehensive regulatory approach is needed that protects Bay-Delta fish and wildlife throughout their migratory range, and that better integrates the regulatory framework addressing inflows, outflows, and water project operations. Such a framework will help avoid overreliance on one stream to meet flow and other water quality requirements by providing necessary flows on multiple tributaries to ensure suitable habitat and migratory pathways upstream of the Bay-Delta. Another goal is to employ a strategy that provides for timely action, flexibility, and integration with other planning, science, restoration, and regulatory efforts so action can be taken before imperiled species in the watershed are no longer able to be restored.

Workshop on Delta Outflows and Related Stressors Panel Summary Report

Delta Stewardship Council (Delta Council) | May 15th, 2014

This report was prepared as part of the State Water Resources Control Board’s (“Board”) process of developing and implementing updates to the Bay-Delta Plan and flo

This report was prepared as part of the State Water Resources Control Board’s (“Board”) process of developing and implementing updates to the Bay-Delta Plan and flow objectives to protect beneficial uses in the Bay-Delta Watershed. The focus of this report is Delta outflows and related stressors. The report is based upon reading extensive background materials selected by the Delta Science Program as well as materials identified by individual Panel members to be relevant, a two-day public meeting that included a number of presentations and during which public comments were received by the Panel, review of some of the materials provided during and after the meeting, and the Panel’s internal discussion and deliberations. The Board conducted a review of the current 2006 Bay-Delta Plan in 2009 and determined that Delta outflows and other requirements for the protection of fish and wildlife beneficial uses should be considered for revision. “Delta Outflows and Related Stressors” was further identified by the Delta Science Program as one of four topics emerging from a series of Board workshops in 2012 for which additional workshops should be conducted to provide input on the best available scientific information. Delta outflows and their management have been the subject of extensive scientific and management discussion for decades. A benchmark in this discourse is the report from a series of technical workshops facilitated by Dr. Jerry Schubel (Schubel et al. 1993). Schubel notes in the preface to that report that estuarine standards are required to protect the estuarine ecosystem from “further degradation” until “debate and disagreement over the relative importance of the benefits of low salinity habitat and therefore of flow, on the one hand, and of the liabilities of the physical diversion of a portion of that flow and the associated processes of entrainment of organisms, on the other,” can be resolved with a degree of scientific certainty acceptable to the Board. To some extent, this Panel has been asked to revisit whether standards for Delta outflow are still required, and to identify the degree of scientific certainty regarding the importance of Delta outflow to the ecosystem relative to other stressors.

Workshop on the Interior Delta Flows And Related Stressors Panel Summary Report

Delta Stewardship Council (Delta Council) | August 6th, 2014

On April 16 and 17, 2014, the Delta Science Program convened an expert Panel (the Panel) and a workshop to identify the best available science to inform the State Water R

On April 16 and 17, 2014, the Delta Science Program convened an expert Panel (the Panel) and a workshop to identify the best available science to inform the State Water Resources Control Board’s (the Board) decisions regarding interior Delta flow requirements to protect beneficial uses of water in the San Francisco Bay/Sacramento-San Joaquin Estuary (Bay-Delta Plan). This workshop and others were convened to provide advice to the Board on issues important to updating the 2006 Bay Delta Plan. At the workshop, the Panel (consisting of the authors of this report) heard presentations from a variety of experts on Delta flows and on species and ecological responses to flow. The Panel was also provided with a selection of scientific reports relevant to the effects of interior Delta flows on fish and their environment in the Delta. This report is informed by both the written and oral information provided to the Panel as well as by other publications that the Panel felt were necessary to satisfy its charge.  The Panel did not make a thorough independent search of the literature on the Sacramento-San Joaquin Delta to determine if there were additional publications that were relevant to its charge. In this report we summarize what is known about the direct and indirect relationships between interior Delta flows and listed fish species. We then use this knowledge to address a set of specific questions posed by the Delta Science Program and the Board.

Workshop report—Earthquakes and High Water as Levee Hazards in the Delta

Delta Stewardship Council (Delta Council) | September 30th, 2016

Earthquakes and high water as hazards to Delta levees were reviewed in a seven-hour workshop organized by the Delta Independent Science Board and held at the campus of th

Earthquakes and high water as hazards to Delta levees were reviewed in a seven-hour workshop organized by the Delta Independent Science Board and held at the campus of the University of California, Davis. Earthquake hazards in the Delta were described in terms of ground motions from Bay Area earthquakes, infrequent earthquake recurrence on faults beneath the Delta, and levee fills prone to earthquake-induced liquefaction. Large uncertainties attend all these seismic elements of levee hazard. Those uncertainties, according to presentations in the workshop, include whether the Delta ground motions previously computed for Bay Area earthquakes were too large.  Hazards from high water were deemed greatest from the confluence of high river discharge, wind-driven surge and waves, and high tides. Major risk assessments have used available data on these hazards without mandates to advance the science. Research needs and opportunities identified in the workshop include expanded observations of Delta ground motions, improved estimates of geologically recent displacement on faults beneath the Delta, further identification of liquefiable materials and mechanisms beneath levees, continued airborne measurements of land-level change, updated mapping of the contracting area of remaining peat, and fuller documentation of past levee failures. Recurring assessments of earthquake hazards and climate change provide precedents for periodic reappraisal of Delta levee risk. The workshop brought together different parts of the diverse community of Delta levee specialists. Positive responses to the workshop suggest that it served levee specialists and outsiders alike.

Workshop report—Earthquakes and High Water as Levee Hazards in the Sacramento-San Joaquin Delta

Delta Stewardship Council (Delta Council) | September 30th, 2016

Yolo Bypass Juvenile Salmon Utilization Study 2016— Summary of Acoustically Tagged Juvenile Salmon and Study Fish Releases, Sacramento River, California

U.S. Geological Survey (USGS) | September 12th, 2017

The Yolo Bypass is a flood control bypass in Sacramento Valley, California. Flood plain habitats may be used for juvenile salmon rearing, however, the potential value of

The Yolo Bypass is a flood control bypass in Sacramento Valley, California. Flood plain habitats may be used for juvenile salmon rearing, however, the potential value of such habitats can be difficult to evaluate because of the intermittent nature of inundation events. The Yolo Bypass Juvenile Salmon Utilization Study (YBUS) used acoustic telemetry to evaluate the movements and survival of juvenile salmon adjacent to and within the Yolo Bypass during the winter of 2016. This report presents numbers, size data, and release data (times, dates, and locations) for the 1,197 acoustically tagged juvenile salmon released for the YBUS from February 21 to March 18, 2016. Detailed descriptions of the surgical implantation of transmitters are also presented. These data are presented to support the collaborative, interagency analysis and reporting of the study findings.