Restoring Habitat with Science and Society in Mind

Delta Stewardship Council (Delta Council) | April 8th, 2014

This Issue Paper, authored by Jessica Davenport, the Council's Program Manager for Ecosystem Restoration and Land Use, is entitled Restoring Habitat with Science and Soci

This Issue Paper, authored by Jessica Davenport, the Council's Program Manager for Ecosystem Restoration and Land Use, is entitled Restoring Habitat with Science and Society in Mind.  The purpose of the 22-page paper is to survey restoration activities in the Delta; describe the needs, progress and opportunities related to restoration; and propose key areas of focus for the Delta Stewardship Council and other agencies to advance habitat restoration. Some of the areas of focus for Council staff for the next two years include: Continue to provide early consultation on habitat restoration projects that are Covered Actions under the Delta Plan in order to advise project proponents on using best available science and adaptive management and avoiding or reducing conflicts with existing uses, where feasible. Report on habitat performance measures by December 2014 and again in December 2015. Work with others to complete at least one of the landscape-scale conceptual models and associated landscape habitat metrics for the priority habitat restoration areas. Enagage Delta Plan Interagency Implementation Committee members in discussions of challenges and potential solutions related to land acquistion and permit coordination.

Restoring the Heart of a Healthy Estuary: A Review of Restoration in the Sacramento–San Joaquin Delta and Suisun Marsh

Publisher not available | December 19th, 2025

The restoration of native species-dominated ecosystems is critical for improving ecosystem health and meeting policy goals in the Sacramento–San Joaquin Delta and Suisu

The restoration of native species-dominated ecosystems is critical for improving ecosystem health and meeting policy goals in the Sacramento–San Joaquin Delta and Suisun Marsh (upper San Francisco Estuary, collectively), one of the largest estuarine systems in North America. To accomplish large-scale restoration in this heavily altered system, a variety of projects, programs, and motivations inform restoration planning and implementation. Chapter 4 of the Delta Plan synthesizes restoration goals across these efforts to produce comprehensive ecosystem restoration targets of between 60,000 and 80,000 acres across seven ecosystem types by 2050, but a comprehensive review of restoration progress and planning to date is needed. To fill this gap, this paper analyzes the current state of ecosystem restoration in the upper San Francisco Estuary in the context of the Delta Plan targets. We review current scientific and management literature and implementation approaches, and synthesize acreage totals across completed, in-progress, and planned projects for four ecosystem types where substantial development of restoration in the system has occurred: tidal wetland, non-tidal wetland, riparian, and floodplain. We find that tidal wetland restoration has progressed more rapidly than other ecosystem types, motivated by mitigation requirements related to the federal Endangered Species Act. Across all ecosystem types, we identify both promising progress and clear needs for accelerated planning and implementation of restoration projects to meet Delta Plan 2050 targets, and discuss ongoing needs related to science, funding, and implementation.

Reversal in estuarine sand supply driven by Holocene sea level rise: A model for sand transport in large structural estuaries, San Francisco Bay, California, USA

Elsevier | July 26th, 2024

Coastal sand supply is a critical component of shoreline stability in the face of modern threats to coastal zones such as sea level rise or anthropogenic sediment extract

Coastal sand supply is a critical component of shoreline stability in the face of modern threats to coastal zones such as sea level rise or anthropogenic sediment extraction. Understanding the natural and anthropogenically perturbed dynamics of coastal systems has become a pressing challenge for coastal communities, such as the San Francisco Bay area in the United Sates, a large structurally controlled estuary system where stakeholders seek to balance the extraction of coastal sand resources for economic use and ensure sufficient sand supply for sustaining natural coastal environments. Developing accurate and comprehensive models of sand inputs and transport pathways in different types of coastal systems is imperative to balancing these competing needs. While estuarine sediment transport has been well-studied in many systems globally, structurally controlled estuaries in tectonically active settings have received relatively less attention. The prevailing hypothesis for sediment transport through San Francisco Bay describes active input and transport of sand from a large integrated regional catchment, through multiple subembayments, and out to Pacific coast beaches; a model contrary to prevailing understanding of highstand estuarine sediment transport in most settings. We test this model by applying comprehensive sand provenance analysis to surface and near-surface sand deposits in and around San Francisco Bay coupled with sand residence time data from optically stimulated luminescence (OSL) dating. New provenance results include sand petrography modal abundances, bulk geochemistry, and U-Pb detrital zircon geochronology from 27 Holocene samples throughout the San Francisco Bay region. Collectively, these new results highlight marked sediment provenance and residence time differences between San Francisco Bay structural subembayments. In particular, distinct compositional differences and OSL ages exist between sand in the bayhead region of the estuary (OSL ages ca. 4 ka; Sacramento River/local provenance) and sand from the more distal bay regions and the Pacific coast (OSL ages ca. 1 ka; integrated Sierra Nevada provenance). These provenance differences better support a revised sand input and transport model with disconnected depocenters across three structurally restricted subembayments from bayhead to the Pacific coast. New data suggest that at present the bayhead region receives limited supply from the Sacramento-San Joaquin Delta drainage with subsidiary supply from local circum-bay drainages. Sand deposited in the region from the Pacific coast through the inlet (Golden Gate) and into the estuary consists of a combination of tidal winnowing and reworking of “relic” sand from lowstand periods combined with sand eroded from Pacific coast sea cliffs, and sand supply from local Coast Range drainages. These results suggest that sand is likely not transported directly to the Pacific coast from the Sacramento-San Joaquin Delta under modern conditions. Moreover, it is likely that structural constrictions between the main estuary and outer coast and between estuary subembayments cause abrupt cessation of sediment input from the main regional drainage during marine flooding, a feature likely common to large structurally controlled estuaries globally. This revised model for San Francisco Bay sand transport illustrates the need for research targeted at interpreting natural sand transport pathways in coastal systems where coarse sediment supply is a sustainability concern.

Review of 2018 Ocean Salmon Fisheries Stock Assessment and Fishery Evaluation Document for the Pacific Coast Salmon Fishery Management Plan

Pacific Fishery Management Council | February 11th, 2019

Review of and recommendations for monitoring contaminants and their effects in the San Francisco Bay−Delta

University of California, Davis (UC Davis) | December 3rd, 2019

Legacy and current-use contaminants enter into and accumulate throughout the San Francisco Bay−Delta (Bay−Delta), and are present at concentrations with known effects

Legacy and current-use contaminants enter into and accumulate throughout the San Francisco Bay−Delta (Bay−Delta), and are present at concentrations with known effects on species important to this diverse watershed. There remains major uncertainty and a lack of focused research able to address and provide understanding of effects across multiple biological scales, despite previous and ongoing emphasis on the need for it. These needs are challenging specifically because of the established regulatory programs that often monitor on a chemical-by-chemical basis, or in which decisions are grounded in lethality-based endpoints. To best address issues of contaminants in the Bay−Delta, monitoring efforts should consider effects of environmentally relevant mixtures and sub-lethal impacts that can affect ecosystem health. These efforts need to consider the complex environment in the Bay−Delta, including variable abiotic (e.g., temperature, salinity) and biotic (e.g., pathogens) factors. This calls for controlled and focused research, and the development of a multi-disciplinary contaminant monitoring and assessment program that provides information across biological scales. Information gained in this manner will contribute toward evaluating parameters that could alleviate ecologically detrimental outcomes. This review is a result of a Special Symposium convened at the University of California−Davis (UCD) on January 31, 2017 to address critical information needed on how contaminants affect the Bay−Delta. The UCD Symposium focused on new tools and approaches for assessing multiple stressor effects to freshwater and estuarine systems. Our approach is similar to the recently proposed framework laid out by the U.S. Environmental Protection Agency (USEPA) that uses weight of evidence to scale toxicological responses to chemical contaminants in a laboratory, and to guide the conservation of priority species and habitats. As such, we also aimed to recommend multiple endpoints that could be used to promote a multi-disciplinary understanding of contaminant risks in Bay−Delta while supporting management needs.

Review of Delta Conveyance Project Benefit-Cost Analysis: Implications for Decision-Makers and Financing

University of the Pacific, Center for Business and Policy Research | June 24th, 2024

Review of North Delta Salmon Out-Migration Study

CALFED | January 23rd, 2008

This document is a review of the North Delta Salmon Out-Migration Study (NDSOS) proposed to the California Department of Water Resources (DWR) by a group of PIs l

This document is a review of the North Delta Salmon Out-Migration Study (NDSOS) proposed to the California Department of Water Resources (DWR) by a group of PIs lead by Jon Burau of the USGS. To carry out this review, the CALFED Science program, acting at the request of DWR and the PIs, convened a panel that was given a substantial written proposal describing the study. In addition to the written proposal, the PIs gave a series of presentations to a majority of the panel members at a public workshop held on January 10, 2008. The presentations provided many details about the proposed study that were not included in the written proposal. The panel was charged by CALFED to: “.... make recommendations concerning, and oversee incorporation of modifications to, the proposed study to ensure that, when funded, executed, and analyzed, the proposed investigation will provide the best-available science when characterizing the hydrodynamics and movement of out-migrating salmon smolts in the north Delta region in response to several alternate regional configurations.” This report is the panel’s response to that charge. In the sections that follow, we start by describing those aspects of the proposal that the panel found would work well or were strong positives. We follow this with a critique of perceived shortcomings of the proposal and a set of recommendations for possible changes to the proposed work that would improve the proposed study. These recommendations were based on the information in the written proposal provided to the panel and on the presentations made at the public workshop.

Review of Research on the Sacramento-San Joaquin Delta as an Evolving Place

Delta Stewardship Council (Delta Council) | May 11th, 2017

Research on the social and natural processes that sustain the unique values of the Delta as an evolving place is sparse and sporadic. We found seven research projects and

Research on the social and natural processes that sustain the unique values of the Delta as an evolving place is sparse and sporadic. We found seven research projects and no established research programs directly aimed at developing an understanding of the processes supporting the Delta as an evolving place. Far more research occurs on other Delta topics, such as water flows, contaminants and nutrients, and at risk species. Nor did we find evidence that research in these other areas is identifying natural processes that could protect and enhance the values of the changing Delta. We therefore recommend an expanded, sustained commitment to research on the unique cultural, recreational, natural resource, and agricultural values of the Delta as an evolving place. The level of effort could resemble that in other Delta subject areas. Priority should be given to research that supports achieving the coequal goals in a manner that protects and enhances these unique values.

Review of Science Used to Estimate Water Supply Reliability Involving the Delta

Delta Stewardship Council (Delta Council) | April 3rd, 2018

Review of SWRCB’s “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”

Delta Stewardship Council (Delta Council) | February 23rd, 2017

Insightful, informative, well-illustrated, clearly written—these are among our overall impressions of “Working Draft Scientific Basis Report for New and Revised Flow

Insightful, informative, well-illustrated, clearly written—these are among our overall impressions of “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”. The comments below focus on recommended improvements. In particular, we recommend clarifying, and further justifying scientifically, the proposed use of percent of “unimpaired flow” as the main basis for establishing an annual environmental water budget. We also suggest presenting a further review of cold-water management, a deeper analysis of non-flow stressors, additional consideration of near-term responses to climate change, and elaboration of how regulations managed adaptively may improve scientific understanding of environmental flows.