Prioritization of State Investments in Delta Levees and Risk Reduction Amendment to Existing Regulation

Delta Stewardship Council (Delta Council) | September 21st, 2023

Priority Margin Unit Stormwater Monitoring to Support Load Estimates of PCBs into San Leandro Bay and the Emeryville Crescent

San Francisco Estuary Institute (SFEI) | July 15th, 2022

The Priority Margin Unit Studies: The 2014 update of the RMP PCB Strategy called for a multi-year effort to implement the recommendations of the  PCB Synthesis Report (D

The Priority Margin Unit Studies: The 2014 update of the RMP PCB Strategy called for a multi-year effort to implement the recommendations of the  PCB Synthesis Report (Davis et al., 2014) including: 1. identifying margin units that are high priorities for management and monitoring, 2. developing conceptual models and mass budgets for margin units downstream of watersheds where management actions will occur, and 3. monitoring in these units as a performance measure. The goal of the effort was to inform the review and possible revision of the PCB TMDL and the reissuance of the Municipal Regional Permit for Stormwater (MRP).

Productive wetlands restored for carbon sequestration quickly become net CO2 sinks with site-level factors driving uptake variability

PLOS | March 25th, 2021

Inundated wetlands can potentially sequester substantial amounts of soil carbon (C) over the long-term because of slow decomposition and high primary productivity, partic

Inundated wetlands can potentially sequester substantial amounts of soil carbon (C) over the long-term because of slow decomposition and high primary productivity, particularly in climates with long growing seasons. Restoring such wetlands may provide one of several effective negative emission technologies to remove atmospheric CO2 and mitigate climate change. However, there remains considerable uncertainty whether these heterogeneous ecotones are consistent net C sinks and to what degree restoration and management methods affect C sequestration. Since wetland C dynamics are largely driven by climate, it is difficult to draw comparisons across regions. With many restored wetlands having different functional outcomes, we need to better understand the importance of site-specific conditions and how they change over time. We report on 21 site-years of C fluxes using eddy covariance measurements from five restored fresh to brackish wetlands in a Mediterranean climate. The wetlands ranged from 3 to 23 years after restoration and showed that several factors related to restoration methods and site conditions altered the magnitude of C sequestration by affecting vegetation cover and structure. Vegetation established within two years of re-flooding but followed different trajectories depending on design aspects, such as bathymetry-determined water levels, planting methods, and soil nutrients. A minimum of 55% vegetation cover was needed to become a net C sink, which most wetlands achieved once vegetation was established. Established wetlands had a high C sequestration efficiency (i.e. the ratio of net to gross ecosystem productivity) comparable to upland ecosystems but varied between years undergoing boom-bust growth cycles and C uptake strength was susceptible to disturbance events. We highlight the large C sequestration potential of productive inundated marshes, aided by restoration design and management targeted to maximise vegetation extent and minimise disturbance. These findings have important implications for wetland restoration, policy, and management practitioners.

Promoting atmospheric-river and snowmelt fueled biogeomorphic processes by restoring river-floodplain connectivity in California’s Central Valley

Springer | April 30th, 2015

Potential biogeomorphic benefits from intentional levee breaks and weir overflow on the managed floodplain-river system of California’s Sacramento and San Joaquin River

Potential biogeomorphic benefits from intentional levee breaks and weir overflow on the managed floodplain-river system of California’s Sacramento and San Joaquin River watershed (Central Valley) are discussed here. Prior to the nineteenth century, the system was characterized by natural levees alongside complex multichanneled rivers and tributaries, and geomorphic processes such as channel migration and avulsion, typical in lowland floodplain-river systems globally, dominated. Today, the floodplain-river system has been heavily modified with infrastructure such as levee embankments that disconnect floodplains from channels and diminish key processes of floodplain-river ecology. Unintentional levee breaks in river systems where floodplains have been developed for agriculture or urban uses still occur regularly (in a quarter of twentieth century years) and are sometimes catastrophic. Floodplain inundation, erosion, and sedimentation, the dominant geomorphic processes that occur during unintentional levee breaks, are flood risks in such embanked river systems. Climate and flood variability still dictate the frequency of unintentional levee breaks despite many decades of engineering. Of particular consequence are the so-called atmospheric-river (AR) storms. Since 1951, 81 % of breaks have occurred as a result of AR storms and flooding, while most of the rest occurred during snowmelt floods. Intentional levee breaks or planned weir overflows that are designed for floodplain restoration can facilitate a return towards more natural and dynamic biogeomorphic processes. In areas where room for flood-driven geomorphic processes is available on floodplains, local sediment scour and deposition near a levee break promote topographic diversity that enhances vegetation establishment and floodplain habitat. This chapter summarizes our current understanding of climate processes and flood variability that govern unintentional levee breaks or weir overflow. We also review examples of alternative flood management approaches in the Central Valley that promote processes necessary to restore or sustain lowland floodplain biogeomorphology. Future climate-driven changes in flood regime, such as enhanced flooding during winter months or more frequent atmospheric rivers, could be accommodated by additional intentional levee breaks or planned weir overflow for restoration. Implementation of these alternatives could be used to improve restoration policy and management of floods in embanked river floodplains.

Proposal for a Revised ITL and Expected Take for Adult Delta Smelt

Delta Stewardship Council (Delta Council) | July 29th, 2014

The 2008 USFWS Incidental Take Level (ITL) calculation determines the amount of annual delta smelt salvage allowed to be taken by the State Water Project (SWP) an

The 2008 USFWS Incidental Take Level (ITL) calculation determines the amount of annual delta smelt salvage allowed to be taken by the State Water Project (SWP) and Central Valley Project (CVP) during operating conditions expected under Reasonable and Prudent Alternative (RPA) thresholds. There is an ITL for adult and juvenile delta smelt. Using advances in statistical models, data sources, and overall improved knowledge of entrainment dynamics, we offer a robust approach for calculating a revised ITL and accompanying expected take method under the RPA for the SWP and CVP that remains protective of the species while providing improved flexibility for managing water operations.

Proposal for Calculating Cumulative Salvage Index Values Used For Estimating Take Likely to Occur under the USFWS Old and Middle River Flow RPA for Adult Delta Smelt

Delta Stewardship Council (Delta Council) | September 19th, 2014

The objectives of this paper are to provide a rationale why the United States Fish and Wildlife Service (USFWS) Incidental Take Statement should include more year

The objectives of this paper are to provide a rationale why the United States Fish and Wildlife Service (USFWS) Incidental Take Statement should include more years in its calculation of anticipated incidental take of adult delta smelt under the 2008 Biological Opinion with the Reasonable and Prudent Alternative (RPA) action to avoid jeopardy to the species and adverse modification of critical habitat and provide a statistical method by which this can be achieved.

Prospect Island Tidal Habitat Restoration Project: Admin Final Restoration Plan

California Department of Water Resources (DWR) | June 12th, 2014

This Prospect Island Tidal Habitat Restoration Project (Project) Draft Restoration Plan (Plan) describes the proposed actions needed to restore up to 1,600 acre (ac) of

This Prospect Island Tidal Habitat Restoration Project (Project) Draft Restoration Plan (Plan) describes the proposed actions needed to restore up to 1,600 acre (ac) of diked lands to tidal wetlands. The Project site is located in Solano County, in the northern Sacramento-San Joaquin River Delta (Delta) (Figure 1-1). Prospect Island falls under two ownerships: the approximately 1,300-ac northern property is owned by the California Department of Water Resources (DWR), and the southern, approximately 300-ac portion is owned by the Port of West Sacramento (Port). There are three privately owned properties contiguous to the site: the Stringer property, a small peninsula connected to the southeast margin of the DWR property; the Hall property, a small peninsula connected to the southeast margin of the Port property; and the Fahn property, actively farmed land north of the Project boundary. A privately operated marina, Arrowhead Harbor, is located at the northeastern corner of the site. With the exception of discussion of site topography (Section 4.3.3), three areal extents are used for the purposes of this Restoration Plan and interrelated environmental analyses of the Project. The Tidal Restoration Footprint is the area internal to the levees that would be subject to tidal action following restoration. The Diked Lands Project Area represents all diked lands that would be restored and potentially used to construct the Project, and extends outward to the high tide line on the exterior side of the levees. The Construction Project Area represents the Diked Lands Project Area plus all potential exterior in-water work areas.

Protocol for Closure of Delta Waterways

Office of Emergency Services | November 21st, 1997

This protocol describes the process for placing restrictions on vessel traffic on the San Joaquin/Sacramento Delta waterways during periods of high water levels and flood

This protocol describes the process for placing restrictions on vessel traffic on the San Joaquin/Sacramento Delta waterways during periods of high water levels and flood events that involve conditions of disaster or extreme peril to the safety of persons and property. Restrictions will provide for flood fight priorities and control of vessel wakes that may exacerbate levee erosion or overtopping.

Prototyping structured decision making for water resource management in the San Francisco Bay-Delta

Environmental Science & Policy (Elsevier) | May 2nd, 2024

A structured decision making (SDM) approach can help evaluate tradeoffs between conservation and human-benefit objectives by fostering communication and knowledge transfe

A structured decision making (SDM) approach can help evaluate tradeoffs between conservation and human-benefit objectives by fostering communication and knowledge transfer among stakeholders, decision makers, and the public. However, the process is iterative and completing the full process may take years. It can be difficult to initiate an SDM effort when problems seem insurmountable. Occasionally, SDM may not even be the best or correct approach for addressing the conservation problem at hand. We describe the implementation of an SDM process to help inform difficult decisions related to competing objectives. We convened a diverse stakeholder group from the largest estuary in the western United States; the San Francisco Bay and Sacramento-San Joaquin Delta (Bay-Delta). The stakeholder group consisted of representatives from local, state, and federal agencies, non-profit organizations, and recreational fishers. The stakeholder group agreed on a problem statement and identified four priority objectives related to Chinook salmon, delta smelt, water availability and reliability, and agricultural water use. Furthermore, they proposed 14 candidate management actions to achieve their objectives. The group then used existing quantitative models and data to evaluate trade-offs in proposed management actions to identify areas of agreement of proposed candidate actions. The clear communication of the problem statement and objectives among the stakeholder group, along with evaluation of tradeoffs and uncertainty via decision-support models suggest that a full SDM approach may work in the Bay-Delta. We further communicate lessons learned during our implementation of SDM to help guide future SDM efforts in the region and elsewhere. See also: Structured Decision Making Delta Stewardship Council June 2024 meeting report.

Pulse of the Delta 2011

San Francisco Estuary Institute (SFEI) | March 16th, 2011

Welcome to the first issue of the Pulse of the Delta: Monitoring and Managing Water Quality in the Sacramento – San Joaquin Delta, the new publication of the emerging D

Welcome to the first issue of the Pulse of the Delta: Monitoring and Managing Water Quality in the Sacramento – San Joaquin Delta, the new publication of the emerging Delta Regional Monitoring Program (RMP). This report is a direct response to Delta RMP stakeholders’ desire for an accessible water quality summary for the Delta that addresses important regional questions. Table of Contents: Did Contaminants Play a Role in the Pelagic Organism Decline? The Delta RMP: Re-thinking Water Quality Monitoring in the Delta Ammonia in the Delta: The science, implications for management How Delta Studies Have Reshaped Our Understanding Pyrethroid Insecticides Contaminants of Emerging Concern: Adapting to a Moving Target New Pesticides