Extreme hydrological changes in the southwestern US drive reductions in water supply to Southern California by mid century

Environmental Research Letters (IOP) | September 21st, 2016

The Southwestern United States has a greater vulnerability to climate change impacts on water security due to a reliance on snowmelt driven imported water. The State of C

The Southwestern United States has a greater vulnerability to climate change impacts on water security due to a reliance on snowmelt driven imported water. The State of California, which is the most populous and agriculturally productive in the United States, depends on an extensive arti cial water storage and conveyance system primarily for irrigated agriculture, municipal and industrial supply and hydropower generation. Here we take an integrative high-resolution ensemble modeling approach to examine near term climate change impacts on all imported and local sources of water supply to Southern California. While annual precipitation is projected to remain the same or slightly increase, rising temperatures result in a shift towards more rainfall, reduced cold season snowpack and earlier snowmelt. Associated with these hydrological changes are substantial increases in the frequency and the intensity of both drier conditions and ooding events. The 50 year extreme daily maximum precipitation and runoff events are 1.5–6 times more likely to occur depending on the water supply basin. Simultaneously, a clear de cit in total annual runoff over mountainous snow generating regions like the Sierra Nevada is projected. On one hand, the greater probability of drought decreases imported water supply availability. On the other hand, earlier snowmelt and signicantly stronger winter precipitation events pose increased flood risk requiring water releases from control reservoirs, which may potentially decrease water availability outside of the wet season. Lack of timely local water resource expansion coupled with projected climate changes and population increases may leave the area in extended periods of shortages.

Facilitating Adaptive Management in California’s Sacramento–San Joaquin Delta

University of California, Davis (UC Davis) | July 1st, 2017

Uncertainties in understanding ecosystems increase the risk that management will fail to achieve desired results. Adaptive management is a structured, iterative applicati

Uncertainties in understanding ecosystems increase the risk that management will fail to achieve desired results. Adaptive management is a structured, iterative application of science-based knowledge to reduce uncertainties and build flexibility into decision-making. However, adaptive management is more easily planned than implemented, and it is only beginning to be applied in the California’s Sacramento–San Joaquin Delta. We draw from two assessments of adaptive management in the Delta and examples of its use elsewhere to suggest how the process can be facilitated. Although a highly structured adaptive-management process may not always be needed, several elements are essential. Adaptive management should begin by clearly identifying the problem, goals, and objectives; recognizing uncertainties; identifying decision points and alternative approaches; recognizing when adjustments are needed and having the flexibility to make them; and considering societal and political constraints. Model complexity should be matched to that of the system and management needs; experiments can help unravel causal relationships. Monitoring, analyses, and syntheses require comprehensive data-management systems. More frequent and organized communications among scientists, managers, stakeholders, and decision-makers are necessary. We propose the establishment of an “Adaptive Management Team” to coordinate efforts across the management spectrum of the Delta and to provide guidance and link individual projects to shared approaches and experiences. Reliable long-term support will be needed to assess results of management actions, adjust approaches where improvement is likely, and strive toward the legislated goals of enhancing the Delta ecosystem while also providing reliable water supplies to much of California, and doing both these things in a manner that protects values of the Delta as a place where people live and work. 

Factors and Processes Affecting Delta Levee System Vulnerability

University of California, Davis (UC Davis) | December 1st, 2016

The authors appraised factors and processes related to human activities and high water, subsidence, and seismicity. Farming and drainage of peat soils over time has cause

The authors appraised factors and processes related to human activities and high water, subsidence, and seismicity. Farming and drainage of peat soils over time has caused a gradual sinking which contributed to internal levee failures. Although these subsidence rates have decreased with time, they still contribute to levee instability. Additional data is needed to assess spatial and temporal effects of subsidence caused by peat thinning and deformation. Since the mid-1970s large-scale, State investments in levee upgrades have increased conformance, however accounts continue to conflict on how these investments correspond to the numbers of failures. Both modeling and history suggest that the projected increases of high-flow frequency associated with climate change will increase levee-failures rates. Quantification of this increased threat requires further research. A reappraisal of seismic threats resulted in updated ground motion estimates for multiple faults and earthquake occurrence frequencies. The immediate seismic threat, liquefaction, is the sudden loss of strength due to an increase in the pressure of the pore fluid and corresponding loss of contact forces. However, levees damaged during an earthquake that do not immediately fail, may eventually breach. Consequences for future levee failure are estimated to cost up to billions of dollars. The analysis of future risks will benefit from more detailed descriptions of levee strength and upgrades, consideration of subsidence, climate change, and earthquake threats. Ecosystem benefits of levee habitats in this highly altered system are thin. Better recognition and coordination is needed among the creation of high value habitats, levee needs, costs, benefits of levee improvements, and breaches.  

Facts on the Water Rights Question in the Central Valley Project

California Farm Bureau (CFB) | March 11th, 1948

Feasibility Study for a Sacramento-San Joaquin Delta National Heritage Area

Delta Protection Commission (DPC) | June 4th, 2012

In Fall 2009, the California State Legislature passed a comprehensive package reforming governance of the Sacramento-San Joaquin Delta (Delta) and related aspects of stat

In Fall 2009, the California State Legislature passed a comprehensive package reforming governance of the Sacramento-San Joaquin Delta (Delta) and related aspects of statewide water management. In Section 85301 of Senate Bill X7-1 (Delta Reform Act of 2009), the Legislature charged the Delta Protection Commission (DPC) with developing: “A proposal to protect, enhance, and sustain the unique cultural, historical, recreational, agricultural, and economic values of the Delta as an evolving place....The Commission shall include in the proposal a plan to establish state and federal designation of the Delta as a place of special significance, which may include application for a federal designation of the Delta as a National Heritage Area.” This feasibility study has been undertaken in order to fulfill this legislative mandate, which upon acceptance of this study by the DPC, it will be submitted to a Delta Congressional Representative to introduce legislation to establish a Delta National Heritage Area (NHA). The study inventories and describes resources of the region which are supportive of the proposed NHA’s story and themes that make the area a place of national significance. The study also proposes how the NHA will be managed and organized to coordinate heritage area activities. Additionally, local groups who support the NHA are listed, along with letters of support; and organizations who are interested in potentially serving as partners on NHA activities are described, along with letters of partnership commitment. During the course of this process a separate effort was initiated to establish a Delta NHA. In January 2011, Senator Dianne Feinstein introduced legislation into the Senate, with companion legislation introduced by Congressman John Garamendi into the House of Representatives to designate a Delta NHA, with the DPC as the management entity. The DPC has been monitoring the progress of this legislation while continuing to work on this feasibility study. A NHA is a place designated by the United States Congress where natural, cultural, historical and recreational resources combine to form a cohesive, nationally-distinctive landscape arising from patterns of human activity shaped by geography. These areas tell nationally important stories about our nation and are representative of the national experience through both the physical features that remain and the traditions that have evolved within them. The DPC developed this study with a process that incorporated public involvement throughout its entirety. A variety of activities were undertaken to acquire stakeholder input, including: public meetings, public presentations, stakeholder interviews, public review memos, and project study team meetings.

Feather River Salmonid Habitat Improvement Project Proposed Mitigated Negative Declaration

California Department of Water Resources (DWR) | October 6th, 2022

An initial study/proposed mitigated negative declaration (IS/MND) has been prepared to assess the proposed project’s potential effects on the physical environment and t

An initial study/proposed mitigated negative declaration (IS/MND) has been prepared to assess the proposed project’s potential effects on the physical environment and the significance of those effects. Based on the analysis conducted in the IS, DWR has determined that the proposed project would not have any significant adverse effects on the environment because environmental commitments and mitigation measures would be implemented to reduce impacts to a less-than-significant level.

Federal Investments for the California Bay-Delta Region

U.S. Department of the Interior (DOI) | February 5th, 2014

The San Francisco Bay/Sacramento-San Joaquin Delta (Bay-Delta) region of California is an ecosystem of national significance. It is also the hub of the nation’s largest

The San Francisco Bay/Sacramento-San Joaquin Delta (Bay-Delta) region of California is an ecosystem of national significance. It is also the hub of the nation’s largest water delivery system—infrastructure that is the foundation for economic activity in the agricultural, industrial, and recreational sectors of the economy, and provides drinking water to a population of over 25 million Californians. This document is intended to provide an overview of the federal land and water programs in and around the Bay-Delta region, their purpose, options for future programs or actions, and an overview of the actions in which agencies are engaged already. Successful long term management of water resources and the environment to achieve the co-equal goals of the Bay Delta Conservation Plan (BDCP) and overall Delta sustainability requires continued improvement in managing California’s finite water supply. Contents I. Introduction II. Bay Delta-Big Picture: A Holistic Approach • State and Federal Integrated Water Management • Reducing Water Demand • Increasing Water Reliability and Supply • Improve Operational Efficiency and Transfers/Exchanges • Potential Federal Water and Ecosystem Management Actions III. Role of the Federal agencies • Department of the Interior Bureau of Reclamation U.S. Fish and Wildlife Service • Environmental Protection Agency • Department of Commerce National Oceanic and Atmospheric Administration • Army Corps of Engineers • Department of Agriculture Natural Resource Conservation Service U.S. Forest Service Rural Development Farm Services Agency Agriculture Research Service IV. Conclusion

Final Environmental Assessment Sacramento River Winter-Run Chinook Salmon Management Measures for Fisheries Managed under the Pacific Coast Salmon Fishery Management Plan

National Marine Fisheries Service (NMFS) | March 1st, 2018

Final Environmental Impact Statement: Long-Term Operation of the Central Valley Project and State Water Project Central Valley Project, California

U.S. Bureau of Reclamation (USBR) | November 15th, 2024

The United States Department of the Interior, Bureau of Reclamation (Reclamation) prepared this environmental impact statement (EIS) for the 2021 Endangered Species Act R

The United States Department of the Interior, Bureau of Reclamation (Reclamation) prepared this environmental impact statement (EIS) for the 2021 Endangered Species Act Reinitiation of Section 7 Consultation on the Long-Term Operation of the Central Valley Project (CVP) and State Water Project (SWP). This EIS is meant to inform the public and decision makers on potential federal actions by examining a range of reasonable alternatives and the potential effect on the environment. Reclamation manages the CVP. The California Department of Water Resources (DWR) manages the SWP. Collectively, the operation of the CVP and SWP provides flood control and navigation; delivers water to 30 million people; supports 4 million acres of agriculture; maintains 19 wildlife refuges on the Pacific Flyway; protects numerous iconic and endemic species such as Chinook salmon, coho salmon, steelhead, sturgeon, and smelt; generates 4.5 million megawatt hours of electricity; maintains water quality for beneficial uses in the San Francisco Bay/Sacramento–San Joaquin Delta Estuary (Bay-Delta); and supports recreation throughout Northern California. 

Final State Water Project Delivery Capability Report 2023

California Department of Water Resources (DWR) | July 31st, 2024

This Delivery Capability Report presents California Department of Water Resources (DWR) analysis of the State Water Project (SWP) system and provides important planning i

This Delivery Capability Report presents California Department of Water Resources (DWR) analysis of the State Water Project (SWP) system and provides important planning information for users of SWP water. The analysis provides information about how changing climate, regulatory, and operational considerations impact SWP delivery capability.