Delta Solutions

Overview

Named for its two central rivers, the Sacramento-San Joaquin Delta is the upper part of the San Francisco Bay, the largest estuary on the Pacific coast of the United States. The Delta provides California with an aquatic lifeline-irrigation for more than a million acres of farmland, water supply for 23 million residents, and critical habitat for migrating birds, two-thirds of the state's salmon and many other aquatic and terrestrial species.

The watershed of this large inland river delta includes nearly 40 percent of California and extends northward into Oregon. Much of the Delta's flows are currently diverted to millions of acres of farmland and residents, mostly upstream of the Delta, but also from pumps within the Delta. However, earthquakes, floods, droughts and non-native species are pushing the Delta into a crisis.

Researchers at the UC Davis Center for Watershed Sciences are at the forefront in providing policymakers with the scientific information and analysis that can help identify and evaluate solutions to preserve the Delta's many environmental and economic services. In addition to broad and focused studies, the Center also develops analysis to provide new insights for on-going strategic planning efforts and to better evaluate proposed future policy decisions.

Analytical tools include large-scale water resource optimization models, hydrodynamic models that evaluate water quality, ecological models to assess the ecosystem impacts of water operations or ecosystem restoration efforts, and economic models that examine costs and alternatives for land and water management strategies.

The Center for Watershed Sciences communicates results and provides tools to decision makers throughout the state and remains engaged in developing Delta solutions for the long term. Considerable effort goes to outreach and education. This includes working directly with legislative staff, local governments, water contractors and non-governmental organizations throughout California as well as various media outlets to disseminate our results.

A less visible, but perhaps more important method of translating our work into tangible change in the management of the Delta and California water in general is through our students. Most of the graduate students and research staff who work on our projects remain within California, working as agency, water contractor, consultant or non-governmental organization staff. In this indirect, long-term way, this project improves the technical capacity of these organizations.

The Delta Problem

Water and its management have been at the center of controversy in California for the past 150 years. Evolving and growing demands for water, coupled with changing climate and an aging water supply infrastructure, ensure that controversy will continue into the indefinite future. The increasing complexity of water resource issues in California requires increasingly sophisticated and innovative solutions.

The Sacramento-San Joaquin Delta lies at the head of the San Francisco Estuary and at the confluence of the Sacramento and San Joaquin Rivers. In the late 1800s and early 1900s the dynamic mosaic of tidal fresh water marsh and floodplain habitats of the Delta were drained and converted to farms, with levees keeping out the tides. Following land conversion, oxidation of the peat soils of the Delta led to a century of land subsidence, requiring continuous expansion of the levees to reduce flooding. Today, most of the Delta lies well below sea level--with some "islands" more than 25 feet below sea level--and is held in place by a network of 1100 miles of relatively weak levees.

"...a static, freshwater Delta is no longer sustainable, with the high likelihood of significant disruption to state water supplies."

For the past 70 years, the state and federal government has sought to maintain the Delta as a freshwater system through managed flows from upstream reservoirs and maintenance of the existing levee network. This policy stemmed from a desire to sustain agricultural activity within the Delta and exports of water through the Central Valley Project, the State Water Project, North Bay Aqueduct and the Contra Costa Canal. Exports from the Delta supply drinking water to 23 million Californians in the Bay Area and Southern California, and irrigation water to farms in the San Joaquin Valley. Recent work conducted by the UC Davis Center for Watershed Sciences and other institutions have demonstrated that a static, freshwater Delta is no longer sustainable, with the high likelihood of significant disruption to state water supplies. At least four hydrologic and geologic processes have the capacity to permanently change the static, freshwater condition of the Delta, principally by increasing the frequency of failure of the levee network. These include continued subsidence, sea level rise, changing inflows and earthquakes, which combine to cause local to widespread levee failure. At the same time, the native species of the Delta are undergoing rapid population declines. Several key fish species that are affected, in part, by Delta export activity, are listed or shortly will be listed as threatened or endangered species. This has already affected the ability of the state and federal government to export water from the Delta, with indications of greater restrictions in the future with substantial costs to the state’s economy.

Following the Hurricane Katrina disaster in New Orleans, and the court-mandated reductions in export pumping, the state began an intense planning effort to develop a sustainable future for the Delta. Two of these efforts—Delta Vision and the Bay-Delta Conservation Plan—are faced with the complex task of developing alternatives for managing the Delta in the future. These efforts are under intense political pressure from many, competing stakeholder groups.

Recognizing the compelling need for advanced technical and policy solutions for the Delta from an independent organization unaffiliated with any agency or stakeholder group, the Center for Watershed Sciences has initiated the Delta Solutions Program. The program brings together a team of research scientists, engineers and economists to test the environmental, economic and water supply performance of a range of future alternatives for the Sacramento-San Joaquin Delta. In addition, the group seeks to develop analytical tools designed to provide new insights for on-going strategic planning efforts and to better evaluate proposed future policy decisions. Finally, the group is committed to communicating its results and providing its tools to decisionmakers throughout the state and remaining engaged in developing Delta solutions for the long term.

The hallmark of the Delta Solutions Program will be the development or refinement of a analytical decision-support tools that better represent the Delta's complex problems. These include large-scale water resource optimization models, hydrodynamic models that evaluate water quality, ecological models to assess the ecosystem impacts of water operations or ecosystem restoration efforts, and economic models that examine costs and alternatives for land and water management strategies. Importantly, we are establishing this capability within a systematic and integrated analysis framework that will significantly improve the objective development and comparison of alternatives.

As part of our program, we are devoting considerable effort to outreach and education. This includes working directly with legislative staff, local governments, water contractors and non-governmental organizations throughout California as well as various media outlets to disseminate our results. A less visible, but perhaps more important method of translating our work into tangible change in the management of the Delta and California water in general is through our students. Most of the graduate students and research staff who work on our projects remain within California, working as agency, water contractor, consultant or non-governmental organization staff. In this indirect, long-term way, this project improves the technical capacity of these organizations.

The Center for Watershed Sciences

The mission of the UC Davis Center for Watershed Sciences is to house and foster research programs that resolve critical issues in watershed and water resource science. The center is engaged in a 10-year effort, the California Water Program, to develop solutions to present and future water resource issues in California. The center's California Water Program is currently involved in a broad range of activities throughout California. Center faculty, staff and student research efforts include evaluation of alternatives to restore salmon in the Klamath River and its tributaries, development of climate change adaptation strategies for management of Sierra Nevada hydropower reservoirs, alternatives for linking surface water and groundwater management in the Central Valley, development of new, innovative engineering and economic modeling approaches for management of water throughout California, and new approaches to resolving flood management. The signature effort of the California Water Program is the Delta Solutions Program.

View Moyle, P.B., Durand, J. and Jeffres, C., 2018. Making the Delta a better place for native fishes. Orange County Coast Keeper, Costa Mesa, California.