The State Water Resources Control Board's Role in Implementing the Delta Plan

California State Water Resources Control Board (SWRCB) | April 5th, 2011

The Delta Plan should identify the authorities of the State Water Board that may be employed to implement its goals, subgoals, and strategies. The State Water Board’s B

The Delta Plan should identify the authorities of the State Water Board that may be employed to implement its goals, subgoals, and strategies. The State Water Board’s Bay Delta Plan and Delta Strategic Workplan should be incorporated into the Delta Plan.

Treated Wastewater as a Multi-Benefit Groundwater Sustainability Project

Nature Conservancy | January 1st, 2019

The Arroyo Las Posas, a creek in Ventura County, is a good example of a stream supported by flows from a wastewater treatment plant (WWTP). These flows are a s

The Arroyo Las Posas, a creek in Ventura County, is a good example of a stream supported by flows from a wastewater treatment plant (WWTP). These flows are a significant factor in the basin’s water balance and support important GDEs. How this treated water is used in the future may therefore play a significant role in planning for the basin’s groundwater sustainability.

Tulare Lake Basin Hydrology and Hydrography: A Summary of the Movement of Water and Aquatic Species

U.S. Environmental Protection Agency (EPA) | April 12th, 2007

This report provides a summary of the historic and current hydrology of the Tulare Lake Basin (Basin) and describes past, present and potentiai future movement of water o

This report provides a summary of the historic and current hydrology of the Tulare Lake Basin (Basin) and describes past, present and potentiai future movement of water out of the Basin, and potential movement of bioiogical organisms and toxicants within and outside of the Basin. This study was initiated at the request of the U.S. Environmental Protection Agency (USEPA).

Undelivered Water: Fulfilling the CVPIA promise to Central Valley refuges

U.S. Bureau of Reclamation (USBR) | November 3rd, 2009

The 1992 Central Valley Project Improvement Act transformed California’s federal water management system by providing fish and wildlife a co-equal priority with other u

The 1992 Central Valley Project Improvement Act transformed California’s federal water management system by providing fish and wildlife a co-equal priority with other uses. In so doing, the Act mandated that the federal government establish a program, now known as the Refuge Water Supply Program (RWSP), to manage, secure, and deliver a reliable, clean water supply to serve the wetland habitat needs of nineteen federal, state, and private wildlife refuges in California’s Central Valley. The refuges protect a significant portion of the last remaining 5 percent of the historic Central Valley wetlands and provide birds of the Pacific Flyway habitat during critical periods when no other wetlands habitat may be available. In response to a request from OMB, the Bureau of Reclamation and the Fish and Wildlife Service established an Independent Panel to evaluate the performance of the RWSP component of the Central Valley Project Improvement Act.

Understanding Uncertainties in Future Colorado River Streamflow

American Meteorological Society (AMS) | January 1st, 2014

The Colorado River is the primary water source for more than 30 million people in the United States and Mexico. Recent studies that project streamf low changes in the Col

The Colorado River is the primary water source for more than 30 million people in the United States and Mexico. Recent studies that project streamf low changes in the Colorado River all project annual declines, but the magnitude of the projected decreases range from less than 10% to 45% by the mid-twenty-first century. To understand these differences, we address the questions the management community has raised: Why is there such a wide range of projections of impacts of future climate change on Colorado River streamflow, and how should this uncertainty be interpreted? We identify four major sources of disparities among studies that arise from both methodological and model differences. In order of importance, these are differences in 1) the global climate models (GCMs) and emission scenarios used; 2) the ability of land surface and atmospheric models to simulate properly the high-elevation runoff source areas; 3) the sensitivities of land surface hydrology models to precipitation and temperature changes; and 4) the methods used to statistically downscale GCM scenarios. In accounting for these differences, there is substantial evidence across studies that future Colorado River streamflow will be reduced under the current trajectories of anthropogenic greenhouse gas emissions because of a combination of strong temperature-induced runoff curtailment and reduced annual precipitation. Reconstructions of preinstrumental streamflows provide additional insights; the greatest risk to Colorado River streamf lows is a multidecadal drought, like that observed in paleoreconstructions, exacerbated by a steady reduction in flows due to climate change. This could result in decades of sustained streamflows much lower than have been observed in the ~100 years of instrumental record.

Water Quality Conditions in the Sacramento-San Joaquin Delta during 1995

California Department of Water Resources (DWR) | August 1st, 1999

Water year 1995 was a wet year, ending an eight-year period of predominantly dry and critically dry years.  After a relatively dry fall, January and March precipitation

Water year 1995 was a wet year, ending an eight-year period of predominantly dry and critically dry years.  After a relatively dry fall, January and March precipitation was heavy and produced flooding in the Central Valley.  By May 1, precipitation was 165% of average, snowpack water content was 215% af average, seasonal runoff was 170% of average, and reservoir storage was 110% of average. In 1995, the Net Delta Outflow Index (NDOI) was used to estimate Delta outflow, and the Sacramento and San Joaquin River Unimpaired Runoff indices were used to determine water year type for 1995.  Using these indices, water year 1995 was officially classified as wet on May 1, 1995.  All standards, including those in Water Right Decision 1485, as amended by the 1995 Water Quality Control Plan, were met in 1995. The entire 1995 calendar year was characterized by excess conditions, and both State Water Project and Central Valley Project water requirements were met as well as in-Delta consumptive uses.  Delta outflows were high throughout the year, and the calculated average monthly flows exceeded 80,000 cubic feet per second (CFS) during the peak outflow period (January through May), and 3,000 cfs during the minimum outflow period (July through November).

Water Stress and a Changing San Joaquin Valley

Public Policy Institute of California (PPIC) | March 1st, 2017

The San Joaquin Valley—California’s largest agricultural region, and an important contributor to the nation’s food supply—is in a time of great change and growing

The San Joaquin Valley—California’s largest agricultural region, and an important contributor to the nation’s food supply—is in a time of great change and growing water stress. Agriculture is a leading economic driver and the predominant water user. The region’s farms and related manufacturing businesses account for 25 percent of the valley’s revenues and 16 percent of local jobs—and 89 percent of annual net water use. The latest drought underscored valley agriculture’s vulnerability to water scarcity and long-term declines in groundwater reserves. The region has a greater abundance of productive farmland than local water supplies for irrigation. In most years since the mid-1980s, groundwater has been used faster than it is being replenished (“groundwater overdraft”). Over the past three decades, overdraft has averaged nearly 2 million acre-feet per year, or 13 percent of net water use. This has contributed to increased pumping costs, dry wells, sinking lands, and declining reliability of this vital drought reserve.

Water Supply and Habitat Resiliency for a Future Los Angeles River: Site-Specific Natural Enhancement Opportunities Informed by River Flow and Watershed-Wide Action

Nature Conservancy | December 15th, 2016

The mission of The Nature Conservancy is to conserve the lands and waters on which all life depends. As the Conservancy engages with the Los Angeles region, they are inve

The mission of The Nature Conservancy is to conserve the lands and waters on which all life depends. As the Conservancy engages with the Los Angeles region, they are investigating what it means to carry out this mission in the highly urbanized Los Angeles River ecosystem. As a starting point, it is known that the basic ecological principles of science apply to all environmental systems, regardless of their location. Therefore, the Conservancy is testing these principles by applying them in the Elysian Valley of the Los Angeles River and identifying habitat enhancement requirements, opportunities, and constraints. As a basic principle of ecological systems, a watershed’s hydrology determines the flow characteristics of its river system. These flows define what the biological characteristics of that river will be, which in turn determine what kinds of habitat enhancement projects will succeed at various locations along a river. The study of the Elysian Valley included one full year of multi-taxa biological surveys, a historical ecology investigation of the Elysian Valley, and a review of historic and existing hydrological and hydraulic conditions. Major findings of this study are: Multiple Flow Scenarios = Uncertainty: There are currently multiple visions for the flow characteristics of the Los Angeles River as a whole due to differing management priorities of the agencies and stakeholders that have governance over different aspects of this hydrologic system. Bringing the various hydrologic plans and possibilities for the watershed into a single integrated vision of system flow characteristics will allow certainty and clarity at the site level for the design of habitat projects anywhere in the River system, including the Conservancy’s study area. Flows Drive Biology: The study area currently has higher flood and much higher dry weather flow rates than its historic condition. These high flow rates are supporting and encouraging non-native and invasive species. This leads to a lower level of biological diversity and resiliency than what would exist under lower flow rates, particularly during dry weather conditions. Prioritize Complementary Habitats: Enhancing and increasing the amount of perennial riparian habitat in-stream alone will not create as much biological value as identifying complementary enhancement opportunities outside of the River channel in adjacent upper terrace floodplain and upland habitats (e.g. alluvial scrub, mulefat scrub, willow scrub, oak-sycamore woodland, sage scrub, and grassland). River Adjacent Land Use: Land uses adjacent to the River and throughout the watershed are a part of the solution and part of the Los Angeles River’s biological and hydrologic system. The landscaping and hydrology of these areas should be designed to provide a value-added role to the habitat functions of the Los Angeles River ecosystem. Next steps for advancing the discussion of habitat enhancement include working with local stakeholders and agencies to find consensus on a flow condition for the River and its Watershed as a whole. In the study area itself there are six complementary project opportunities that could be implemented in the near term to advance understanding of habitat enhancement for the Los Angeles River. These smaller, localized projects can be used as pilot projects for the complicated jurisdictional and regulatory processes that all future habitat projects will have to navigate. They will provide a manageable and controlled process that will bring the necessary agencies together to identify the most effective processes for future projects throughout the Los Angeles River ecosystem.

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

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

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.