Letter to State Water Board re: Flow Criteria that use Percent of Unimpaired Flow

Delta Stewardship Council (Delta Council) | May 22nd, 2012

The proposed use of percent of unimpaired flow is a step toward improving the outlook for fish and other wildlife utilizing the San Joaquin River and its tributaries. Fal

The proposed use of percent of unimpaired flow is a step toward improving the outlook for fish and other wildlife utilizing the San Joaquin River and its tributaries. Fall-run Chinook salmon are likely to benefit from February-through-June flows that are more natural in timing and variability than current flows. Compared with the existing maze of flow standards for the San Joaquin River and its tributaries, unimpaired flow comes closer to approximating natural flow, and it does so more transparently. Caveats include: (1) flow is but one of many stressors affecting fish and wildlife; (2) the choice of flow criteria and metrics needs to serve the broader needs of ecosystems as well as individual species; (3) a chosen percentage of unimpaired flow may fall short of the minimum needed by fish and wildlife in some years; and (4) such critical years are likely to become more common as Sierra Nevada snowpacks diminish as a consequence of climate change. This qualified endorsement is based on our reading of the “Technical Report on the Scientific Basis for Alternative San Joaquin River Flow and Southern Delta Salinity Objectives” (State Water Resources Control Board, February 2012).

Listen to the River: An Independent Review of the CVPIA Fisheries Program

U.S. Bureau of Reclamation (USBR) | December 12th, 2008

In 1992 Congress directed the Department of Interior to develop and implement a program that makes “all reasonable efforts” to ensure and sustain on a long-term basis

In 1992 Congress directed the Department of Interior to develop and implement a program that makes “all reasonable efforts” to ensure and sustain on a long-term basis a doubling of the number of naturally produced anadromous fish in Central Valley rivers and streams by 2002. Doubling did not happen by the legislative goal of 2002, or by 2008, nor is it likely to ever occur unless renewed commitments and improvements are made to the CVPIA program. The specific “doubling” mission itself may make little scientific or policy sense, especially within the time frames demanded. Yet it is also far from clear that the agencies have done what is possible and necessary to improve freshwater conditions to help these species weather environmental variability, halt their decline and begin rebuilding in a sustainable way. A number of the most serious impediments to survival and recovery are not being effectively addressed, especially in terms of the overall design and operation of the Central Valley Project system. Underlying this independent review of the CVPIA anadromous fish program, asked for by the federal agencies, is the question why the CVPIA program has not been successful in achieving its mission. In this report, we identify scientific, institutional and programmatic obstacles to the success of the CVPIA, drawing conclusions from the information provided. Based on these conclusions, we make recommendations to Reclamation and the Service on how these obstacles might be overcome.

Local hydraulics influence habitat selection and swimming behavior in adult California Central Valley Chinook salmon at a large river confluence

Fisheries Research (Elsevier) | February 2nd, 2023

Long-Term Central Valley Project Operations Criteria and Plan CVP-OCAP

U.S. Bureau of Reclamation (USBR) | July 1st, 2004

This document has been prepared to serve as a baseline description of the facilities and operating environment of the Central Valley Project (CVP) and State Water Project

This document has been prepared to serve as a baseline description of the facilities and operating environment of the Central Valley Project (CVP) and State Water Project (SWP). The Central Valley Project - Operations Criteria and Plan (CVP-OCAP) identifies the many factors influencing the physical and institutional conditions and decision-making process under which the project currently operates. Regulatory and legal requirements are explained, alternative operating models and strategies described. The immediate objective is to provide operations information for the Endangered Species Act, Section 7, consultation. The long range objective is to integrate CVP-OCAP into the proposed Central Valley document.  It is envisioned that CVP-OCAP will be used as a reference by technical specialists and policymakers in and outside Bureau of Reclamation (Reclamation) in understanding how the CVP is operated. The CVP-OCAP includes numeric and nonnumeric criteria and operating strategies. Emphasis is given to explaining the analyses used to develop  typical operating plans for simulated hydrologic conditions. All divisions of the CVP are covered by this document, including the Trinity River Division, Shasta and Sacramento River Divisions, American River Division, Delta Division, West San Joaquin Division, and Friant Division.

Losses of Sacramento River Chinook Salmon and Delta Smelt to Entrainment in Water Diversions in the Sacramento-San Joaquin Delta

University of California, Davis (UC Davis) | June 30th, 2008

Pumping at the water export facilities in the southern Sacramento-San Joaquin Delta kills fish at and near the associated fish-salvage facilities. Correlative analyses of

Pumping at the water export facilities in the southern Sacramento-San Joaquin Delta kills fish at and near the associated fish-salvage facilities. Correlative analyses of salvage counts with population indices have failed to provide quantitative estimates of the magnitude of this mortality. I estimated the proportional losses of Sacramento River Chinook salmon (Oncorhynchus tshawytscha) and delta smelt (Hypomesus transpacificus) to place these losses in a population context. The estimate for salmon was based on recoveries of tagged smolts released in the upper Sacramento River basin, and recovered at the fish-salvage facilities in the south Delta and in a trawling program in the western Delta. The proportion of fish salvaged increased with export flow, with a mean value around 10% at the highest export flows recorded. Mortality was around 10% if pre-salvage losses were about 80%, but this value is nearly unconstrained. Losses of adult delta smelt in winter and young delta smelt in spring were estimated from salvage data (adults) corrected for estimated pre-salvage survival, or from trawl data in the southern Delta (young). These losses were divided by population size and accumulated over the respective seasons. Losses of adult delta smelt were 1–50% (median 15%) although the highest value may have been biased upward. Daily losses of larvae and juveniles were 0–8%, and seasonal losses accumulated were 0–25% (median 13%). The effect of these losses on population abundance was obscured by subsequent 50-fold variability in survival from summer to fall.

Lower Basin Alternative for the Post-2026 Coordinated Operation of the Colorado River Basin

Southern Nevada Water Authority (SNWA) | March 6th, 2024

Making the Most of Water for the Environment: A Functional Flows Approach for California’s Rivers

Public Policy Institute of California (PPIC) | August 25th, 2020

In California, water and land management activities have substantially altered river flows and degraded river channels and their floodplains. The result has been a precip

In California, water and land management activities have substantially altered river flows and degraded river channels and their floodplains. The result has been a precipitous decline in native fish populations, including the collapse of valued salmon fisheries, and widespread imperilment of freshwater biodiversity. Environmental flows—flows in rivers and streams necessary to sustain ecosystem health—are essential to reversing these trends. Yet many rivers in California lack environmental flows. And for those rivers with such protections, environmental flows are typically established at static minimum levels, which fail to preserve the natural seasonal and interannual variability of flow that sustains healthy ecosystems. A new approach to managing environmental water is needed. 

Managing diversions in unregulated streams using a modified percent-of-flow approach

Freshwater Biology (Wiley) | August 22nd, 2017

In Mediterranean-type river systems stream flows are naturally low in summer and autumn. This pattern is often exacerbated by over-exploitation of water resources during

In Mediterranean-type river systems stream flows are naturally low in summer and autumn. This pattern is often exacerbated by over-exploitation of water resources during the dry season, which has implications for managing flows for both environmental and human needs. Mediterranean systems are characterised by strong inter- and intra-annual variability with almost all precipitation occurring in winter months followed by summer droughts with little or no rainfall, and extreme year-to-year variation ranging from intense winter storms to year-round drought (Gasith & Resh, 1999; Power, Kupferberg, Cooper, & Deas, 2015; Power, Parker, & Dietrich, 2008). The seasonal pattern of precipitation in Mediterranean climatic regions results in water availability and demand being out-of-phase; precipitation and runoff occur (almost exclusively) in winter when human demands are lowest, and precipitation is virtually non-existent in summer months when human demand is greatest (Kondolf & Batalla, 2005; Merenlender & Matella, 2013). As a result, rivers in Mediterranean climates tend to have a high degree of alteration with streamsdiverted and dammed to provide scarce water for human use (Kondolf, Podolak, & Grantham, 2013; Marr et al., 2009; Moyle, 2013). While the biophysical responses to alterations of land use, vegetation and hydrology are similar in Mediterranean and other climatic regions, the magnitude of responses tends to be intensified in Mediterranean systems. For example prolonged dry season flows may result in lower dissolved oxygen, higher temperatures and concentration of contaminants among other impacts (Cooper, Lake, Sabater, Melack, & Sabo, 2013). Climate change and increasing frequency and severity of drought promise to increase the conflict between human needs and ecological needs over time (Arthington, 2012).

Managing for Change: Modernizing California's Water Governance

Little Hoover Commission | August 1st, 2010

In this study, the Little Hoover Commission focused on how California organizes the functions of water supply, planning, management and accounting. From the start, the go

In this study, the Little Hoover Commission focused on how California organizes the functions of water supply, planning, management and accounting. From the start, the goal was to take a statewide view of California’s water resources activities and recommend a governance structure that could position California and Californians for the decades to come. The focus deliberately was on statewide governance, in part because of the already intense focus on the Sacramento-San Joaquin River Delta and also because of the Commission’s view that the Delta’s problems could not be resolved without a stronger, more accountable water governance structure for the state as a whole.

Managing Freshwater Discharge to the San Francisco Bay/Sacramento-San Joaquin Delta Estuary―The Scientific Basis for an Estuarine Standard

San Francisco Estuary Project | October 26th, 1992

Aquatic resources of the Sacramento-San Joaquin Delta and upper portions of San Francisco Bay have undergone significant declines over the past several decades. Species c

Aquatic resources of the Sacramento-San Joaquin Delta and upper portions of San Francisco Bay have undergone significant declines over the past several decades. Species characteristic of the Delta and rivers, such as striped bass and salmon, began to decline during the late 1970s. Prolonged drought, large diversions of fresh water, and dramatic increases in populations of introduced aquatic species during the 1980s and 1990s brought a number of indigenous aquatic species to extremely low levels. Species that spend more of their lives downstream of the Delta, including Delta smelt, longfin smelt, and many zooplankton, maintained large populations through the 1970s, but declined sharply after the mid-1980s. Declines in aquatic resources have led to curtailed fishing seasons, to petitions for endangered species status, and general concern about the health of the estuarine ecosystem.