The Anatomy of a Drought in the Upper San Francisco Estuary: Water Quality and Lower-Trophic Responses to Multi-Year Droughts Over a Long-Term Record (1975-2021)

University of California, Davis (UC Davis) | December 23rd, 2024

The California Stream Condition Index

California State Water Resources Control Board (SWRCB) | December 1st, 2015

The California Stream Conditon Index (CSCI) is a biological scoring tool that helps aquatc resource managers translate complex data about benthic macroinver

The California Stream Conditon Index (CSCI) is a biological scoring tool that helps aquatc resource managers translate complex data about benthic macroinvertebrates found living in a stream into an overall measure of stream health. The CSCI score indicates whether, and to what degree, the ecology of a stream is altered from a healthy state. Direct measures of ecosystem health like the CSCI are preferable to those based on chemical or physical measurements for many management questons. Living organisms integrate the efects of multple stressors, such as sedimentaton, nutrient enrichment and riparian disturbance, over both space and tme.

The California Stream Condition Index (CSCI): A New Statewide Biological Scoring Tool for Assessing the Health of Freshwater Streams

California State Water Resources Control Board (SWRCB) | September 1st, 2015

California’s dramatic environmental diversity supports a broad array of natural stream types throughout the state. Bioassessment of freshwater stream and rivers is esp

California’s dramatic environmental diversity supports a broad array of natural stream types throughout the state. Bioassessment of freshwater stream and rivers is especially challenging in such a region because the reference condition, or the benchmark of biological condition expected when human disturbance in the environment is absent or minimal, varies greatly among natural stream types. Previous indices used by monitoring programs were developed on a regional basis to help partition the state’s environmental diversity, but statewide assessments were confounded by different criteria used in different regions. The CSCI, which translates complex data about individual benthic macroinvertebrates (BMIs) found living in a stream into an overall measure of stream health, was developed specifically to address some of the shortcomings of earlier indices. First, the CSCI was developed with a much larger, more representative data set that makes it applicable statewide and that covers the broad range of environmental variability among natural stream types. Second, the CSCI sets biological benchmarks for a site based on its site-specific environmental setting. Finally, the CSC combines two separate types of indices, each of which provides unique information about the biological condition of a stream: a multi-metric index (MMI) that measures ecological structure and function, and an observed-to-expected (O/E) index that measures taxonomic completeness. Together they provide multiple lines of evidence about the condition of a stream, providing greater confidence in results than a single index.

The California Stream Condition Index (CSCI): A New Statewide Biological Scoring Tool for Assessing the Health of Freshwater Streams

California State Water Resources Control Board (SWRCB) | October 19th, 2015

California’s dramatic environmental diversity supports a broad array of natural stream types throughout the state. Bioassessment of freshwater stream and rivers is espe

California’s dramatic environmental diversity supports a broad array of natural stream types throughout the state. Bioassessment of freshwater stream and rivers is especially challenging in such a region because the reference condition, or the benchmark of biological condition expected when human disturbance in the environment is absent or minimal, varies greatly among natural stream types. Previous indices used by monitoring programs were developed on a regional basis to help partition the state’s environmental diversity, but statewide assessments were confounded by different criteria used in different regions. The CSCI, which translates complex data about individual benthic macroinvertebrates (BMIs) found living in a stream into an overall measure of stream health, was developed specifically to address some of the shortcomings of earlier indices. First, the CSCI was developed with a much larger, more representative data set that makes it applicable statewide and that covers the broad range of environmental variability among natural stream types. Second, the CSCI sets biological benchmarks for a site based on its site-specific environmental setting. Finally, the CSCI combines two separate types of indices, each of which provides unique information about the biological condition of a stream: a multi-metric index (MMI) that measures ecological structure and function, and an observed-to-expected (O/E) index that measures taxonomic completeness.  Together they provide multiple lines of evidence about the condition of a stream, providing greater confidence in results than a single index.

The Collapse of Pelagic Fishes in the Upper San Francisco Estuary: El Colapso de los Peces Pelagicos en La Cabecera Del Estuario San Francisco

American Fisheries Society (AFS) | January 9th, 2007

Although the pelagic fish community of the upper San Francisco Estuary historically has shown substantial variability, a recent collapse has captured the attention of res

Although the pelagic fish community of the upper San Francisco Estuary historically has shown substantial variability, a recent collapse has captured the attention of resource managers, scientists, legislators, and the general public. The ecological and management consequences of the decline are most serious for delta smelt (Hypomesus transpacificus), a threatened species whose narrow range overlaps with large water diversions that supply water to over 25 million people. The decline occurred despite recent moderate hydrology, which typically results in at least modest recruitment, and investments of hundreds of millions of dollars in habitat restoration and environmental water allocations to support native fishes. In response to the pelagic fish collapse, an ambitious multi-agency research team has been working since 2005 to evaluate the causes of the decline, which likely include a combination of factors: stock-recruitment effects, a decline in habitat quality, increased mortality rates, and reduced food availability due to invasive species.

The Cost of Regulating Active Landfills for Water Quality

California State Water Resources Control Board (SWRCB) | January 3rd, 2016

This report to the legislature was prepared pursuant to Chapter 718, Statutes of 2010 (SB 855, Committee on Budget and Fiscal Review), which requires the State Water Reso

This report to the legislature was prepared pursuant to Chapter 718, Statutes of 2010 (SB 855, Committee on Budget and Fiscal Review), which requires the State Water Resources Control Board (State Water Board) to submit to the budget committees in each house of the legislature a report on the costs of regulating water quality at active landfills. The State Water Board and Regional Water Quality Control Boards (Regional Boards, collectively, the Water Boards) analyzed the cost of resources required to implement State and Federal statutes, regulations, and policies at these facilities. This report provides an overview of the Water Boards’ Land Disposal Program, followed by a cost analysis. The Water Boards’ Land Disposal Program provides regulatory oversight to 439 active landfills and 235 other waste management facilities in the State. Active landfills are all landfills that still pose a threat to the environment, even if they have stopped accepting waste. Active landfills are classified as operating or non-operating, with non-operating landfills including proposed, closing, and closed landfills. There are an estimated 1600 legacy landfills that were not included in the cost analysis for this report. Legacy landfills are waste management units that were closed, abandoned, or inactive prior to the adoption of revised State Water Board regulations in November 1984. In response to the legislative requirements, the results of this analysis show the cost of regulating the 439 active landfills to be approximately $18.1 million. The Land Disposal Program also regulates other waste management facilities as an integral part of the program, and tracks these facilities along with active landfills. Based on this analysis, the cost of regulating the 235 other waste management facilities is approximately $7.6 million. In total, implementation of the Land Disposal Program would cost approximately $25.7 million (not including legacy landfills). In Fiscal Year 2011-2012, the total expenditures incurred by the Land Disposal Program were approximately $10.6 million. As this presents an approximately $15.2 million shortfall in funding, the program prioritizes work based on threat to water quality, complexity, and level of activity at the facility. Working within existing resource constraints, the Land Disposal Program is currently implementing a series of efficiency measures to improve program effectiveness. A discussion of these efforts concludes this report.

The Decline of Striped Bass in the Sacramento-San Joaquin Estuary, California

American Fisheries Society (AFS) | July 1st, 1985

The abundance of young striped bass Morone saxatilis in the Sacramento-San Joaquin Estuary has suffered an unsteady but persistent decline from population levels that wer

The abundance of young striped bass Morone saxatilis in the Sacramento-San Joaquin Estuary has suffered an unsteady but persistent decline from population levels that were high in the middle 1960s. The decline was particularly severe in 1977 and abundance of young striped bass has been low every subsequent year. The adult striped bass population also has fallen during the past 20 years, but the exact period over which the decline occurred and the rate of decline are not clear. The adult population is now about one-quarter of its former size and there is little sign of recovery. We believe the Sacramento-San Joaquin striped bass population and the fishery that it supports are in serious danger. The cause is most likely one or more of four factors. (1) The adult population is now so low that egg production may be inadequate. (2) The plankton food supply of young striped bass in the western Sacramento-San Joaquin Delta and Suisun Bay has been greatly reduced each spring. Diversion of water from the delta for agricultural purposes is a prime suspect for the decrease in food production. (3) Large numbers of young fish are lost by entrainment in water diversions. (4) The population is stressed by toxic substances such as petrochemicals and pesticides. Additional studies are underway to help determine the principal cause(s) of the striped bass decline.

The Delta Plan: Ensuring a reliable water supply for California, a healthy Delta ecosystem, and a place of enduring value

Delta Stewardship Council (Delta Council) | May 16th, 2013

The Sacramento-San Joaquin River Delta is the grand confluence of California’s waters, the place where the state’s largest rivers merge in a web of channels—and in

The Sacramento-San Joaquin River Delta is the grand confluence of California’s waters, the place where the state’s largest rivers merge in a web of channels—and in a maze of controversy. The Delta is a zone where the wants of a modern society come into collision with each other and with the stubborn limitations of a natural system. In 2009, seeking an end to decades of conflict over water, the Legislature established the Delta Stewardship Council with a mandate to resolve long-standing issues. The first step toward that resolution is the document you have before you, the Delta Plan.

The Development of Nutrient Criteria for Ecoregions within: California, Arizona, and Nevada

U.S. Environmental Protection Agency (EPA) | January 1st, 2002

Development of regional nutrient criteria is one component of a larger strategy to address water quality problems associated with nutrient over-enrichment and cul

Development of regional nutrient criteria is one component of a larger strategy to address water quality problems associated with nutrient over-enrichment and culturally-induced accelerated rates of eutrophication of waterbodies in the U.S. The U.S. Environmental Protection Agency (EPA) and Department of Agriculture have several active program initiatives to address the nutrient overenrichment problem. These programs address point and nonpoint sources of pollution, evaluate public health impacts from animal feeding operations, conduct research and monitoring to provide data and assessment techniques to better characterize the problem, and have offer nutrient management policies to provide practical support to agricultural operations to reduce the export of nutrients from their lands. The purpose of the regional nutrient criteria development process is to provide numeric targets for the various nutrient management programs that are regionally appropriate by reflecting geographic variations of waterbody response to nutrients. The current nutrient criteria development process for California and EPA Region IX (California, Nevada, Arizona, and Hawaii) started with the publication of the National Strategy for the Development of Regional Nutrient Criteria (EPA 1998) in June 1998.

The Ecological Significance of the Submarine Discharge of Groundwater

Commonwealth Scientific and Industrial Research Organisation (CSIRO Publishing) | December 15th, 1980

Discharge of groundwater into the sea is widespread. Overlooking it may lead to serious misinterpretations of ecological data in studies of coastal pollution, of benthic

Discharge of groundwater into the sea is widespread. Overlooking it may lead to serious misinterpretations of ecological data in studies of coastal pollution, of benthic zonation and productivity, and of the flux of dissolved substances within and between bottom sediments and overlying water. Data are presented indicating that in the Perth region of Western Australia, submarine groundwater discharge delivers several times as much nitrate to coastal waters as does river runoff.