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Synergies between climate anomalies and hydrological modifications facilitate estuarine biotic invasions

Ecology Letters (Wiley) | June 6th, 2011

Summary

Environmental perturbation, climate change and international commerce are important drivers for biological invasions. Climate anomalies can further increase levels of hab

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Synthesis of data and studies relating to Delta Smelt biology in the San Francisco Estuary, emphasizing water year 2017

Interagency Ecological Program (IEP) | November 1st, 2021

Summary

In the San Francisco Estuary (SFE), the effects of freshwater flow on the aquatic ecosystem have been studied extensively over the years and remains a contentious managem

In the San Francisco Estuary (SFE), the effects of freshwater flow on the aquatic ecosystem have been studied extensively over the years and remains a contentious management issue. It is especially contentious with regards to the Delta Smelt (Hypomesus transpacificus), a species endemic to the SFE that has been listed as threatened under the Federal Endangered Species Act and endangered by the State of California. Early studies of Delta Smelt distribution within the SFE suggested that Delta Smelt habitat is determined largely by freshwater flow; however, the exact mechanisms and processes producing such benefits remained unclear. In the summer of 2017, the Flow Alteration Management, Analysis, and Synthesis Team (FLOAT-MAST) was established to analyze, synthesize, and summarize the data collected from the various flow-related monitoring and special studies occurring in 2017(see Table Intro 4). This report will focus on the 2017 summer-fall status of Delta Smelt and its habitat following a record wet year. There has been a long-term decline in the abundance of Delta Smelt associated with a decline in other pelagic fishes. Investigators concluded that the decline has likely been caused by the interactive effects of several causes, including changes in both physical and biotic habitats, many of which are tied to amount and timing of freshwater flow. For this report, we formulated a number of basic predictions about the likely effects of high flows in 2017 on Delta Smelt and their habitat (Table 3). We use a qualitative weight of evidence approach to evaluate whether these predictions were supported by available data. Data sources included a variety of long-term monitoring surveys conducted by Interagency Ecological Program (IEP) agencies, as well as model outputs. Delta Smelt population, health, and life history metrics rarely responded as predicted. Water temperature appears to have a stronger effect on Delta Smelt growth rate and some metrics of life history diversity than outflow or X2 position. Other life history diversity attributes varied but did not appear to be driven by outflow or temperature. Health status was difficult to interpret. Low prevalence of lesions and improved nutritional condition during the drought was contradicted by declining overall population levels. Because of the sparse catches of Delta Smelt in the post-POD years, we consider the data insufficient to reach firm conclusions about the predictions concerning range and distribution of Delta Smelt, especially in the fall. The prediction of high survival was not supported. The 2017 Delta Smelt year class began with poor recruitment in spring of 2017 and below average survival for spring to summer and summer to fall. Thus, low production and low survival led to low abundance of all life stages. During the fall to winter period survival improved, yet the resulting adults were low in number. Foraging success of the fish captured, as measured by stomach fullness, was high for juveniles and adults in 2017 relative to recent years associated with the higher densities of common zooplankton prey that occurred in 2017.

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Synthesis of Data from High-Frequency Nutrient and Associated Biogeochemical Monitoring for the Sacramento– San Joaquin Delta, Northern California

U.S. Geological Survey (USGS) | July 11th, 2017

Summary

This report is the second in a series of three reports that provide information about high-frequency (HF) nutrient and biogeochemical monitoring in the Sacramento–San J

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Synthesis of Studies in the Fall Low-Salinity Zone of the San Francisco Estuary, September–December 2011

U.S. Geological Survey (USGS) | July 14th, 2014

Summary

In fall 2011, a large-scale investigation (fall low-salinity habitat investigation) was implemented by the Bureau of Reclamation in cooperation with the Interagency Ecolo

In fall 2011, a large-scale investigation (fall low-salinity habitat investigation) was implemented by the Bureau of Reclamation in cooperation with the Interagency Ecological Program to explore hypotheses about the ecological role of low-salinity habitat in the San Francisco Estuary—specifically, hypotheses about the importance of fall low-salinity habitat to the biology of delta smelt Hypomesus transpacificus, a species endemic to the San Francisco Estuary and listed as threatened or endangered under federal and state endangered species legislation. The Interagency Ecological Program is a consortium of 10 agencies that work together to develop a better understanding of the ecology of the Estuary and the effects of the State Water Project and Federal Central Valley Project operations on the physical, chemical, and biological conditions of the San Francisco Estuary. The fall low-salinity habitat investigation constitutes one of the actions stipulated in the Reasonable and Prudent Alternative issued with the 2008 Biological Opinion of the U.S. Fish and Wildlife Service, which called for adaptive management of fall Sacramento-San Joaquin Delta outflow following “wet” and “above normal” water years to alleviate jeopardy to delta smelt and adverse modification of delta smelt critical habitat. The basic hypothesis of the adaptive management of fall low-salinity habitat is that greater outflows move the low-salinity zone (salinity 1–6), an important component of delta smelt habitat, westward and that moving the low-salinity zone westward of its position in the fall of recent years will benefit delta smelt, although the specific mechanisms providing such benefit are uncertain. An adaptive management plan was prepared to guide implementation of the adaptive management of fall low-salinity habitat and to reduce uncertainty. This report has three major objectives: •To provide a summary of the results from the first year of coordinated fall low-salinity habitat studies and monitoring. •To provide a synthesis of the results of the fall low-salinity habitat studies and other ongoing research and monitoring, to determine if the available information supports the hypotheses behind the adaptive management of fall low-salinity habitat as set forth in the adaptive management plan. •To begin to put the results from the fall low-salinity habitat studies into context within the larger body of knowledge regarding the San Francisco Estuary and, in particular, the upper San Francisco Estuary, including the Sacramento-San Joaquin Delta, Suisun Bay, and associated embayments.

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Synthesis Report: Integrating probability and targeted survey designs in regional stream condition assessments with examples from southern coastal California

California State Water Resources Control Board (SWRCB) | June 30th, 2010

Summary

Ambient water quality monitoring programs have traditionally relied on the use of targeted monitoring designs (in which sampling locations are assigned non-randomly) to a

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Synthesizing Conservation Motivations and Barriers: What Have We Learned from Qualitative Studies of Farmers’ Behaviors in the United States?

Society and Natural Resources (Routledge) | August 15th, 2019

Summary

Since 2011, qualitative studies examining adoption of conservation practices and programs (CPPs) have burgeoned. This article presents a systematic review of al

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Tahoe: State of the Lake Report 2025

University of California, Davis (UC Davis) | July 18th, 2025

Summary

UC Davis has conducted research at Lake Tahoe since 1950, and scientists from UC Davis Tahoe Environmental Research Center have been monitoring conditions at the lake con

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Talbert Seawater Intrusion Barrier Operations & Maintenance Manual

Orange County Water District (OCWD) | March 15th, 2023

Summary

OCWD’s Talbert Seawater Barrier (Talbert Barrier, Barrier) has been in operation since 1976. Since 1976 the Barrier has undergone many changes including new well design

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Technical Approach to Develop Nutrient Numeric Endpoints for California

California State Water Resources Control Board (SWRCB) | July 31st, 2006

Summary

This report provides an approach for the development of nutrient (nitrogen and phosphorus) numeric endpoints for use in the water quality programs of the California’s S

This report provides an approach for the development of nutrient (nitrogen and phosphorus) numeric endpoints for use in the water quality programs of the California’s State Water Resources Control Board (State Water Board) and Regional Water Quality Control Boards (Regional Water Boards). The approach provides a methodology to support several water quality program components including: setting numeric limits for National Pollutant Discharge Elimination System (NPDES) permits; development of Total Maximum Daily Load (TMDL) nutrient numeric endpoints; and for those Regional Water Boards that choose to, the development of numeric nutrient criteria. Guidance for this technical report comes from participants at workshop (Nutrient Numeric Endpoints Training Workshop held on May 18 & 19 2005 in Sacramento, CA) that is a part of a longer running process that has been sponsored by EPA Region IX and the State Water Board. The workshop summary (Summary of May 18-19, 2005 Nutrient Workshop) of this workshop can be downloaded from the project website: http://rd.tetratech.com/epa/. The CA Nutrient Numeric Endpoints process includes a Regional Technical Advisory Group (RTAG); and a collaborative forum of Regional Water Boards, Tribes, and other state and federal agencies in the State Regional Technical Advisory Group (STRTAG). The result of the RTAG / STRTAG process is an approach that has achieved a high level of consensus among participants. The purpose of this document is to describe the approach that has been reviewed and approved by the STRTAG. The intention of the proposed approach is to select nutrient response indicators that can be used to evaluate risk of use impairment, rather than using pre-defined nutrient limits that may or may not result in eutrophication for a particular water body. The report provides a description of the proposed approach that includes innovative elements such as: A water body classification framework that uses three Beneficial Use risk classification categories; Risk-based secondary indicators that are more closely linked to Beneficial Use condition than water column nutrient concentrations; and Modeling tools that provide the necessary linkage analysis between secondary indicators and water column nutrient concentrations. The modeling tools also account for site-specific cofactors such as flow, light availability, and others. This report provides the starting point for a process that will lead to refinements in the classification framework, secondary indicators, and linkage analysis modeling tools through the development of site-specific endpoints. The report has been reviewed by workshop participants; other State, Federal, and Tribal staff; and the Technical Evaluation Committee identified in Appendix 1. This report includes changes made in response to comments received. As an adaptive management process technical updates will be made and new dated editions of this document will be made available. A potential outcome of this process is the adoption of the framework and endpoints by various Regional Water Quality Control Boards for use as nutrient numeric criteria.

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Technical Approach To Develop Nutrient Numeric Endpoints For California Estuaries

California State Water Resources Control Board (SWRCB) | November 20th, 2007

Summary

Eutrophication is one of the top three leading causes of impairments of the nation’s waters, with demonstrated links between anthropogenic changes in watersheds, increa

Eutrophication is one of the top three leading causes of impairments of the nation’s waters, with demonstrated links between anthropogenic changes in watersheds, increased nutrient loading to coastal waters, harmful algal blooms, hypoxia, and impacts on aquatic food webs. These ecological impacts of eutrophication of coastal areas can have far-reaching consequences, including lowered fishery production, loss or degradation of seagrass and kelp beds, smothering of benthic organisms, nuisance odors, and impacts on human and marine mammal health. These modifications have significant economic and social costs. In California, the impacts of nutrient loading on estuaries and coastal waters have not been wel lmonitored. Without management actions to reduce anthropogenic nutrient loads, symptoms are expected to develop or worsen in the majority of systems, due to projected population increases in coastal areas. The purpose for this report is to outline a conceptual framework for the development of nutrient numeric endpoints (NNE) for estuaries and to highlight data gaps and research recommendations critical for their development. The purpose of NNEs for California estuaries is to provide a scientifically defensible framework that can serve as guidance for adopting regulatory numeric criteria. This framework is founded on an evaluation of risk relative to designated beneficial uses. The objective is to control excess nutrient loads to levels such that the risk of impairing the designated uses is minimized. If the nutrients present–regardless of actual magnitude–have a low probability of impairing uses, then water quality standards can be considered to be met. The ultimate goal of this effort is to develop a set of tools that can be used to support the water quality programs of the California State Water Resources Control Board (SWRCB), Regional Water Quality Control Boards and the regulated community. To reach this goal, we envision the development of a set of estuarine NNE tools, including 1) a classification scheme that groups estuaries according to factors that control their biological response to nutrient loading, 2) risk-based indicators of biological response that can provide quantitative measures of the status of beneficial uses relative to nutrient loads; 3) thresholds that define beneficial use risk categories (BURCs), which provides a framework for regulatory decisions based on quantitative assessments of impairment; and 4) modeling tools that link biological response indicators to watershed nutrient loads. To develop a NNE toolkit for estuaries, the first step in this process was to provide a working framework and to identify key data gaps and research recommendations critical for NNE development. The NNE conceptual framework for estuaries is based on previous work by the SWRCB and US EPA Region IX, which provided guidance for development of NNE in streams and lakes (TetraTech 2005). This framework is founded on the concept that biological response indicators are better suited to evaluate the risk of beneficial use impairment, rather than using pre-defined nutrient limits that may or may not result in mitigation of eutrophication for a particular water body. The advantage of the proposed approach is a more robust link to actual impairment of use, rather than an approach that relies on concentration data alone. The California NNE framework for estuaries is based on three organizing principals: • Biological response indicators provide a more direct risk-based linkage to beneficial uses than nutrient concentrations alone. • A weight of evidence approach with multiple indicators will produce NNE with greater scientific validity. • For many of the biological indicators associated with nutrients, no clear scientific consensus exists on a target threshold that results in impairment.

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Page : 108

Synergies between climate anomalies and hydrological modifications facilitate estuarine biotic invasions

Synthesis of data and studies relating to Delta Smelt biology in the San Francisco Estuary, emphasizing water year 2017

Synthesis of Data from High-Frequency Nutrient and Associated Biogeochemical Monitoring for the Sacramento– San Joaquin Delta, Northern California

Synthesis of Studies in the Fall Low-Salinity Zone of the San Francisco Estuary, September–December 2011

Synthesis Report: Integrating probability and targeted survey designs in regional stream condition assessments with examples from southern coastal California

Synthesizing Conservation Motivations and Barriers: What Have We Learned from Qualitative Studies of Farmers’ Behaviors in the United States?

Tahoe: State of the Lake Report 2025

Talbert Seawater Intrusion Barrier Operations & Maintenance Manual

Technical Approach to Develop Nutrient Numeric Endpoints for California

Technical Approach To Develop Nutrient Numeric Endpoints For California Estuaries

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