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

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

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 Joaquin Delta of northern California (Delta). The purpose of this report is to synthesize the data available from a nutrient and water-quality HF (about every 15 minutes) monitoring network operated by the U.S. Geological Survey in the northern Delta. In this report, we describe the network and focus on the purpose of each station. We then present and discuss the available data, at various timescales—first at the monthly, seasonal, and inter-annual timescales, and second, for comparison, at the tidal and event timescales. As expected, we determined that there is substantial variability in nitrate-N concentrations at short timescales within hours, but also significant variability at longer timescales such as months or years. Resolving this variability is made possible by the HF data, with the largest variability caused by storms, tides, and diel biological processes. Given this large temporal variability, calculations of cumulative nutrient fluxes (for example, daily, monthly, or annual loads) is difficult without HF data. For example, in the Cache Slough, calculation of the annual load without the tidal variability resulted in a 30 percent underestimation of the true annual load value. We conclude that HF measurements are important for accurate determination of fluxes and loads in tidal environments, but, more importantly, provide important insights into processes and rates of nutrient cycling. This report, along with the other two reports of this series (Bergamaschi and others, 2017; Kraus, Bergamaschi, and others, 2017), was drafted in cooperation with the Delta Regional Monitoring Program to help scientists, managers, and planners understand how HF data improve our understanding of nutrient sources and sinks, drivers, and effects in the Delta.

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

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

Ambient water quality monitoring programs have traditionally relied on the use of targeted monitoring designs (in which sampling locations are assigned non-randomly) to assess the condition of aquatic resources. As probability-based surveys (in which site locations are assigned randomly) have become more widely adopted, there has been a growing desire to combine data from targeted sites with data from probability sites when making overall assessments of resource condition. We evaluated the potential for combining datasets and present an approach to combining data from the two types of surveys. We compiled biological, chemical and habitat data from 63 probability sites and 133 targeted monitoring sites in southern coastal California and compared the distribution of analyte values collected under the two designs. This analysis clearly demonstrates that both targeted and probabilistic sampling designs are necessary for effective non-point source water quality monitoring programs. Probability designs are the only survey type capable of giving an objective overview of the range of conditions present in the resource of interest. By contrast, targeted designs often are needed to fill in critical data gaps and answer site-specific questions. We conclude that the most effective way to ‘integrate’ probability and targeted surveys is to use probability surveys to produce an unbiased regional framework for interpreting targeted results and to supplement this framework as needed with sites targeted to fill data gaps.

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

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

Since 2011, qualitative studies examining adoption of conservation practices and programs (CPPs) have burgeoned. This article presents a systematic review of all U.S.-based qualitative investigations into CPP adoption since 1996. We found three themes are discussed primarily as motivating adoption: farmer characteristics, environmental awareness, and trust in information sources. Four themes are discussed primarily as barriers to adoption: farm management, negative perceptions of a conservation practice, perceptions that adoption is a risk, and land tenure. Four themes were discussed as both motivations and barriers: economic factors, social norms, perceptions of government programs, and farm characteristics. Overall, we found farmers’ economic and management needs and their perceived and actual limitations to conservation behavior influenced adoption. Implications of our findings for policymakers and practitioners include promoting systems-based conservation strategies and stressing the benefits of conservation practices.

Tahoe: State of the Lake Report 2025

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

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

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 continuously since 1968. This has created a unique document of change for one of the world’s most iconic and vulnerable lakes.

Talbert Seawater Intrusion Barrier Operations & Maintenance Manual

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

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

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 designs and improved injection water quality. Since 2008, the Talbert Barrier has been injecting advanced treated wastewater from OCWD’s GWRS treatment plant. This manual will examine in detail the various types of injection wells, their operational procedures and the procedures followed to monitor the quality of the injection water and evaluate injection well performance. Due to size, this document has been divided. Part 1, Part 2

Technical Approach to Develop Nutrient Numeric Endpoints for California

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

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.

Technical Approach To Develop Nutrient Numeric Endpoints For California Estuaries

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

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.

Technical Guidance on Implementing the Stormwater Runoff Requirements for Federal Projects under Section 438 of the Energy Independence and Security Act

U.S. Environmental Protection Agency (EPA) | December 1st, 2009

Stormwater runoff is a leading contributor to water pollution in urban and developing areas in the United States. Section 438 of the Energy Independence and Security Act

Stormwater runoff is a leading contributor to water pollution in urban and developing areas in the United States. Section 438 of the Energy Independence and Security Act of 2007 (EISA)  requires agencies to protect water resources by reducing stormwater runoff from any federal development projects. In December 2007, Congress enacted the Energy Independence and Security Act of 2007. Section 438 of that legislation establishes strict stormwater runoff requirements for federal development and redevelopment projects.  The provision reads as follows: “Storm water runoff requirements for federal development projects. The sponsor of any development or redevelopment project involving a Federal facility with a footprint that exceeds 5,000 square feet shall use site planning, design, construction, and maintenance strategies for the property to maintain or restore, to the maximum extent technically feasible, the predevelopment hydrology of the property with regard to the temperature, rate, volume, and duration of flow.” The intent of Section 438 of the Energy Independence and Security Act of 2007 (EISA) is to require federal agencies to develop and redevelop applicable facilities in a manner that maintains or restores stormwater runoff to the maximum extent technically feasible. Until recently, stormwater programs established to address water quality objectives have been designed to control traditional pollutants that are commonly associated with municipal and industrial discharges, e.g., nutrients, sediment, and metals. Increases in runoff volume and peak discharge rates have been regulated through state and local flood control programs. Although these programs have merit, knowledge accumulated during the past 20 years has led stormwater experts to the conclusion that conventional approaches to control runoff are not fully adequate to protect the nation’s water resources (National Research Council, 2008). Implementation of Section 438 of the EISA can be achieved through the use of the green infrastructure/low impact development (GI/LID) infrastructure tools described in this guidance. The intention of the statute is to maintain or restore the pre-development site hydrology during the development or redevelopment process. To be more specific, this requirement is intended to ensure that receiving waters are not negatively impacted by changes in runoff temperature, volumes, durations and rates resulting from federal projects. It should also be noted that a performance-based approach was selected in lieu of a prescriptive requirement in order to provide site designers maximum flexibility in selecting control practices appropriate for the site.

Technical Report for the Interagency Ecological Program (IEP) Pelagic Organism Decline (POD) Workgroup: Assessment of Aquatic Herbicide Use in the Delta

San Francisco Estuary Institute (SFEI) | May 15th, 2006

Since 2001, the California Department of Boating and Waterways (DBW) has conducted an extensive water quality monitoring program in conjunction with its aquatic herbicide

Since 2001, the California Department of Boating and Waterways (DBW) has conducted an extensive water quality monitoring program in conjunction with its aquatic herbicide applications. In this report, the risk quotient calculation method utilized by the Aquatic Pesticide Monitoring Program (a USEPA Tier 1 risk assessment) was used to determine if there are patterns of Level of Concern exceedances that indicate the possibility of adverse impacts on the Delta aquatic ecosystem due to DBW aquatic herbicide applications. Level of Concern exceedances are indicative only of the need for further investigation of an application scenario and do not, in and of themselves, indicate adverse impacts. This type of risk analysis cannot quantify the potential additive or synergistic effects of all pelagic organism stressors (one of which would be aquatic herbicides) within the Delta. This risk assessment indicates that, with the exception of diquat dibromide applications, DBW herbicide applications are unlikely to have the potential to cause Delta ecosystem water quality impacts. While there were a number of Level of Concern exceedances for diquat, DBW and all regulatory agencies involved were aware of this potential prior to application. NOAA Fisheries requested that, when possible, diquat used adjacent to salmon migratory routes should be reduced or avoided when that species is likely to be present. USFWS determined that diquat impact to aquatic invertebrates is minimal, temporary, and not likely to jeopardize Delta smelt but has required avoidance in areas where and when the smelt are known to be present. For 2006, NOAA has allowed DBW to treat sites in April and May with fluridone, which has allowed the use of diquat to be discontinued.

Technical Report on Barriers: A part of the comprehensive survey of San Francisco Bay and tributaries, California

U.S. Army Corps of Engineers (USACE) | March 15th, 1963