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  • Title

    Operation Baseline Project 2A1: USGS Pilot Studies

    Lead U.S. Geological Survey [USGS]
    Description Two pilot studies were funded to establish a baseline in open water and shallow wetland habitats prior to the WWTP upgrade. Study 1: Nutrient concentrations, transformation rates, and links to the foodweb. Study 2: Method to improve monitoring using fixed stations coupled with high-speed boat measurements
    Science topics Algae, Floating aquatic vegetation, Food webs, Nitrogen and ammonia, Open water, Other discharge contaminants, Phytoplankton, Submerged aquatic vegetation, Wastewater discharge, Water operations and exports, Wetlands, Zooplankton
    Updated December 14, 2022
  • Title

    Operation Baseline Project 2A2: USGS Pilot Studies - Isotopes

    Lead U.S. Geological Survey [USGS]
    Description Evaluate the usefulness of stable isotopes to trace nutrients form effluent water
    Science topics Algae, Floating aquatic vegetation, Food webs, Nitrogen and ammonia, Open water, Other discharge contaminants, Phytoplankton, Submerged aquatic vegetation, Wastewater discharge, Water operations and exports, Wetlands, Zooplankton
    Updated December 14, 2022
  • Title

    Quantifying Factors Affecting Migration Routing and Survival of Juvenile Late-Fall Chinook Salmon in the Sacramento-San Joaquin River Delta

    Lead U.S. Geological Survey [USGS]
    Description Juvenile Chinook salmon emigrating from natal tributaries of the Sacramento River must negotiate the Sacramento-San Joaquin River Delta where they disperse among the Delta's complex channel network. Natural processes and water management actions affect the fraction of the population using different migration routes through the Delta and survival within those routes, but quantifying these relationships has proven difficult. Since 2006, acoustic telemetry techniques have been used to quantify both movement among migration routes and survival within routes, providing the first insights into how route-specific survival contributes to population-level survival in the Delta. In this project, we propose to use existing acoustic telemetry data from multiple sources to 1) Quantify factors affecting migration routing of juvenile salmon emigrating from the Sacramento River, 2) Quantify factors affecting survival of juvenile salmon within specific migration routes, and 3) Simulate population-level survival through the Delta under a limited number of historical and operational scenarios. Collating telemetry data from multiple sources over numerous years offers a unique opportunity to identify important relationships that might otherwise be difficult to detect for any particular study in a given year. Quantifying such relationships is critical to informing resource management that seeks to balance use of water resources with recovery of endangered salmon populations.
    Science topics Chinook Salmon
    Updated April 29, 2022
  • Title

    CASCaDE II: Computational Asessments of Scenarios of Change for the Delta Ecosystem

    Lead U.S. Geological Survey [USGS]
    Description This proposal builds upon an existing model-based effort to develop a holistic view of the Bay-Delta-River-Watershed system. CASCaDE I developed a set of linked models to assess Delta ecosystem response to climate change. In CASCaDE II, we propose to refine and extend those modeling capabilities to assess Delta ecosystem response to changes in climate and physical configuration. With a new state-of-the-art hydrodynamic and sediment model at its core, CASCaDE II will link models of climate, hydrology, hydrodynamics, sediment, geomorphology, phytoplankton, bivalves, contaminants, marsh accretion, and fish. Our goals are to apply these linked models to 1) better understand Delta ecosystem function, 2) assess possible futures of the Delta under scenarios of climate and structural change, and 3) provide science-based information to support the DSC in its co-equal goals of water supply and ecosystem protection. The tools developed will provide an objective basis for anticipating and diagnosing Delta ecosystem responses to planned and unplanned changes. Experiments using the linked models are designed to address questions such as: How will climate change, together with new conveyance structures or increased flooded island habitat, alter water flow and drinking water quality? With projected changes in residence time, turbidity, temperature, and salinity, how will primary productivity, invasive bivalves, marsh processes, contaminant dynamics, and fish populations respond?
    Science topics None specified
    Updated April 29, 2022
  • Title

    Quantifying the contribution of tidal flow variations to survival of juvenile Chinook salmon

    Lead U.S. Geological Survey [USGS]
    Description The purpose of this project is to quantify how tides in the Delta influence survival of juvenile salmon. Juvenile salmon survival increases when there is more flow and the river is less tidally influenced. We hypothesize that the increase in survival is because of reduced travel times causing less exposure to predators. This project will test this hypothesis using multiple models including ones that can predict how management actions that modify tidal patterns affect juvenile salmon survival.
    Science topics Chinook Salmon, Salmon migration, Surface water flow, Tides, Water management
    Updated June 17, 2024
  • Title

    Assessing Sediment Nutrient Storage and Release in the Delta: Linking Benthic Nutrient Cycling to Restoration, Aquatic Vegetation, Phytoplankton Productivity, and Harmful Algal Blooms

    Lead U.S. Geological Survey [USGS]
    Description Nutrients in sediment play a large role in influencing food webs, harmful algal blooms, aquatic vegetation, and drinking water quality. This study will investigate the amount, types, and dynamics of nutrients in Delta sediments. It will also examine sediment microbial communities that mediate these processes. Results of this study will help determine how the planned reduction in nutrient inputs to the Delta will effect sediment nutrients and microbial communities following the upgrade of the Sacramento Regional County Sanitation District's wastewater treatment plant. Data will also inform how wetland restoration and invasive aquatic vegetation influence sediment nutrients and microbial communities. These data will contribute to improving computer models that inform large-scale nutrient management actions.
    Science topics Aquatic vegetation, Benthic, Cyanobacteria, Harmful algal blooms HAB, Nitrogen, Nitrogen and ammonia, Nutrients, Phytoplankton, Sediments
    Updated November 12, 2025
  • Title

    CASCaDE: Computational Asessments of Scenarios of Change for the Delta Ecosystem

    Lead U.S. Geological Survey [USGS]
    Description Agencies of the CALFED Bay-Delta Authority (CBDA) face tough decisions as they search for strategies to meet their programmatic goals of stabilizing water supplies in California, providing safe drinking water to a growing population, and sustaining diverse populations of native species and their supporting ecosystem functions. The challenge of finding balanced solutions to these goals is daunting because of the enormous complexity of the San Francisco Bay-Delta system and its tributary rivers and their watersheds. The challenge grows as we consider the additional layer of complexity imposed by the certainty that all the key forces that drive dynamics of this ecosystem (climate, hydrology, water management, land use, sea level) will change significantly in future decades. This proposal describes a model-based approach for developing a long view of the Bay-Delta-River-Watershed system. The long view will be developed through simulations with linked models to project changes under a range of plausible scenarios of global warming, hydrologic responses, land-use change, reconfigurations of within-Delta habitats, and sea level rise. Our goals are to develop and apply a model-based approach of ecological forecasting to project future states of the Delta ecosystem under prescribed scenarios of change, and to communicate the outcomes of those scenarios to resource managers facing the daunting challenge of meeting CBDP goals in a continually changing world.
    Science topics None specified
    Updated November 18, 2022
  • Title

    Predation Dynamics Across Reach-Specific Gradients in Juvenile Salmon Survival

    Lead U.S. Geological Survey [USGS]
    Description

    Description The overarching goal of this project is to determine if predation by piscivorous fishes is an important explanatory driver of survival of juvenile Chinook Salmon emigrating through the north Delta. To achieve this goal, we seek to determine if variation in reach-specific characteristics of predation dynamics covary with survival of acoustictagged juvenile Chinook Salmon collected during the study period. This will be accomplished by comparing reach-specific characteristics of the piscivore community and its observed and modeled consumption of juvenile Chinook Salmon across a range of environmental conditions. Need This is not a mandated study but it addresses an important research need. Objectives: How does the piscivore community (species composition, size structure, and abundance) vary across specific migratory pathways (river reaches) in the North Delta? To what extent do environmental conditions (e.g., water temperature, turbidity, and discharge) control the consumption of juvenile Chinook Salmon? Do characteristics of the predator community explain variation in survival of acoustic tagged salmon collected during the study period?
    Science topics Predation
    Updated November 12, 2025
  • Title

    North American Breeding Bird Survey [BBS]

    Lead U.S. Geological Survey [USGS]
    Description The North American Breeding Bird Survey (BBS) is the primary source for critical quantitative data to evaluate the status of continental bird species, keeping common birds common and helping fuel a $75 billion wildlife watching industry.
    Science topics Mudflats, Intertidal and transition zones, Above highwater refugia, Main channels, Sloughs, Backwater, Seasonally flooded, Open water, Managed ponds, Riparian wildlife, Forests, Non forested vegetation, Delta islands, Pacific flyway, Waterfowl, Shorebirds, Gulls, Saltwater and freshwater marshes, Habitat, Birds, Non resident and overwintering birds
    Updated April 29, 2022
  • Title

    Water Quality Data for California

    Lead U.S. Geological Survey [USGS]
    Description The USGS collects and analyzes chemical, physical, and biological properties of water, sediment and tissue samples from across the Nation. The Water Data for the Nation discrete sample data base is a compilation of over 4.4 million historical water quality analyses in the USGS district data bases through September 2005. The discrete sample data is a large and complex set of data that has been collected by a variety of projects ranging from national programs to studies in small watersheds.
    Science topics Water temperature, Dissolved oxygen, pH, Conductivity
    Updated April 29, 2022
  • Title

    San Francisco Bay Bathymetry

    Lead U.S. Geological Survey [USGS]
    Description USGS has conducted bathymetric analyses in San Francisco Bay, Suisun Bay, and the Delta intermittently since 1867 based on bathymetry data primarily collected by NOAA"s National Ocean Service (NOS) (formerly the United States Coast and Geodetic Survey (USCGS)). Since the days of hydraulic gold mining, sedimentation in San Francisco Bay has changed drastically. From the 1850's until at least the late 1800's, debris from hydraulic mining in the Sierra Nevada filled the Bay. As hydraulic mining practices ceased, the amount of sediment deposited decreased. In the latter half of the 20th century an increase in the implementation of flood control and water distribution projects in the Central Valley caused the Bay to be erosional due to the reduction of the frequency and duration of peak flow conditions, which in turn decreased sediment supply to the Bay. They have used this information to locate deposits of sediment-associated contaminants, restore wetland areas, and to provide the observable linkage between anthropogenic modifications of the landscape—such as evolving land use practices, flood control, and water diversions—and natural forces of climate-driven river flow, sea level change, tides, and wind. In 1999, USGS assessed how sedimentation in the Suisun Bay has changed between 1867 and 1990 (see info sources). They have also worked collaboratively with DWR, using their more recent bathymetry data to produce a high-resolution DEM of the Delta region (see info sources). It is not clear whether USGS will continue their bathymetry surveys. The latest survey is from 2005, and took place in the South of San Francisco Bay (outside the Delta study area).
    Science topics Flood, Land elevation, Bedload, Deposition, Erosion, Main channels, Sloughs, Backwater
    Updated April 29, 2022
  • Title

    Water Quality in the Nation's Stream and Rivers

    Lead U.S. Geological Survey [USGS]
    Description In 1991, Congress established the National Water-Quality Assessment (NAWQA) Project to address where, when, why, and how the Nation's water quality has changed, or is likely to change in the future, in response to human activities and natural factors. A prominent feature of NAWQA is the development of long-term consistent and comparable information on streams, rivers, ground water, and aquatic systems. The NAWQA Project is designed to answer these questions: 1. What is the current condition of our Nation's streams, rivers, and groundwater? 2. How are these conditions changing over time? 3. How do natural features and human activities affect these conditions, and where are those effects most pronounced? Under the National Water-Quality Assessment (NAWQA) project, there are several surface water and ecology studies, including the Regional Stream Quality Assessment (RQSA) (a baseline assessment of streams), and current conditions and long-term trends monitoring.
    Science topics Wastewater discharge, Nitrogen and ammonia, Phosphorous, Carbon, Chlorophyll A B, Harmful algal blooms HAB, Suspended sediment, Chemistry, Toxicity, Salinity, Water temperature, Dissolved oxygen, pH, Turbidity, Hg and methyl mercury, Polychlorinated biphenyl PCB, Hydrocarbons and polycyclic aromatic hydrocarbons PAH, Flame retardants, Endocrine disruptors, Lead, Cadmium, Copper, Zinc, Arsenic, Selenium, Constituent of emerging concern CEC, Insecticides, Rodenticides, Herbicides, Fungicides, Microplastics, Other discharge contaminants, Main channels, Sloughs, Backwater, Benthos, Insects, Mollusks, Crustaceans, Fish, Invertebrates
    Updated April 29, 2022
  • Title

    Groundwater Quality Trends Monitoring

    Lead U.S. Geological Survey [USGS]
    Description Scientists are characterizing groundwater quality in principal aquifers, the primary source of the Nation's groundwater used for drinking. Concentrations of inorganic constituents, such as arsenic and nitrate, and organic constituents, such as pesticides and volatile organic compounds, are compared to benchmarks established for the protection of human health. Users can access an online tool to see how concentrations of pesticides, nutrients, metals, and organic contaminants in groundwater are changing during decadal periods across the Nation, and see in real time how chemical properties of groundwater at some sites are fluctuating. Groundwater quality data were collected from 5,000 wells between 1988-2001 (first sampling event) by the U.S. Geological Survey's National Water-Quality Assessment Project. Samples are collected in groups of 20-30 wells with similar characteristics called networks. About 1,500 of these wells in 67 networks were sampled about 10 years later between 2002-2012 (second sampling event) to evaluate decadal changes in groundwater quality. Between 2012 and 2016 (third sampling event), a subset of these networks has been sampled again, allowing additional results to be displayed on the web page: Decadal changes in groundwater quality. This is the third iteration of data added to the website, so this data release is referred to herein as Version 3.0. With the additional data, it is possible to evaluate changes in water quality between the 2nd and 3rd sampling event for 19 additional networks (35 total), changes in water quality between the 1st and 3rd sampling event for 15 additional networks (27 total), and changes across all 3 sampling events for 13 additional networks (27 total). A total of 78 networks have been sampled at least twice. Samples were obtained from monitoring wells, domestic-supply wells, and some public-supply wells before any treatment on the system.
    Science topics Groundwater, Nitrogen and ammonia, Salinity, Arsenic, Other discharge contaminants
    Updated April 29, 2022
  • Title

    Groundwater Ambient Monitoring and Assessment Program [GAMA]

    Lead U.S. Geological Survey [USGS]
    Description The Groundwater Ambient Monitoring and Assessment (GAMA) Program is California's comprehensive groundwater quality monitoring program that was created by the State Water Resources Control Board (State Water Board) in 2000. It was later expanded by Assembly Bill 599 - the Groundwater Quality Monitoring Act of 2001. AB 599 required the State Water Board, in coordination with an Interagency Task Force (ITF) and Public Advisory Committee (PAC) to integrate existing monitoring programs and design new program elements as necessary, resulting in a publicly accepted plan to monitor and assess groundwater quality in basins that account for 95% of the state's groundwater use. The GAMA Program is based on interagency collaboration with the State and Regional Water Boards, Department of Water Resources, Department of Pesticide Regulations, U.S. Geological Survey, and Lawrence Livermore National Laboratory, and cooperation with local water agencies and well owners.
    Science topics Groundwater, Salinity, Hg and methyl mercury, Hydrocarbons and polycyclic aromatic hydrocarbons PAH, Flame retardants, Endocrine disruptors, Lead, Arsenic, Selenium, Constituent of emerging concern CEC, Nitrogen and ammonia, Other discharge contaminants, Conductivity, Habitat, Fecal coliform E coli
    Updated April 29, 2022
  • Title

    Continuous Monitoring of Water Quality & Suspended-Sediment Transport [Bay-Delta]

    Lead U.S. Geological Survey [USGS]
    Description Our group at the USGS continuously monitors suspended-sediment concentration (SSC), turbidity, dissolved oxygen, temperature, salinity, and water level at many sites throughout the San Francisco Bay (Bay) and the Sacramento-San Joaquin Rivers Delta (Delta). Our work began in 1988 to explore the spatial and temporal variability of water quality and sediment transport and to provide decision makers, resource managers, and the public with the most up-to-date knowledge. Topics we study include water quality, sediment transport, water clarity, erosion and deposition, sediment-associated contaminants and habitat quality, wetland restoration, and sea level rise.
    Science topics Water operations and exports, Water storage, Water conveyance and infrastructure, Surface water flow, Stage, Velocity, Suspended sediment, Bedload, Deposition, Erosion, Chemistry, Toxicity, Salinity, Water temperature, Dissolved oxygen, Turbidity, Other discharge contaminants, Intertidal and transition zones, Main channels, Sloughs, Open water, Riparian wildlife, Conductivity, Water use and demand, Water intakes and fish screens and passage
    Updated April 29, 2022
  • Title

    Water Quality of San Francisco Bay

    Lead U.S. Geological Survey [USGS]
    Description This website provides information about the following components of water quality: salinity, temperature, suspended particulate matter, dissolved oxygen, light penetration, and chlorophyll concentration. These parameters are measured using a submersible instrument package called a CTD. This program complements the Interagency Ecological Program (IEP) for the San Francisco Bay/Delta Ecosystem.
    Science topics Solar irradiance, Chlorophyll A B, Suspended sediment, Salinity, Water temperature, Dissolved oxygen, Other discharge contaminants, Main channels
    Updated April 29, 2022
  • Title

    National Water Use Science Project [NWUSP]

    Lead U.S. Geological Survey [USGS]
    Description The USGS National Water Use Science Project (NWUSP), a component of the Water Availability and Use Science Program (WAUSP), facilitates the 5-year compilation of water use estimates for the United States as part of the National Water Census (NWC). The NWC, implemented as part of the SECURE (Science and Engineering to Comprehensively Understand and Responsibly Enhance) Water Act (Subtitle F of Public Law 111-11, the Omnibus Public Land Management Act), provides data and tools designed to support water managers in the accurate assessment of water availability at regional and national scales (https://water.usgs.gov/ watercensus/). Water managers across the United States require more complete, timely, and accurate water-availability information to support policy and decision-making, specifically, data associated with water withdrawals and consumptive use. Recognizing the limitations of current water-use data, the SECURE Water Act authorized a program that supports activities related to data collection and methods research and development at the State level. The USGS Water-Use Data and Research program (WUDR) will provide financial assistance through cooperative agreements with State water resource agencies to improve the availability, quality, compatibility, and delivery of water-use data that is collected or estimated by States. The Act requires that these State water use and availability datasets be integrated with appropriate datasets that are developed and/or maintained by the USGS.
    Science topics Surface water flow, Groundwater, Water use and demand
    Updated April 29, 2022
  • Title

    Berkeley Seismology Lab Geophysical Networks

    Lead U.S. Geological Survey [USGS]
    Description Together with the USGS Menlo Park, the Berkeley Seismological Laboratory reports earthquake information within a few minutes of occurrence. The BSL operates several different networks and has expanded into a broader range of geophysical monitoring: BARD, BDSN, BBN, and HRSN. BARD is a network of 33 continuously operating Global Positioning System receivers in Northern California. The primary goal of the network is to monitor crustal deformation across the Pacific-North America plate boundary and in the San Francisco Bay Area for earthquake hazard reduction studies and rapid earthquake emergency response assessment. The Berkeley Digital Seismic Network (BDSN) is a regional network of very broadband and strong motion seismic stations spanning Northern California and linked to UC Berkeley through continuous telemetry. The network is designed to monitor regional seismic activity as well as to provide high quality data for research in regional and global broadband seismology. The network currently consists of 40 stations, including an ocean-bottom seismometer in Monterey Bay (MOBB). The BSL operate a number of stations in the Bay Area with seismic and other geophysical sensors in boreholes. They are tools for observing tiny earthquakes and other deformation signals that may hint of incipient seismic movements. The High-Resolution Seismic Network is an array of borehole instrumentation deployed in the Parkfield area, with the goal of monitoring microseismicity on the San Andreas fault.
    Science topics Land elevation, Subsidence, Seismicity, Forests, Non forested vegetation, Delta islands
    Updated April 29, 2022
  • Title

    Regional Monitoring Program for Water Quality in San Francisco Bay

    Lead U.S. Geological Survey [USGS]
    Description The Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) is SFEI's largest program. It provides the information that regulators and decision-makers need to manage the Bay effectively. The RMP is an innovative collaborative effort between SFEI, the Regional Water Quality Control Board, and the regulated discharger community.
    Science topics Stage, Solar irradiance, Nitrogen and ammonia, Phosphorous, Carbon, Chlorophyll A B, Suspended sediment, Salinity, Water temperature, Dissolved oxygen, Turbidity, Hg and methyl mercury, Copper, Selenium, Other discharge contaminants, Main channels, Conductivity, Habitat
    Updated April 29, 2022
  • Title

    National Strong Motion Project [NSMP]

    Lead U.S. Geological Survey [USGS]
    Description The USGS National Strong-Motion Project (formerly titled the National Strong Motion Program) has the primary Federal responsibility for acquiring strong motion records of significant earthquakes in the United States recorded by sensors placed in the ground and in man-made structures. Currently the NSMP operates and maintains strong-motion instruments at more than 660 ground, free-field and reference sites, and more than 3200 channels of data from about 180 structural arrays. When a significant earthquake occurs, the NSMP automatically retrieves strong motion recordings from its instrumentation as well as from more than 2000 other instruments operated throughout the US by federal, state, and local agencies, private companies, and academic institutions that participate in the Advanced National Seismic System (ANSS). The NSMP rapidly processes these recordings according to COSMOS standards and archives the products at the Center for Engineering Strong Motion Data.
    Science topics Land elevation, Subsidence, Sea level rise, Seismicity, Forests, Non forested vegetation, Delta islands, Pacific flyway
    Updated April 29, 2022
  • Title

    Streamflow Monitoring

    Lead U.S. Geological Survey [USGS]
    Description The USGS works in partnership with more than 1,400 Federal, regional, State, Tribal, and local agencies or organizations to maintain and manage a multipurpose network of streamgages that monitor streamflow and (or) water level. Approximately 8,200 of the more than 10,000 USGS streamgages in the network continuously monitor streamflow year-round and are collectively referred to as the National 'Streamflow' Network (NSN). Approximately 40% of the NSN is made up of Federal Priority Streamgages (FPS), which are considered critical for long-term tracking and modeling/forecasting to ensure that Federal water priorities and responsibilities can be met. Such priorities and responsibilities include forecasting hydrologic events (floods and droughts);managing interstate agreements, compacts, court decrees, and other legal obligations;and tracking streamflow in major river basins and across borders.
    Science topics Water operations and exports, Water storage, Water conveyance and infrastructure, Wastewater discharge, Surface water flow, Stage, Velocity, Direction, Flood, Main channels, Sloughs, Backwater, Stormwater runoff and drainage, Water use and demand
    Updated April 29, 2022
  • Title

    Continuous Flow and Water Quality Monitoring Network in the Sacramento-San Joaquin Delta

    Lead U.S. Geological Survey [USGS]
    Description This project envisions the continuation, expansion, and further integration of high frequency monitoring for flow, water quality (including chlorophyll and nutrients), sediment, as well as biological responses at key locations in the Delta and Suisun Bay. The physical properties monitored by the fixed-station network are the primary drivers of the habitat conditions and biological responses that management actions hope to achieve. Nutrient dynamics are explicitly measured at select stations to improve our understanding of how physical dynamics, water quality and landscape features shape the base of Delta food webs. These data will provide information about drivers linked to food quantity and quality as well as potential toxins production by harmful algae. Suspended-sediment monitoring provides an understanding of the inputs and internal exchanges between regions, locations of sources and sinks, and provides insight into the underlying cause of turbidity variability in the study area. Suspended-sediment measurements gage the availability of suspended sediment for existing marshes and for proposed large-scale marsh restoration efforts in the Delta. There are a total of 4 teams associated with this work: • Hydrodynamics Team – Fixed Station Network Operation and Maintenance (Flow, Velocity, Gage Height, Core WQ) • BioGeoChemistry Team -- Fixed Station Network Operation and Maintenance (Expanded WQ, Nutrients, Phytoplankton) • Delta Sediment Team – Fixed Station Network Operation and Maintenance (Suspended Sediment, Delta) • Bay Team – Fixed Station Network Operation and Maintenance (Suspended Sediment and WQ in SF Bay)
    Science topics Chlorophyll A B, Conductivity, Dissolved oxygen, Flows, Nutrients, pH, Phytoplankton, Sediments, Stage, Surface water flow, Tides, Turbidity, Velocity, Water operations and exports, Water temperature
    Updated May 22, 2025
  • Title

    High-Frequency Monitoring of Delta Island Drainage Waters to inform carbon budgets and contaminant export

    Lead University of California - Santa Cruz [UCSC]
    Description This Proposition 1 funded study aims to use high-frequency measurements and paired grab samples to document water quality and carbon exports in relation to land use change on Delta Islands. The project involves monitoring one station on Twitchell Island and two on Staten Island.
    Science topics Landscape change
    Updated August 25, 2024
  • Title

    Harmful Algal Blooms and Cyanotoxins in the Delta: Occurrence, Distribution, Trends, and Environmental Drivers

    Lead U.S. Geological Survey [USGS]
    Description

    Cyanobacteria are the most common plankton causing harmful algal blooms in freshwater. The variety of cyanotoxins produced by cyanobacteria can impact the nervous system, liver, gastrointestinal tract, respiratory system, and skin of humans and other animals. In the Sacramento-San Joaquin Delta (Delta), cyanobacterial harmful algal blooms (cyanoHABs) have become more prevalent since the late 1990s. Even with the welldocumented occurrence of cyanoHABs in the Delta over the last 15 years, there is no consistent monitoring program in the region, making it challenging to identify management actions to mitigate their occurrence and effects.  

    To fill this knowledge gap, this project focused on measuring cyanotoxins and cyanoHABs in the Delta, organizing relevant data for stakeholders, and synthesizing data about cyanoHAB extent and drivers. In addition to the generation of new data, this project developed tools to integrate existing and future data collection efforts. Synthesis of these data will help assess the status and trends of cyanoHABs in the Delta, elucidate factors contributing to bloom formation, cyanotoxin production, and transport, and ultimately better understand the effects of cyanoHABs on humans, other animals, and the ecosystem.  
    Science topics Cyanobacteria, Harmful algal blooms HAB, Toxicity
    Updated March 10, 2026
  • Title

    Estimating Juvenile Production and Run Timing of Spring Chinook Salmon Leaving the Delta

    Lead U.S. Geological Survey [USGS]
    Description

    Spring-run Chinook salmon (Oncorhynchus tshawytscha) are a high-priority species under the Endangered Species Act due to their risk of extinction. However, understanding the factors affecting their populations is difficult when monitoring focuses only on returning adult spawners. This limited view overlooks critical life stages. To address this gap, the project aimed to estimate the number of juvenile salmon leaving the Delta at Chipps Island. Monitoring salmon throughout their entire life cycle is essential for identifying the key factors influencing their survival and reproduction.

    There is a need from both scientists and managers for accurate data to make informed decisions about salmon protection and conservation. The Department of Water Resources (DWR) mandates that juvenile production estimates for spring-run salmon be included in their incidental take permit, which is necessary for the continued operation of the State Water Project. A method to estimate juvenile abundance of spring-run salmon leaving the Delta (at Chipps Island) did not yet exist.

    To develop these annual estimates, researchers built on previous studies and incorporated new genetic data into updated models. This approach maximized the use of available information and the latest genetic research to improve the protection and understanding of these threatened fish.
    Science topics Chinook Salmon, Fish, Monitoring methods and techniques, Salmon migration
    Updated April 15, 2026