Clear Lake Watershed

EPA Grant Number: R825433C011
Subproject: this is subproject number 011 , established and managed by the Center Director under grant R825433
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: EERC - Center for Ecological Health Research (Cal Davis)
Center Director: Rolston, Dennis E.
Title: Clear Lake Watershed
Investigators: Suchanek, Thomas , Rejmankova, Eliska , Cech, Joseph , Schladow, S. G. , Goldman, Charles R. , Anderson, Daniel , Layton, David , Wilen, James , Richerson, Peter
Institution: University of California - Davis
EPA Project Officer: Packard, Benjamin H
Project Period: October 1, 1996 through September 30, 2000
RFA: Exploratory Environmental Research Centers (1992) RFA Text |  Recipients Lists
Research Category: Center for Ecological Health Research , Targeted Research


The goal of the research is to test new analytical methods and hypotheses on how multiple stresses interact to affect target organisms and management endpoints of interest. We wish to demonstrate how technical information can be brought to managers to solve practical problems.


Clear Lake and its watershed constitute a complex ecosystem with multiple management objectives and several major stressors at work. The lake is a large shallow, eutrophic system heavily used for recreation and water supply. It is an important habitat for waterfowl and fish-eating birds and mammals. Human uses conflict among themselves and with biodiversity values. It is an excellent laboratory ecosystem for the testing of concepts and methods for the management of multiple stresses. Clear Lake contrasts sharply in trophic state and other parameters with Lake Tahoe, making comparative studies particularly interesting, especially since both lakes have good long-term records.

The investigations of the problem of mercury ecotoxicology in Clear Lake are among the most thorough ever conducted on one ecosystem. The investigators have the data and methods to understand the movement of Hg through this system from mine to grebe and osprey from mass-balance first principles. Progress has been made difficult questions such as rates of mercury methylation and demethylation, mechanisms of fish uptake of Hg, and the relative role of Clear Lake in generating exposures of migratory birds. Investigations of the role of habitat disturbance (stream channel damage, road building, wetland loss) in the eutrophication of the lake led to the hypothesis that the advent of powered earthmoving machinery in the 1920s caused a pervasive pattern of watershed disturbance. Recent core data, show a dramatic increase in mercury loading, sediment influx and many other changes in the last few decades, consistent with the hypothesis.

Expected Results:

Under Center auspices the Clear Lake watershed is developing into an excellent laboratory ecosystem. Although the aggregate support from non-Center sources considerably exceeds Center funding, none of the other contributing projects allows an integration of all projects to give a systemic view of the watershed and its problems. Center funds target essential projects for integration, such as the economic analysis of the relative importance of the different management problems. Center funds will also support pilot projects, such as our environmental history/coring project, which should eventually attract substantial external funding. The Center is also a forum for comparative discussions of watershed scale problems. The Clear Lake history/coring project is closely modeled on a similar project at Tahoe, partly because the investigators can take advantage of expertise developed by Tahoe workers, but also because the comparisons of the stresses affecting these two watersheds, contrasting sharply in some dimensions (trophic state), but similar in others (summer arid climate), will be illuminating.

Supplemental Keywords:

watershed, aquatic ecosystem restoration, Clear Lake, mercury, fate and transport, ecosytem modeling, ecotoxicology., RFA, Scientific Discipline, INTERNATIONAL COOPERATION, Water, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Water & Watershed, mercury transport, Restoration, Aquatic Ecosystem, Environmental Microbiology, Biochemistry, Environmental Monitoring, Terrestrial Ecosystems, Ecology and Ecosystems, Aquatic Ecosystem Restoration, Mercury, Watersheds, mercury uptake, anthropogenic stress, contaminant exposure, watershed management, biodiversity, Clear Lake watershed, agricultural watershed, Clear Lake, agricultural watersheds, fish-eating birds, marine biogeochemistry, restoration strategies, watershed influences, integrated watershed model, aquatic ecosystems, environmental stress, ecosystem stress, ecological impact, lake ecosystems, ecological research

Progress and Final Reports:

  • 1997
  • 1998
  • 1999
  • Final

  • Main Center Abstract and Reports:

    R825433    EERC - Center for Ecological Health Research (Cal Davis)

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R825433C001 Potential for Long-Term Degradation of Wetland Water Quality Due to Natural Discharge of Polluted Groundwater
    R825433C002 Sacramento River Watershed
    R825433C003 Endocrine Disruption in Fish and Birds
    R825433C004 Biomarkers of Exposure and Deleterious Effect: A Laboratory and Field Investigation
    R825433C005 Fish Developmental Toxicity/Recruitment
    R825433C006 Resolving Multiple Stressors by Biochemical Indicator Patterns and their Linkages to Adverse Effects on Benthic Invertebrate Patterns
    R825433C007 Environmental Chemistry of Bioavailability in Sediments and Water Column
    R825433C008 Reproduction of Birds and mammals in a terrestrial-aquatic interface
    R825433C009 Modeling Ecosystems Under Combined Stress
    R825433C010 Mercury Uptake by Fish
    R825433C011 Clear Lake Watershed
    R825433C012 The Role of Fishes as Transporters of Mercury
    R825433C013 Wetlands Restoration
    R825433C014 Wildlife Bioaccumulation and Effects
    R825433C015 Microbiology of Mercury Methylation in Sediments
    R825433C016 Hg and Fe Biogeochemistry
    R825433C017 Water Motions and Material Transport
    R825433C018 Economic Impacts of Multiple Stresses
    R825433C019 The History of Anthropogenic Effects
    R825433C020 Wetland Restoration
    R825433C021 Sierra Nevada Watershed Project
    R825433C022 Regional Transport of Air Pollutants and Exposure of Sierra Nevada Forests to Ozone
    R825433C023 Biomarkers of Ozone Damage to Sierra Nevada Vegetation
    R825433C024 Effects of Air Pollution on Water Quality: Emission of MTBE and Other Pollutants From Motorized Watercraft
    R825433C025 Regional Movement of Toxics
    R825433C026 Effect of Photochemical Reactions in Fog Drops and Aerosol Particles on the Fate of Atmospheric Chemicals in the Central Valley
    R825433C027 Source Load Modeling for Sediment in Mountainous Watersheds
    R825433C028 Stress of Increased Sediment Loading on Lake and Stream Function
    R825433C029 Watershed Response to Natural and Anthropogenic Stress: Lake Tahoe Nutrient Budget
    R825433C030 Mercury Distribution and Cycling in Sierra Nevada Waterbodies
    R825433C031 Pre-contact Forest Structure
    R825433C032 Identification and distribution of pest complexes in relation to late seral/old growth forest structure in the Lake Tahoe watershed
    R825433C033 Subalpine Marsh Plant Communities as Early Indicators of Ecosystem Stress
    R825433C034 Regional Hydrogeology and Contaminant Transport in a Sierra Nevada Ecosystem
    R825433C035 Border Rivers Watershed
    R825433C036 Toxicity Studies
    R825433C037 Watershed Assessment
    R825433C038 Microbiological Processes in Sediments
    R825433C039 Analytical and Biomarkers Core
    R825433C040 Organic Analysis
    R825433C041 Inorganic Analysis
    R825433C042 Immunoassay and Serum Markers
    R825433C043 Sensitive Biomarkers to Detect Biochemical Changes Indicating Multiple Stresses Including Chemically Induced Stresses
    R825433C044 Molecular, Cellular and Animal Biomarkers of Exposure and Effect
    R825433C045 Microbial Community Assays
    R825433C046 Cumulative and Integrative Biochemical Indicators
    R825433C047 Mercury and Iron Biogeochemistry
    R825433C048 Transport and Fate Core
    R825433C049 Role of Hydrogeologic Processes in Alpine Ecosystem Health
    R825433C050 Regional Hydrologic Modeling With Emphasis on Watershed-Scale Environmental Stresses
    R825433C051 Development of Pollutant Fate and Transport Models for Use in Terrestrial Ecosystem Exposure Assessment
    R825433C052 Pesticide Transport in Subsurface and Surface Water Systems
    R825433C053 Currents in Clear Lake
    R825433C054 Data Integration and Decision Support Core
    R825433C055 Spatial Patterns and Biodiversity
    R825433C056 Modeling Transport in Aquatic Systems
    R825433C057 Spatial and Temporal Trends in Water Quality
    R825433C058 Time Series Analysis and Modeling Ecological Risk
    R825433C059 WWW/Outreach
    R825433C060 Economic Effects of Multiple Stresses
    R825433C061 Effects of Nutrients on Algal Growth
    R825433C062 Nutrient Loading
    R825433C063 Subalpine Wetlands as Early Indicators of Ecosystem Stress
    R825433C064 Chlorinated Hydrocarbons
    R825433C065 Sierra Ozone Studies
    R825433C066 Assessment of Multiple Stresses on Soil Microbial Communities
    R825433C067 Terrestrial - Agriculture
    R825433C069 Molecular Epidemiology Core
    R825433C070 Serum Markers of Environmental Stress
    R825433C071 Development of Sensitive Biomarkers Based on Chemically Induced Changes in Expressions of Oncogenes
    R825433C072 Molecular Monitoring of Microbial Populations
    R825433C073 Aquatic - Rivers and Estuaries
    R825433C074 Border Rivers - Toxicity Studies