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Health and Environmental Effects Research

Aquatic Stressors

Part of EPA's mission is to protect and restore the physical, chemical, and biological integrity of our Nation's lakes, rivers, streams, and estuaries. Experts in the fields of the aquatic sciences agree that the most serious threats to our Nation's waters are the following four types of stressors:

In order to prevent the loss of biodiversity, EPA has an aggressive program underway to address stressor impacts to freshwater and marine systems and to develop the Diagnostics needed to determine the degree and cause of impairment in these systems.

EPA uses a unified approach to study the impact of major stressors and to develop diagnostic capabilities to protect aquatic systems. First, the current condition is assessed in order to determine the degree of impairment and second, a diagnosis of the cause(s) of impairment is made. This information can then be used to forecast the effects of changes of stressor levels that occur in the future. Subsequently, remediation and maintenance strategies are developed and implemented as part of EPA's overall water quality program. The final step is for EPA and States to use this information to develop standards.

For a highly detailed description of EPA's aquatic stressors research plan, download the document Aquatic Stressors: Framework and Implementation Plan for Effects Research (PDF, 197 pp, 3.21 MB, About PDF).

Research Highlights

Water montioring equipment

Water monitoring equipment at the Washington aqueduct.

  • A prototype modeling approach has been developed for examining watershed management effects related to habitat condition for Pacific salmon populations.
  • A general modeling framework has been assembled to forecast the effects of nutrient loads in the Gulf of Mexico. The model consists of a suite of linked and coupled models and synthesizes multimedia inputs, environmental data, and ecosystem dynamics. The following types of models are included: atmospheric, meteorological, hydrodynamic, sediment resuspension and transport, water quality, and eutrophication models.
  • As part of the project to establish nutrient loads, network models for determining food web indicators have been developed and applied to multiple estuaries of the Gulf of Mexico and Pacific Northwest.
  • An index of relative bed stability that describes current sediment conditions relative to expected conditions has been proposed and is currently being refined and tested. This new index is based upon an understanding of the relationship between sediment supply and transport.
  • An approach using probability-based sampling has been provided for developing geographic-specific water-quality criteria for pollution metrics. Currently, this approach is being used to support the development of criteria for suspended and bedded sediments.
  • Interspecies-correlation-estimation and acute-to-chronic estimation models have been developed to provide guidance for assessing the risks of chemicals to aquatic life, including endangered species, when data are limited.
  • A watershed classification framework for coastal systems has been developed for use in discriminating among watersheds with differing sensitivities to land-use and non-point stressors. This classification framework has been successfully tested in case studies within Great Lake states. An evaluation of a comprehensive watershed classification framework for the state of West Virginia is also underway.

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