An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Ecological Exposure Research: Water

Bird drinking water

The Nation’s water bodies are a crucial component of its ecosystems. EPA’s ecological exposure research on water is spread over several areas: detection, assessment, function, and outcomes. Detection has to do with our ability to determine whether a water body has been exposed to a stressor, such as a harmful chemical. Assessment projects deal with developing ways to more efficiently evaluate the health of water bodies. Function research looks at what water bodies do for us, such as providing drinking water or habitat for fish, and how to protect those functions. Water research in outcomes is designed to help understand the relationships between exposure of a water body to chemicals and the populations of fish in those water bodies. Together, these water research projects help protect the nation's wetlands, streams, rivers, and lakes.

Detecting and Monitoring Aquatic Invasive Species
EPA ecological exposure scientists are developing new DNA-based tools for the early detection and monitoring of aquatic invasive species. These tools will help prevent future invasions and the spread of existing exotic species. The spread of invasive species in our nation’s waters has costly economic and ecological impacts. The exchange of ballast water from the hulls of ships is one of the ways that these invasive species are introduced.

Classification of Functional Process Zones in Large Rivers
EPA's ecological exposure scientists are developing tools to rapidly classify river segments based upon their hydrology and geology to help identify areas of river systems that are best candidates for cleanup efforts. Each river is unique, and comparing areas of two different rivers often will not provide useful information. By classifying river segments into "Functional Process Zones" that categorize stream sections by how they work in the overall system, EPA's scientists are helping states and local governments identify the best areas to devote river cleanup funds and efforts.

Molecular Indicators (Exposure Biomarkers in Aquatic Organisms)
EPA scientists have found that plant and animal cells can change in very specific ways when they are exposed to chemicals and other pollutants To measure these changes, EPA researchers have developed biomarker-based methods that allow them to screen for molecular-level changes in aquatic organisms. These methods provide information about the concentrations of chemicals in aquatic ecosystems and the impact that chemicals may have on organisms that live there.

Headwater Streams
Ecological exposure researchers with EPA are developing ways to identify, assess, and maintain headwater streams where stream networks begin. The health of headwater streams is important to the quality of water downstream. EPA ecological exposure scientists have developed tools for assessing the quality and permanence of headwater streams to provide guidance for regional, tribal and state agencies in protecting these precious resources.

Development of DNA barcoding
EPA ecologists are using the unique DNA "barcodes" of certain aquatic species to develop faster, cheaper methods for assessing the health of streams and lakes. Traditionally, researchers have had to collect specimens of aquatic species and analyze them in a laboratory—a process that can be time-consuming, expensive, and labor-intensive. By finding short, identifying DNA sequences, also referred to as barcodes, EPA’s scientists are able to quickly and inexpensively identify the kinds of organisms present in lakes and rivers, making it easier to assess the overall health of these ecosystems.

Other Projects:

Wetlands - Understanding the Provisioning of Ecosystem Services
EPA is conducting research that will help scientists identify and understand the services provided by wetlands. These complex ecosystems not only are homes for countless animal and plant species, they also help keep rivers and streams free of contamination by trapping agricultural runoff from nearby fields. This information will help EPA scientists develop new, sustainable ways to maintain the water quality of our rivers.

Innovative Physical, Chemical and Biological Tools to Assess Sediment Remediation Performance
EPA scientists are studying rivers where new techniques are being used to help decrease sedimentation. When a river or stream has too much sediment, water quality downstream can suffer. EPA's ecologists are evaluating sedimentation reduction techniques to learn how effective they are, and what impact, if any, they have on the physical, chemical, and biological health of rivers.