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 This website is no longer updated and links to external websites and some internal pages may not work.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 »

Related Links to CADDIS

On the CADDIS website, we refer to many other sites containing information useful in causal assessment. Several of these websites are presented below (note that this list is not comprehensive, but rather highlights some key resources).

Note: Although CADDIS can be used to identify the cause of any biological impairment, it was developed specifically to support the designation of Total Maximum Daily Loads (TMDLs) under the Clean Water Act.

U.S. EPA Links​

  • EPA's biocriteria program provides guidance and technical assistance for state and tribe water quality programs, including a Biological Assessment, Criteria and Indicators Discussion Database.
  • EPA's Center for Exposure Assessment Modeling (CEAM) provides predictive exposure assessment techniques for aquatic terrestrial and multimedia pathways for organic chemicals and metals. AQUATOX, one of the models available from CEAM, is a simulation model that examines how pollutants (e.g., nutrients, organic compounds) may affect aquatic ecosystems.
  • EPA's ECOTOX (ECOTOXicology) database provides single chemical toxicity information for aquatic and terrestrial life. ECOTOX is a useful tool for examining impacts of chemicals on the environment. Peer-reviewed literature is the primary source of information encoded in the database.
  • EPA's EnviroAtlas provides interactive resources that allow users to discover, analyze, and download data, maps, and other information. EnviroAtlas can be used to inform decision-making at multiple scales. EnviroAtlas resources are organized around the benefits people receive from nature or "ecosystem services".​
  • EPA's Healthy Watersheds Protection (HWP) web site provides information on the importance of healthy watersheds to our waters, how they can be assessed and protected, and what EPA is doing to support states and other partners in their protection of high quality waters. Assessment sections of this site describe the healthy watersheds assessment methodology and several statewide or river basin-wide watershed assessment reports.
  • EPA's How's My Waterway is an application that accesses EPA’s national database of State water quality monitoring reports provided under the Clean Water Act, reformatted to be fast and user-friendly at local scale. Learn the condition of local streams, lakes and other waters anywhere in the US... quickly and in plain English. See if your local waterway was assessed for pollution, what was found, and what is being done.
  • EPA's Health and Environmental Research Online (HERO) database provides an easy way to access and influence the scientific literature behind EPA science assessments. The database includes more than 600,000 scientific references and data from the peer-reviewed literature used by EPA to develop its regulations and science assessments.
  • EPA's Quality Program provides requirements for conducting quality management activities for all environmental data collection and environmental technology programs performed by or for the Agency. The primary goal of the program is to ensure that the Agency’s environmental decisions are supported by data of known and documented quality. The program also covers the implementation of the EPA Information Quality Guidelines.
  • EPA's Recovery Potential Screening (RPS) web site provides technical tools and step by step methods to help government and private programs compare watersheds and prioritize their efforts for greater likelihood of restoration and protection success. RPS users have included most state water quality programs plus a variety of local watershed groups, river basin managers (US and international), tribes and federal environmental agencies. Statewide tools containing over 200 Watershed Index Online indicators are available for download, as well as an extensive summary of watershed indicator types.
  • EPA's Water Quality Standards Database (WQSDB) is being developed to display water quality standards (WQS), including designated uses and criteria, for the nation's surface waters.
  • EPA's Watershed Academy includes moderately technical subjects adapted for less advanced audiences. For example, the "Getting In Step" module provides information on how to improve outreach and stakeholder involvement within your watershed. The online training modules and certificate program have been used as a framework for college courses and independent studies.
  • EPA's Watershed Index Online (WSIO) is a free, publicly available data library of watershed indicators and comparison tools. It was developed by EPA to assist resource managers, citizens, and other users with comparing and prioritizing watersheds. In this site users can find downloadable data tables of over 450 ecological, stressor, and social indicators compiled for roughly 83,000 small-scale (HUC12s, average 36 sq mi) watersheds across the conterminous United States.
  • The National Aquatic Resource Surveys (NARS) are collaborative programs between EPA, states, and tribes designed to assess the quality of the nation's coastal waters, lakes and reservoirs, rivers and streams, and wetlands using a statistical survey design. The NARS provide critical, groundbreaking, and nationally-consistent data on the nation's waters.

Top of Page

Other Federal Agency Links

  • The U.S. Geological Survey (USGS) StreamStats Program is a web-based geographic information system (GIS) that provides users with access to analytical tools useful for water-resources planning and management (e.g., streamflow characteristics and drainage basin characteristics).
  • The USGS Toxic Substances Hydrology Program, provides scientific information on environmental contamination (e.g., from excessive nutrients, organic chemicals, toxic metals, and other contaminants).
  • The USGS PeakFQ Program is a software program that provides estimates of instantaneous annual-maximum peak flows for different recurrence intervals.
  • Under the USGS NAWQA (National Water-Quality Assessment) Program, USGS scientists collect and interpret data about surface- and ground-water chemistry, hydrology, land use, stream habitat, and aquatic life in parts or all of nearly all 50 States using a nationally consistent study design and uniform methods of sampling analysis. The Effects of Urbanization on Stream Ecosystems study is one component of the NAWQA Program.

Top of Page

Other Links

  • The Integrated Taxonomic Information System (ITIS) is a source for authoritative taxonomic informatin on plants, animals, fungi, and microbes of North America and the world.
  • FishBase is a global information system which provides taxonomic, life history, ecological and economic information for freshwater and marine fish. It was developed at the WorldFish Center in collaboration with the Food and Agriculture Organization of the United Nations and many other partners. Development was supported by the European Commission.
  • SMARTe, or Sustainable Management Approaches and Revitalization Tools - electronic, is an open-source, web-based decision support system for developing and evaluating future reuse scenarios for potentially contaminated land. SMARTe contains resources and analysis tools for all aspects of the revitalization process, including community involvement.
  • R is a free software statistical software package that provides access to a broad array of analytical tools. In CADDIS, the CADStat application is based on a Java Graphical User Interface (GUI) to R, referred to as "JGR."
  • The Horizons Systems' NHDPlus dataset web site (supported by the U.S. EPA's Office of Water and USGS) provides an integrated suite of geospatial data sets that incorporate many features of the National Hydrography Dataset, the National Elevation Dataset, the National Land Cover Dataset, and the Watershed Boundary Dataset.
  • The Pesticide Action Network (PAN) Pesticide Database provides information on toxicity and regulatory information for insecticides, herbicides, and other pesticides.

Top of Page