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Water: Total Maximum Daily Loads (303d)

Appendix C - Screening Categories


Guidance for Water Quality-Based Decisions:
The TMDL Process

This list of screening categories is based on categories promulgated as the minimum data set a State should consider when developing their list of impaired waters pursuant to section 304(l) of the Clean Water Act. When developing lists pursuant to this guidance and to meet the requirements of section 303(d), a State should, at a minimum, use these categories to identify their water quality-limited waters. States should also consider additional information, such as TRI data, streamflow information collected by USGS, locally available data, and public comments on proposed 303(d) lists.

  1. Waters where fishing or shellfish bans and/or advisories are currently in effect or are anticipated.
  2. Waters where there have been repeated fishkills or where abnormalities (cancers, lesions, tumors, etc.) have been observed in fish or other aquatic life during the last ten years.
  3. Waters where there are restrictions on water sports or recreational contact.
  4. Waters identified by the State in its most recent State section 305(b) report as either "partially achieving" or "not achieving" designated uses.
  5. Waters listed under sections 304(l) and 319 of the CWA.
  6. Waters identified by the State as priority waterbodies. (State Water Quality Management plans often include priority waterbody lists which are those waters that most need water pollution control decisions to achieve water quality standards or goals.)
  7. Waters where ambient data indicate potential or actual exceedances of water quality criteria due to toxic pollutants from an industry classified as a primary industry in Appendix A of 40 CFR Part 122.
  8. Waters for which effluent toxicity test results indicate possible or actual exceedances of State water quality standards, including narrative "free from" water quality criteria or EPA water quality criteria where State criteria are not available.
  9. Waters with primary industrial major dischargers where dilution analyses indicate exceedances of State narrative or numeric water quality criteria (or EPA water quality criteria where state standards are not available) for toxic pollutants, ammonia, or chlorine. These dilution analyses must be based on estimates of discharge levels derived from effluent guidelines development documents, NPDES permits or permit application data (e.g., Form 2C), Discharge Monitoring Reports (DMRs), or other available information.
  10. Waters with POTW dischargers requiring local pretreatment programs where dilution analyses indicate exceedances of State water quality criteria (or EPA water quality criteria where State water quality criteria are not available) for toxic pollutants, ammonia, or chlorine. These dilution analyses must be based upon data from NPDES permits or permit applications (e.g., Form 2C), Discharge Monitoring Reports (DMRs), or other available information.
  11. Waters with facilities not included in the previous two categories such as major POTWs, and industrial minor dischargers where dilution analyses indicate exceedances of numeric or narrative State water quality criteria (or EPA water quality criteria where State water quality criteria are not available) for toxic pollutants, ammonia, or chlorine. These dilution analyses must be based upon estimates of discharge levels derived from effluent guideline development documents, NPDES permits or permit application data, Discharge Monitoring Reports (DMRs), or other available information.
  12. Waters classified for uses that will not support the "fishable/swimmable" goals of the Clean Water Act.
  13. Waters where ambient toxicity or adverse water quality conditions have been reported by local, State, EPA, or other Federal agencies, the private sector, public interest groups, or universities. These organizations and groups should be actively solicited for research they may be conducting or reporting. For example, university researchers, the United States Department of Agriculture, the National Oceanic and Atmospheric Administration, the United States Geological Survey, and the United States Fish and Wildlife Service are good sources of field data and research.
  14. Waters identified by the State as impaired in its most recent Clean Lake Assessments conducted under section 314 of the Clean Water Act.
  15. Waters identified as impaired by nonpoint sources in America's Clean Water: The States' Nonpoint Source Assessments 1985 (Association of State and Interstate Water Pollution Control Administrators (ASIWPCA)) or waters identified as impaired or threatened in a nonpoint source assessment submitted by the State to EPA under section 319 of the Clean Water Act.
  16. Surface waters impaired by pollutants from hazardous waste sites on the National Priority List prepared under section 105(8)(A) of CERCLA.
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Table of Contents Chapter 1 Chapter 2 Chapter 3
Chapter 4 Appendix A Appendix B Appendix C
apd ape apf apg
acro sections


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