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Water: Total Maximum Daily Loads (303d)

Overview of TMDL Program Results Analysis

For much of the TMDL Program's history, it has been difficult to analyze the program's environmental results because the entire sequence of TMDL development, TMDL implementation and impaired waters recovery often takes several years. As of January 2011, over 45,000 TMDLs have been developed. More TMDLs are now maturing and producing results that provide an opportunity to assess how well the TMDL Program is working. Results analysis involves assessing measures of environmental outcomes, their probable causes, and program progress in order to generate the insights needed to improve impaired waters programs. The TMDL Program Results Analysis Project was undertaken to improve our understanding of TMDL-specific program results patterns, explain these patterns, and develop appropriate technical, programmatic, and policy actions to incorporate these findings at state, regional, and national program levels. These TMDL-specific results analyses supplement the national tracking of broader water program measures carried out under the EPA Strategic Plan.

The Clean Water Act's impaired waters program pipeline (above) is a simplified graphical representation of how impaired waters are restored. The pipeline's programmatic stages include:

  • listing (identifying impaired or 303(d) waters and the causes of their impairments),
  • planning (development of the TMDL, TMDL alternative, and/or Implementation Plan),
  • implementing (applying controls, i.e., point source permits or nonpoint source Best Management Practices (BMPs)),
  • improving (making incremental progress in environmental condition but still short of water quality standards), and
  • recovery (fully meeting water quality standards).

Although the primary role of EPA’s TMDL Program is limited by statute to the first two stages of the pipeline, delegated state, tribal and territorial TMDL programs carry on the latter three stages with EPA assistance. TMDL Program results analysis has intentionally focused on program results at all five stages to learn about progress and the effects of EPA’s programs at each stage. This Web site’s structure is based on the pipeline concept, with a subpage of results analysis products and resources for each stage. Broader, overview products that address most or all of the stages are listed below.

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Resources of Interest:

You will need Adobe Reader to view some of the files on this page. See EPA's PDF page to learn more.

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