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Water: Water Quality Standards Academy

Basic Course: Supplemental Topics - 303(d) Submissions: Integrated Reporting Categories

Listing Impaired Waters and Developing TMDLs

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With the Integrated Report option, EPA encourages States/Tribes to use a five-category system for classifying all water bodies (or segments) within its boundaries regarding the waters' status in meeting the State's/Tribe's water quality standards. The categories are listed below. The classification system uses designated uses as the basis for reporting on water quality.

Category/Subcategory Description
Category 1 All designated uses are supported, no use is threatened.
Category 2 Available data and/or information indicate that some, but not all, designated uses are supported.
Category 3 There is insufficient available data and/or information to make a use support determination.
Category 4 Available data and/or information indicate that at least one designated use is not being supported or is threatened, but a TMDL is not needed.
  • Category 4a
A State developed TMDL has been approved by EPA or a TMDL has been established by EPA for any segment-pollutant combination.
  • Category 4b
Other required control measures are expected to result in the attainment of an applicable water quality standard in a reasonable period of time.
  • Category 4c
The non-attainment of any applicable water quality standard for the segment is the result of pollution and is not caused by a pollutant.
Category 5 Available data and/or information indicate that at least one designated use is not being supported or is threatened, and a TMDL is needed.

The waters from Category 5 constitute the Section 303(d) list of impaired or threatened waters within the State/Tribe's boundaries.

Key Point. EPA developed the multi-category classification system to help States/Tribes to report on incremental progress toward attaining water quality standards.
Key Point. States/Tribes may establish additional subcategories to refine their classifications further. For example, under Category 3, subcategories could be used to distinguish between segments for which no data/information is available and segments for which data/information is available but insufficient for making a use-support determination. At the Federal level, EPA has offered Subcategory 5m as a voluntary approach for listing waters impaired by mercury mainly from atmospheric sources.
For national summary information about impaired waters based on biennial reporting, visit EPA's Web site titled National Summary on Impaired Waters and TMDL Information.

For informational purposes only–Not official statements of EPA policy.

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