Addressing stream-flow problems

To the extent that flow impairments damage habitat and cause harm to aquatic life, listing and TMDL development may be warranted. EPA has interpreted the regulations to mean that TMDLs are required only for pollutants (40CFR130.7(c)(1)(i)). EPA guidance states that if only low flow threatens or impairs a water body, a TMDL is not required. It belongs in Category 4 of the 303(d) list.

“EPA does not believe that flow, or lack of flow, is a pollutant as defined by CWA Section 502(6). Low flow can be a man-induced condition of a water body (i.e., a reduced volume of water) which fits the definition of pollution. Lack of flow sometimes leads to the increase of the concentration of a pollutant (e.g., sediment) in a water. In the situation where a pollutant is present, a TMDL, which may consider variations in flow, is required for that pollutant.”

(Guidance for 2004 Integrated Report)

Waters with flow impairments are therefore likely to end up in “Category 4: Water is impaired or threatened, but a TMDL is not needed."

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