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Impaired Waters and TMDLs

Impaired Waters Restoration Process: TMDL Implementation

The majority of TMDLs have been developed since the turn of the century. The development of large numbers of TMDLs is relatively recent -- most TMDLs are just a few years old. Although large numbers of TMDLs exist, there has been uncertainty about how many have been implemented. Implementing a TMDL for an impaired water body involves applying the pollution control practices necessary to reduce the pollutant loads to the extent determined necessary in the TMDL. These practices usually consist of point source control permits and/or non-point source control Best Management Practices (BMPs).

Because there are often numerous control practices involved in a single TMDL's implementation, it would be particularly complex and expensive for states or EPA to track all implementation actions under all TMDLs. Moreover, whereas EPA oversees and approves TMDL development by states, the CWA does not require nor does the Agency have authority over their implementation. Nevertheless, states and EPA alike recognize TMDL implementation as a crucial stage en route to impaired waters restoration.

States can set restoration priorities among large numbers of impaired waters through using recovery potential screening. Recovery Potential Screening is an applied set of tools, techniques and reference information to help states and others compare the restorability of their impaired waters to inform strategies for earlier and greater success in restoration.

Reports and Resources