Basic Course: Key Concepts

Parameters:  Existing Uses (Tier 1)

Tier 1 of the State or Tribe’s antidegradation program must protect existing uses by maintaining the water quality necessary to support those uses. Tier 1 is applicable to all surface waters.

Existing uses are determined by considering data on both the use that has occurred and the water quality that has been achieved to support the use.

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