Basic Course: Key Concepts (Module 4.d)

Parameters: A Three-Tiered Program

The general parameters of a State or Tribe’s antidegradation program must address three categories.

Tier 1.

Protection of water quality for existing uses.

Tier 2.

Protection of high quality waters.

Tier 3.

Outstanding National Resource Waters.

Key Point. For all tiers, a State or Tribe's review of activities that raise antidegradation considerations should be documented and subject to public review and comment.

At a minimum, States/Tribes must apply their antidegradation program to activities that are regulated under State, Tribal, or federal law, including:

• Any activity that requires a permit or water quality certification.
• Any activity subject to State/Tribal non-point source control requirements or regulations.
• Any activity that is otherwise subject to State/Tribal regulations specifying that water quality standards are applicable.

Key Point. Federal antidegradation requirements do not create State/Tribal regulatory authority over otherwise unregulated activities.