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Water: Module 4

Basic Course: Key Concepts (Module 4.b)

Policy Statement: A General Framework

Module 4. Antidegradation Requirements

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In essence, a State or Tribe's antidegradation policy provides a framework for weighing the pros and cons of a proposed activity that could degrade water quality and for involving the public in the decision-making (40 CFR Section 131.12(a)).


Key Point. Within limitations established by EPA's regulations, the State or authorized Tribe has the discretion to permit activities that degrade water quality to a minimum level—that is, to the level of quality identified in the State or Tribe's water quality standards as being necessary to support the water body's existing uses.

Antidegradation policy can apply to both point and non-point source activities.


Key Point. Before permitting degradation for point sources, the State/Tribe must ensure that the most stringent technology-based controls required by statute and regulation will be implemented.

Because the Clean Water Act does not authorize regulatory non-point source control programs, EPA cannot require States/Tribes to implement such programs. States/Tribes, of course, are free to adopt requirements for non-point sources that exceed those of the CWA. Nonetheless, where States/Tribes have established an approach for evaluating non-point sources, the process must be followed before allowing degradation of water quality.


Key Point. Before allowing an increase in pollutant loads by non-point sources, the States/Tribes with a non-point source control program should ensure that reasonable and cost-effective best management practices for control will be implemented.

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

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