Water: Module 5
Basic Course: Key Concepts (Module 5.a)
Introduction: Flexibility Mechanisms in Water Quality Protection
- Module 1: Overview
- Module 2: Use
- Module 3: Criteria
- Module 4: Antidegradation
- Module 5: Flexibilities
- Flexibility Mechanisms in Water Quality Protection
- CWA Goals
- Feasibility of Controls
- Feasibility Factors
- The Economic Factor
- Potential Parameters
- Addressing Local Conditions
- When Site-Specific Criteria Are Allowed
- Temporary Modification to Water Quality Standards
- When Variances Are Allowed
- Discharger Grace Period
- Module 6: Review
- Certificate of Completion
States or authorized Tribes have different approaches for addressing particular water quality-related circumstances:
|Need for designated use removal/revision||Standards||Use attainability analysis|
If a State/Tribe finds that attaining one of the designated uses in its standards is not feasible, it can be changed or removed based on appropriate analysis and documentation subject to EPA review and approval.
|Need to address waterbody specific conditions||Criteria||Site-specific criteria|
In addition to the ability to revise designated uses, States/Tribes may establish site-specific criteria where it identifies conditions in a water body that differ from national criteria (e.g., naturally occurring pollutant concentrations in a stream segment that exceed the national criteria for aquatic life uses). The State/Tribe must follow established protocols/procedures for establishing the criteria, which are adopted then subject to EPA review and approval.
|Need for discharger or State/Tribe to evaluate whether a designated use and associated criteria are appropriate and attainable.||Individual or multiple dischargers||Variance|
If an individual or group of dischargers determine they cannot meet their current permit limit immediately but are also uncertain whether they can ultimately meet it, a permitting authority can grant a variance. This temporarily modifies the standards, usually for a specific pollutant with all other underlying standards remaining in place. The State/Tribe must follow its established variance policies, and the variance is then subject to EPA review and approval.
|Need for discharger grace period to meet permit limits based on new/revised criteria||Individual discharger||NPDES permit compliance schedule|
If an individual discharger requests additional time to comply with a permit limit based on new or revised criteria, a permitting authority can include a compliance schedule as part of the discharger’s NPDES permit. When deciding to grant the compliance schedule, the State/Tribe’s water quality standards (or implementing regulations) must specifically authorize the use of compliance schedules in NPDES permits and be consistent with EPA's regulations.