Water: Module 5
Basic Course: Key Concepts (Module 5.j)
Variances: When Allowed
- 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/Tribes must use one of the six factors listed below (listed in 40 CFR 131.10(g)) to demonstrate that the designated use is not feasible to attain in the short term.
- Factors for Establishing the Basis for Granting a Variance
- Naturally occurring pollutant concentrations.
- Dams or other hydrologic modifications.
- Natural, ephemeral intermittent low-flow.
- Natural physical conditions preclude attainment of aquatic life uses.
- Human-caused conditions or pollutant sources that cannot be remedied or would cause more environmental damage to correct than to leave in place.
- Substantial and widespread economic and social impact.
Question. Can you guess which of the six factors is most commonly used to justify a variance?
Answer. While any of the six factors can be used, in practice, the "substantial and widespread economic impact" factor is most commonly used to justify a variance.