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Water: Module 5

Basic Course: Key Concepts (Module 5.j)

Variances: When Allowed

Module 5. Water Quality Flexibilities

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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
    1. Naturally occurring pollutant concentrations.
    2. Dams or other hydrologic modifications.
    3. Natural, ephemeral intermittent low-flow.
    4. Natural physical conditions preclude attainment of aquatic life uses.
    5. Human-caused conditions or pollutant sources that cannot be remedied or would cause more environmental damage to correct than to leave in place.
    6. Substantial and widespread economic and social impact.
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Question. Can you guess which of the six factors is most commonly used to justify a variance?


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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.

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

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