Modifications to Water Quality Standards

Temporary Modifications to Water Quality Standards

Water Quality Variance

Situations can arise in which an individual or group of dischargers determine they cannot immediately meet their permit limits. For such situations, the regulations afford the flexibility to adopt a variance that temporarily modifies the water quality standards to the highest use and criteria that are currently available. This variance of the use and criteria then serves as the basis for the permit limits that a discharger can meet for the duration of the variance.

In granting the variance, the State must follow its established variance policies and the variance is subject to public and U.S. EPA review. One or more of the six factors listed in 40CFR131.10(g) must be used to demonstrate that the designated use is not feasible to attain in the short term.

Current U.S. EPA Approved Water Quality Variances

Location Parameter Alternative Criteria Use Category 47CSR2 Source
Martin Creek of Preston County and its tributaries pH, total iron, dissolved aluminum pH range of 3.2-9.0, 10 mg/L total iron, 15 mg/L dissolved aluminum B1, B2, B4, C, A 7.2.d.8.2

Permanent Modifications to Water Quality Standards

Site Specific Criteria

States may establish site-specific criteria where it identifies conditions in a water body that differ from state criteria and reflect local environmental conditions. A site-specific criterion is intended to come closer than the state standard to providing the intended level of protection to the aquatic life at the site, usually by taking into account the biological and/or chemical conditions at the site. Site-specific, as with all water quality criteria, must be based on a sound scientific rationale in order to protect the designated use.

Current U.S. EPA Approved Site-Specific Criteria

Location Parameter Alternative Criteria 47CSR2 Source
Marr Branch Dissolved Zinc Hardness Based Equation
CMC=CCC=e0.8541*In(hardness) + 1.151 X CF
Opequon Creek Aluminum 500 ug/L 7.2.d.2.1
Unnamed Tributary of Daughtery Run Iron 3.5 mg/L 7.2.d.8.1
Fly Ash Run Aluminum (acute)
Al - 888.5 ug/L
Mg - 5 mg/L
Conners Run Selenium
Se - 62 ug/L
Fe - 3.5 mg/L (monthly average)
Fe - 7 mg/L (daily average)
Little Scary Creek Selenium
Se - 62 ug/L
Cu - 105 ug/L (daily average)
Cu - 49 ug/L (four day average)

Use Reclassification

A designated use and its supporting criteria can be removed/revised from water quality standards when it is determined that attaining the use is not feasible. The revision/removal must be supported with appropriate analysis and documentation.

Current U.S. EPA Approved Use Reclassifications

Location Reclassification 47CSR2 Source
Daugherty Run Removal of public water supply use (Category A) 7.2.d.8.1
Fly Ash Run Removal of public water supply use (Category A) 7.2.d.8.1
Conners Runs Removal of public water supply use (Category A) 7.2.d.16.1
Little Scary Creek Removal of public water supply use (Category A) 7.2.d.20.2
Pats Branch Removal of public water supply use (Category A) and irrigation (Category D1) uses 7.2.d.34.1​