Permitting Strategies & Reasonable Potential Analysis

Water quality based limitations (WQBLs) are imposed in wastewater permits when it is determined that technology based limitations are not sufficient to protect water quality (40 CFR 125.3). These limitations are based on state and federal water quality standards, as well as the assimilative capacity of the receiving stream.

EPD has developed a number of permitting strategies and reasonable potential analysis procedures to aid in the determination of effluent limitations in NPDES wastewater permits. More information on the development of limitations may be found on the Water Quality Modeling page.

NPDES Reasonable Potential Procedures

Specific analyses and strategies are listed below for the following:

• Ammonia
• Phosphorus
• Total Residual Chlorine
• Whole Effluent Toxicity

Ammonia

• Ammonia NPDES Strategy
• Flexibilities for States Applying EPA’s Ammonia Criteria Recommendations (EPA-820-F-13-001)
• Ammonia Reasonable Potential Analysis Procedure for NPDES Permits, May 2017
• Example Reasonable Potential Analysis Worksheet
• Sample Permit Conditions Ammonia Compliance Schedule and Recalculation Procedure – Industrial
• Sample Permit Conditions Ammonia Compliance Schedule and Recalculation Procedure – Municipal

Phosphorus

• Phosphorous Strategy

Total Residual Chlorine

• Total Residual Chlorine Strategy

Whole Effluent Toxicity

• WET Strategy
• WET Memo