Whole Effluent Toxicity: A Kentucky Permit Perspective

摘要

The Kentucky Division of Water has incorporated Whole Effluent Toxicity (WET) limits in Kentucky Pollution Discharge Elimination System (KPDES) permits since 1987. Currently there are 90 municipal and 62 industrial facilities with this requirement. The federal authority for WET limits comes from Section 101 (2) (3) of the Clean Water Act (no toxics in toxic amounts). Title 401, Chapter 5:031 of the Kentucky Administrative Regulations (KAR) contains the criteria for the protection of aquatic life and human health (chemical specific and whole effluent toxicity). Permit limits are established for those discharges that have a reasonable potential to cause or contribute to a violation of water quality standards. Once this reasonable potential is determined, WET limits are developed using a steady-state mass balance model. Factors taken into consideration include effluent flow, receiving stream flow, zone of initial dilution (ZID), mixing zone (MZ), and the acute to chronic ratio (ACR). An acute or chronic limit is chosen based on best professional judgment using the ACR as a guide. Once the WET limit is established monitoring requirements and frequency will be assigned based on the facility and its WET history. Test conditions including the determination of complianceon-compliance is detailed in the biomonitoring language part of the permit. Included in this language are the conditions for entering into a Toxicity Reduction Evaluation (TRE).