June 5, 2018
EPA's Modeling Approach to Metals Criteria: How May it Affect State Water Quality Criteria?
Speaker: Lial Tischler, Partner, Tischler/Kocurek
The U.S Environmental Protection Agency (EPA) has for over ten years been evaluating, proposing, and in the case of fresh water aquatic life criteria for copper, adopting revised approaches to calculating criteria using modeling methodologies that calculate criteria using site-specific data for water chemistry that effect the aquatic toxicity of metals. EPA believes these model-based methodologies are more protective than its 1985 methodology that has been used to develop all existing water quality criteria for metals that have been adopted by the states, sometimes with state-specific changes. This paper will discuss the implications of changing aquatic life water quality criteria for metals on water quality-based effluent limits (WQBELs) for dischargers. For example, EPA Region 6 has recently implemented a policy to evaluate the protectiveness of site-specific water quality criteria for copper developed with the water effects ratio (WER) method using the fresh water copper BLM.