ok-2264: Department of Environmental Quality — Oklahoma's Water Quality Standards

Summary

The gist of this rule and the underlying reason for the rulemaking is to comply with the Water Quality Standards Triennial Review and includes the following updates: add, remove and/or modify certain definitions; update Primary Body Contact Recreation by replacing confidence intervals with geometric mean and statistical threshold values, applicable to both E. coli and Enterococci; updating Secondary Body Contact Recreation to add numeric criteria for E. coli and enterococci based on EPA’s water ingestion formula; adding the designation of Culturally Significant Waters to 5 waterbodies at the request of the Quapaw Nation; adding language requiring the use of the copper biotic ligand model for development of copper site-specific criteria; requiring the use of a fish tissue study for selenium site-specific criteria; removal of the option for WER for site-specific criteria for copper; removal of site-specific metals criteria that were not approved by EPA; removal of segment averages that were not approved by EPA; recalculation of certain criteria and the addition of Aquatic Life and Human Health criteria values based on EPA’s recommended values; and, including an updated version of Appendix H that was missing in the most recent version of Chapter 730.

The agency’s own summary, as published.