Water Quality Standards for the State of Missouri's Lakes and Reservoirs

The Environmental Protection Agency (EPA or Agency) proposes to establish federal nutrient criteria to protect designated uses for the State of Missouri's lakes and reservoirs. On August 16, 2011, EPA disapproved most of the numeric criteria for total nitrogen, total phosphorus, and chlorophyll a that the State submitted to EPA in 2009. EPA acknowledged the importance of Missouri's proactive efforts to address nutrient pollution by adopting numeric nutrient criteria. However, EPA concluded that the Missouri Department of Natural Resources (MDNR) had failed to demonstrate the criteria would protect the State's designated uses and were not based on a sound scientific rationale. The Clean Water Act (CWA) directs EPA to promptly propose water quality standards (WQS) that meet CWA requirements if a state does not adopt WQS addressing EPA's disapproval. On February 24, 2016, the Missouri Coalition for the Environment (MCE) filed a lawsuit alleging that EPA failed to satisfy its statutory obligation to act "promptly." On December 1, 2016, EPA entered into a consent decree with MCE committing to sign a notice of proposed rulemaking by December 15, 2017 to address EPA's 2011 disapproval, unless the State submits and EPA approves criteria that address the disapproval on or before December 15, 2017. As of the date of this proposed rule, Missouri has not submitted new or revised standards to address EPA's 2011 disapproval and EPA has not approved such water quality standards. Therefore, under the terms of the consent decree, EPA is signing a notice of proposed rulemaking that proposes new water quality standards addressing EPA's August 16, 2011 disapproval. In this proposal, EPA seeks comment on two primary alternatives. Under the first alternative, EPA proposes nutrient protection values and eutrophication impact factors in a combined criterion approach. Under the second alternative, EPA proposes a similar combined criterion approach that would mirror the State of Missouri's October 2017 proposal for lake nutrient water quality standards. EPA will not proceed with final rulemaking (or will withdraw its final rule, if applicable) to address its 2011 disapproval if Missouri adopts and submits criteria to address EPA's 2011 disapproval and EPA approves them as meeting CWA requirements.