Science at the boundaries: scientific support for the Clean Water Rule

Abstract

AbstractThe US Environmental Protection Agency (EPA) and US Army Corps of Engineers have promulgated a definitional rule to clarify the scope of “waters of the United States” protected under the Clean Water Act (CWA). The Clean Water Rule, published in June 2015, defines 8 categories of waters for jurisdiction and expressly excludes certain features from jurisdiction, based on law, science, public input, and 40+ y of experience implementing the CWA. It also defines terms used in regulation including, for the first time, “tributary,” “neighboring,” and “significant nexus”. Much of the scientific basis for this rule is contained in a report titled “Connectivity of Streams and Wetlands to Downstream Waters: A Review and Synthesis of the Scientific Evidence” developed by EPA’s Office of Research and Development to inform the rulemaking process. As a scientific review, the report does not consider or set forth legal standards for CWA jurisdiction. Rather, it summarizes current scientific understanding of the c...