On April 21, 2014, US EPA and the US Army Corps of Engineers issued a proposed rule to redefine “waters of the United States” under the Clean Water Act (CWA). As previously reported here, the proposed rule has come under intense scrutiny for its apparent expansion of CWA jurisdiction. Now, recent reports published by US EPA’s Science Advisory Board (SAB) recommend that the rule go even further. The SAB’s advice could encourage US EPA to adopt a definition for “waters of the United States” that is even more expansive than the proposed rule.

The SAB issued a final report on the scientific merit of US EPA’s proposed “waters of the United States” definition on September 30, 2014. And then, on October 17, 2014, the SAB issued another report supporting the scientific analysis underlying the proposed rule. Together, the SAB reports are an influential stamp of approval for much of US EPA’s proposed rule, including the rule’s controversial inclusion of tributaries and adjacent waters and wetlands. The SAB states: “the available science supports the conclusion that the types of water bodies identified as waters of the United States in the proposed rule exert strong influence on the physical, chemical, and biological integrity of downstream waters.”

However, the SAB didn’t stop there. The SAB also recommends that US EPA reconsider the proposed rule’s exclusions for certain water bodies, stating the “exclusions of groundwater and certain other exclusions listed in the proposed rule . . . do not have scientific justification.” In addition to groundwater, SAB believes ditches, gullies, rills, non-wetland swales, artificial lakes, and reflection pools should not be categorically excluded. The SAB argues that even these waters may provide important physical, chemical, and biological connections with downstream waters.

Furthermore, the SAB advises US EPA that many other regional and similarly situated waters should be included as “waters of the United States.” In particular, the SAB highlights “Carolina and Delmarva Bays, Texas coastal prairie wetlands, prairie potholes, pocosins, western vernal pools” as water bodies which should be considered waters of the United States.

The SAB’s advice will be strongly considered by US EPA, and could indicate that US EPA will adopt a final definition of “waters of the United States” that either adheres to or expands upon the proposed rule despite significant criticism – including some Congressional criticism – that the proposed rule already exceeds the Agencies’ authority conferred by Congress under the CWA. The public comment period for the proposed rule was recently extended through November 14, 2014. To date, over 218,000 comments have been received.