The Environmental Protection Agency’s and Army Corps of Engineers’ proposed changes to the definition of “waters of the United States” (WOTUS) in the Clean Water Act “decreases protection for our nation’s waters and does not support the objective of restoring and maintaining ‘the chemical, physical and biological integrity’ of these waters,” as stated in the CWA, EPA’s Science Advisory Board said in comments released Dec. 31.

The board, whose members are scientists outside the agency, said EPA’s latest proposal “neglects established science pertaining specifically to the connectivity of groundwater to wetlands and adjacent major bodies of water.” In particular, EPA did not take into account findings regarding “watershed systems and processes” in EPA’s 2015 Connectivity Report.

The proposal's "departure ... from EPA-recognized science" also threatens to weaken protection of the nation’s waters "by failing to protect ephemeral streams and wetlands which connect to navigable waters below the surface,” the SAB said in its eight-page critique. Those changes do not have “a fully supportable scientific basis” and have the potential to introduce “substantial new risks to human and environmental health.”

“There is no scientific justification for excluding groundwater from WOTUS if spring-fed creeks are considered to be jurisdictional," the board said. "The chemical or biological contamination of groundwater may lead to contamination of functionally connected surface water.”

Ag groups have pushed for a simplification of WOTUS through the Trump administration's rulemaking, saying a producer should be able to visually detect if they have a navigable water from their vehicle rather than through more advanced means. 

EPA has sent the final version of its WOTUS rule to the Office of Management and Budget for review, where it has been the subject of numerous meetings requested by environmental and industry groups, including the American Farm Bureau Federation and Natural Resources Defense Council. EPA and the Army Corps of Engineers are expected to publish the rule this month, according to EPA’s regulatory agenda. NRDC attorney Jon Devine, who attended a Dec. 18 meeting at OMB, said he saw “no indication that the administration intends to change course from abandoning decades-old protections for water bodies.”

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