EPA and ACOE Propose a Definition of “Waters of the United States” That Is Adaptive to Climate Change

On December 7, 2021, the Environmental Protection Agency (EPA) and Army Corps of Engineers (ACOE) proposed a revised definition of "waters of the United States” that allows for consideration of the effects of climate change on water resources when determining federal jurisdiction under the Clean Water Act. As explained in the proposed rule, “[t]his term establishes the extent of most federal programs to protect water quality under the [Clean Water] Act—including, for example, water quality standards, impaired waters and total maximum daily loads, oil spill prevention, preparedness and response programs, state and tribal water quality certification programs, and dredged and fill programs—because such programs apply only to ‘waters of the United States.’”

In the proposed rule, EPA and ACOE interpret the term ‘‘waters of the United States’’ to include: “Traditional navigable waters, interstate waters, and the territorial seas, and their adjacent wetlands; most impoundments of ‘waters of the United States’; tributaries to traditional navigable waters, interstate waters, the territorial seas, and impoundments that meet either the relatively permanent standard or the significant nexus standard; wetlands adjacent to impoundments and tributaries, that meet either the relatively permanent standard or the significant nexus standard; and ‘other waters’ that meet either the relatively permanent standard or the significant nexus standard.” The agencies specify that “the ‘significant nexus standard’ means waters that either alone or in combination with similarly situated waters in the region, significantly affect the chemical, physical, or biological integrity of traditional navigable waters, interstate waters, or the territorial seas.” The agencies further specify that the significant nexus standard allows them to consider climate change when evaluating if upstream waters significantly affect foundational waters.

EPA and ACOE are accepting comments on the proposed rule received on or before February 7, 2022.