Section 401 of the Clean Water Act requires that a facility requiring a federal license, such as a nuclear power plant, must receive state water quality certification when it engages in activities “which may result in any discharge” into lakes and rivers. In this case, the Supreme Court will decide whether water flowing through hydroelectric dams constitutes a “discharge.” Petitioner Warren argues that the mere flow of water through an existing dam does not constitute a discharge on the grounds that the Supreme Court had previously held in the Miccosukee case that the term “discharge” requires an addition of water to the existing flow from a distinct body of water, and thus does not refer to the removal and replacement of water from and to the same body of water. Florida Water Mgmt. Dis. v. Miccosukee Tribe, 541 U.S. 95 (2004). Respondent Maine Board of Environmental Protection and other respondents contend that state water quality certification is required for dams because the definition of discharge used in the Miccosukee case can be distinguished from this case via two main avenues. First, respondents argue that Miccosukee dealt with Section 402 of the Clean Water Act, and is not necessarily binding in this case. Congress’ intent in enacting Section 402, respondents argue, was to regulate pollutants added to the nation’s waters, while Section 401 was aimed at water regulation generally and as such the definition of discharge in Section 401 includes water flowing through dams. Respondents also attempt to distinguish the Miccosukeerequirement of an addition of water to the existing flow of water by interpreting “discharge” under the plain meaning of the term. The definition of “discharge,” respondents claim, includes the Miccosukee requirement, but is not limited by it; hydroelectric dams are thus subject to state regulation because the more expansive plain meaning of “discharge” includes the discharge of water from a dam even without an addition to the flow. The resolution of the conflicting definitions followed by Miccosukee and state environmental protection boards will have far-reaching effects on the profitability and efficiency of hydroelectric dams throughout the nation, energy production generally, and the environment.