The Evolution of the “Waters of the United States” and the Role of Economics

The Clean Water Act (CWA) of 1972 seeks to “restore and maintain the chemical, physical, and biological integrity of the Nation’s waters” (US EPA 2002, 3). The CWA describes broad goals concerning the quality of the nation’s waterways, the administrative roles of the federal government and states, and many other features of pollution control that target the discharge of pollution into “navigable waters.” Near the end of the statute, the CWA states: “The term ‘navigable waters’ means the waters of the United States, including the territorial seas” (US EPA 2002, 214). The law provides no further definition of navigable waters, “waters of the United States” (WOTUS), or “the nation’s waters.” Fifty years later, Congress has yet to clarify the meaning of these phrases. This lack of clarity about where and to which types of “wa-ters” the CWA applies has led to decades of litigation, several Supreme Court decisions, and recent policy whiplash as the Obama and Trump administrations passed rules that alternated between comprehensive and very limited definitions of WOTUS. The Biden administration has signaled an intent to find a middle ground. In this article, we review the complicated history of WOTUS, describe the role that economics has played in recent debates about the definition and regulation of WOTUS, examine key issues for the Biden administration to consider as it works to develop a new rule, and highlight research priorities for economists seeking to inform the debate about WOTUS.