On June 29, 2015, the U.S. Environmental Protection Agency and the U.S. Army Corps of Engineers jointly published a final rule, “Definition of ‘Waters of the United States’ Under the Clean Water Act,” to clearly delineate how the Clean Water Act protects streams and wetlands. The new Waters of the United States rule (“WOTUS Rule” or the “Rule”) abrogated the previous definition of waters of the United States under Clean Water Act jurisdiction. To the great displeasure of many private landowners, the Rule entered into effect on August 28, 2015. In particular, several critics have argued that the new WOTUS Rule’s regulation of “other waters,” its definition of “adjacent,” and its expanded construction of the term “tributary” violate the Commerce Clause of the U.S. Constitution. Examining select, representative challenges by the National Association of Homebuilders, the Kansas Livestock Association, and the National Cattlemen’s Beef Association, this Note argues that those three features of the new WOTUS Rule do not, as alleged, contravene the Commerce Clause. As a matter of Commerce Clause jurisprudence, the new WOTUS Rule is a legal tool to aid the federal government in its fight against the degradation and pollution of our nation’s waters.