They are getting a little carried away with their jurisdiction, imagine that.
Check it out:

In enforcing the Clean Water Act (CWA), the US Environmental Protection Agency (EPA) and the US Army Corps of Engineers (COE) have clear jurisdiction over “[1] traditional navigable waters; [2] interstate waters, including interstate wetlands; [3] the territorial seas; [and 4] impoundments of traditional navigable waters, [and] interstate waters, including interstate wetlands, [and] the territorial seas.” The further upstream a water body, intermittent stream, or wetland is from one of these, the less clear it becomes that the EPA and the COE have jurisdiction.

This lack of clarity has resulted in lawsuits on behalf of landowners, several of which have ended up before the US Supreme Court. In the 2001 and 2006 cases, justices argued that there must a “significant nexus” between other waters and those over which the agencies have clear jurisdiction for the agencies to exercise regulatory control. The purpose of the April 21, 2014 proposed rule, “Definition of ‘Waters of the United States’ Under the Clean Water Act,” is in part to clarify what that “significant nexus” is and what waters would fall under the jurisdiction of the EPA and/or the COE. All quoted material in this article comes from the Proposed Rule.