Last year, U.S. EPA and the Army Corps of Engineers issued a guidance document addressing the scope of the agencies' jurisdiction under CWA s.404 after the U.S. Supreme Court's decision in Rapanos v. United States. That document has been revised following receipt and review of over 66,000 public comments, and can be found here. Some of the points identified by the agencies as "key" -
The agencies will assert jurisdiction over traditional navigable waters, which includes all the waters described in 33 C.F.R. s.328.3(a)(1), and 40 C.F.R. s.230.3(s)(1); [and,]
The agencies will assert jurisdiction over wetlands adjacent to traditional navigable waters, including over adjacent wetlands that do not have a continuous surface connection to traditional navigable waters.
And don't forget the significant nexus analysis that the agencies will use to assert jurisdiction over certain "non-navigable tributaries" that are intermittent in nature!