On May 27, 2015 the EPA and the Corps of Engineers issued a prepublication version of its final rule to define "waters of the United States" 40 CFR 230. Soon the final rule will be published in the Federal Register and will take effect sixty days after publication.

The regulated community will likely mount a judicial challenge to this rule and Congress may pass legislation disapproving the final rule; however, President Obama would veto any such legislation and it would be difficult to overcome his veto (takes a 2/3 vote of both houses of Congress).

The definition of "waters of the United States" has been subject to numerous judicial challenges in the past. In Rapanos v. United States, 547 U.S. 715 (2006), the Supreme Court majority found the need to determine whether a water body had a "significant nexus" to downstream traditional navigable waters to be encompassed by the Clean Water Act. While the EPA and Corps of Engineers had guidance on determining "waters of the United States," rulemaking makes a binding rule to determine coverage. If wetlands, a tributary or water body is covered by the rule, land disturbing activities will require permitting and mitigation of impacts to the affected water body.

The EPA has summarized the rule's effects as follows:

1. Traditional Navigable Waters, Interstate Waters, Territorial Seas and Impoundment of Jurisdictional Waters have always been considered by the federal agencies to be regulated and no change is made by this final rule.
2. The definition of "tributaries" to navigable waters are characterized by the presence of physical indicators of flow—such as bed and banks and ordinary high water marks that contribute (directly or indirectly) to a navigable water. Some ditches will be covered by this rule, but ditches that only flow after a rain event are not covered by the rule.
3. "Adjacent Waters" include wetlands, ponds, lakes and impoundments that are adjacent, contiguous or neighboring a navigable waterway and are also considered to be regulated. Certain farming and ranching activities (defined by Section 404(f) of the Clean Water Act) are still exempt from regulations.
4. "Neighboring" a navigable waterway is further defined as: (a) waters located within one hundred feet of a traditional navigable waterway; (b) waters in the 100-year floodplain that are within fifteen hundred feet of the navigable waterway's high water mark; and (c) waters within fifteen hundred feet of the high tide of a navigable waterway or the high water mark of the Great Lakes.

There are specific discussions of items such as Carolina bays and Texas coastal prairie wetlands. Case-specific "significant nexus" analysis will be required for all waters within a 100-year floodplain of a navigable waterway and within four thousand feet of the high water mark of a traditional navigable waterway.

This is just a summary of a very important and expansive ruling on federal jurisdiction of waterways and wetlands for permitting and mitigation. Future litigation will no doubt change or modify portions of the final rule.