Donna Downing, Jurisdiction Team Leader, Wetlands Division, U.S. EPA, discussed the need to clarify some of the definitions in the Clean Water Act. “Congress did not define in the CWA what it meant by ‘waters of the U.S.,’” Downing said,   “and left it up to EPA and the Army Corps of Engineers to provide more detail through rulemaking. The agencies issued regulations shortly after the statute was enacted in 1972, and the current regulatory definition is essentially unchanged since the late 1970s.”

Covered waters include interstate waters, territorial seas, impoundments, and tributaries—which now has a more limited definition that includes: “a bed and banks and high water marks. A wetland may be a tributary if it is near a river or stream and contributes flow to that stream.”

A covered tributary also contributes flow to a traditional navigable water (TNW), interstate water, or territorial sea either directly or through other waters.  Wetlands are tributaries even where lacking a bed and banks and ordinary high water mark (OHWM) if they contribute flow to such waters.

The definition also emphasizes that tributaries can be natural, man-made, or man-altered.  This includes ditches that meet the definition of tributary and are not excluded in the “Waters Not Waters of the U.S.” section.

Downing said the new definition “limits (not expands) the scope of what is jurisdictional as a tributary under the regulations.”

A category tagged “adjacent waters,” also leaves room for clarification. “Existing regulations define ‘adjacent’ as “bordering, contiguous, or neighboring,” Downing said.  “That regulatory definition is unchanged, and the proposal defines ‘neighboring’ for the first time.  Defining neighboring enhances clarity.  Floodplains and riparian areas are defined as ‘neighboring’ under the proposal.  This means that wetlands, lakes, and ponds located in those areas are adjacent, not that the floodplain or riparian is itself WUS.”

Other waters “require a case-by-case analysis to determine if they are protected or not,” Downing said.

“Non-jurisdictional waters, those not covered, include prior converted cropland—a concept created under the Food Security Act years ago and includes areas used to grow commodity crops before November 1985.   “Current regulations list PCC as exempt from the definition of WUS, and the proposal retains that exemption without discussion.”

Waters that do not fall into the categories above are jurisdictional only where case-specific analysis shows that they have a significant nexus (connection) to a TNW, interstate water, or territorial sea,” Downing explained. “Other waters must have a significant connection to another TNW to be considered covered.”