A proposal to greatly expand the feder­al government’s auth­ority to regulate waterways will negatively affect farmers’ livestock and crop operations as well as their conservation efforts, members of the Iowa Farm Bureau Federation’s (IFBF) 2014 Ag Leaders class told lawmakers last week in Washington, D.C.

The Environmental Protection Agency (EPA) and Army Corps of Engineers earlier this year issued a revised definition of "waters of the U.S." (WOTUS), describing what waters can be regulated under the Clean Water Act. Farmers and other trade groups oppose the proposal, saying the definitions are too vague and would expand the government’s jurisdiction from navigable waters to virtually every ditch, gully or field depression that occasionally contains water.

"Looking at some of the maps on my farm (that would be affected by the new definitions), they’re not navigable waters in any way, shape or form," said Brad...