Farm leaders, ag officials, home builders and others told congressional leaders in Iowa last week that a return to the expansive Obama-era water rules would be devastating to agriculture, construction and a wide swath of the U.S. economy.

“This is not just an ag issue. It affects every part of our economy,” said Mike Naig, Iowa secretary of agriculture. “We need certainty in our water rules, and it appears we could be taking a step backward into another era of uncertainty.”

Naig and others were speaking to a roundtable held by the Congressional Western Caucus at the Iowa Farm Bureau Federation headquarters in West Des Moines. Washington Rep. Dan Newhouse, chair of the Western Caucus, led the roundtable and was joined by Iowa Rep. Mariannette...