The Environmental Protection Agency needs to explain the intentions behind a proposed rule that Republicans say could subject massive amounts of private property to federal regulation, a GOP House committee chairman said.

The release of federal maps highlighting waters in the United States, excluding wetlands, raises suspicions about the EPA's push to more clearly define which bodies of water fall under Clean Water Act jurisdiction, said House Science, Space and Technology Committee Chairman Lamar Smith, R-Texas.

"These maps show the EPA's plan: to control a huge amount of private property across the country," the Texas Republican wrote in a Wednesday *letter to EPA Administrator Gina McCarthy.

But the agency said the maps aren't related to the proposed Waters of the U.S. rule, to which Smith was referring.

"Let us be very clear — these maps have nothing to do with EPA’s proposed rule or any other regulatory purpose. They were first created during the Bush administration to identify waters that would be vulnerable as a result of a 2001 Supreme Court case and pending litigation. The maps were subsequently updated to reflect new data and a 2006 Supreme Court decision," the EPA told the Washington Examiner in an email.

House Republicans, hearing concerns from farmers, ranchers and others in the agricultural community, have made the proposed rule a focal point. They have called it a land grab, and it has served as a symbol for what they have called regulatory overreach by the EPA in a number of economic sectors.

The EPA says the Waters of the U.S. rule would provide clarity regarding the streams and other bodies of waters it already regulates to protect drinking water from pollution. The current process requires people to ask federal agencies to do a field survey to determine whether an upstream body of water — say, a wetland — falls under regulation. Under the proposed rule, waters directly connected to navigable waters — such as streams and rivers — would fall under federal regulation.

Nancy Stoner, EPA's acting assistant administrator for water, in a July 28 letter to Smith said the maps she was providing him — and that he later posted on his committee's website — were compiled using federal data on water resources, but that it did not detail waters jurisdictional under the Clean Water Act.

"While there are maps depicting water resources on both a national and state scale maintained by multiple agencies, I wish to be clear that EPA is not aware of maps prepared by any agency, including the EPA, of waters that are currently jurisdictional under the [Clean Water Act] or that would be jurisdictional under the proposed rule," Stoner said.

The effort has struck nerves among farmers, ranchers and others on two points.

One is that the EPA, heeding the instruction of separate Supreme Court rulings, is including bodies of water that have "a significant nexus," but are not necessarily directly connected to, streams, rivers and other navigable waters. The Army Corps of Engineers would decide on a case-by-case basis whether specific waters are subject to regulation.

The second point of contention is an itemized list of agricultural practices that are exempted from the regulation. The EPA and its supporters contend that offers certainty, but the agricultural community has focused on what's not on the roster.

All that has amounted to consternation about whether farmers, small businesses and others will have to apply for permits, or face lawsuits, for activities they have long thought were acceptable.