Republican lawmakers warned Wednesday that a complex EPA proposal in the works would give the federal government "free reign" to regulate virtually any waterway or wetland in the country. 

In a rare joint House-Senate hearing, EPA Administrator Gina McCarthy was called to explain the plan, which has prompted complaints from farmers and agriculture groups, as well as local environmental officials who worry the EPA is claiming authority that should be left to the states. 

House transportation committee chairman Rep. Bill Shuster, R-Pa., said that if the policy takes effect, "It will open the door for the federal government to regulate just about any place where water collects." 

Shuster claimed the proposal would "trample the rights" of state governments and hurt the middle class by driving up prices through additional regulation. 

"This rule is an end-run around Congress and another example of overreach by the administration," he said.   

Since 2013, the EPA has floated new rules that would define what kinds of waterways fall under its jurisdiction. The Clean Water Act already gives the EPA the ability to regulate "U.S. waters," but Supreme Court rulings have left the specifics unclear when it comes to waters that flow only part of the year. 

To address that, the EPA and Army Corps of Engineers want to define that authority -- and are eyeing waterways deemed to have some significant connection to major rivers, lakes and other systems. This would include, according to the EPA, "most seasonal and rain-dependent streams" as well as wetlands near rivers and streams. The EPA has assured, though, that most farming activity would not require a permit. 

The EPA is planning to release a final rule in the spring of this year. 

McCarthy said Wednesday that the point is to make the rules "easier to understand" and more "consistent." She said the EPA is working to address the concerns of farmers and others, and stressed that the final rule "will not change in any way" those who are already exempted from the Clean Water Act. Speaking to farmers' concerns, she said the new plan would even reduce the law's jurisdiction over features like ditches. 

"We are in fact narrowing the jurisdiction of the Clean Water Act," McCarthy said. EPA officials clarified at Wednesday's hearing that groundwater would not be covered under the new rule, potentially allaying some concerns. 

But several GOP lawmakers were not convinced, worried that the new EPA language would be used to force people and businesses to obtain "costly permits" for their land. Sen. John Barrasso, R-Wyo. -- citing the case of a Wyoming family that was threatened with $75,000 a day in fines over a stock pond built on their property without a federal permit -- said he would introduce legislation along with Sen. James Inhofe, R-Okla., to "stop this bureaucratic overreach."

Republicans, as well as farmers and other groups, say the plan could endanger private property rights by giving the EPA a say over temporary waterways like seasonal streams, under the Clean Water Act. Critics warn this could create more red tape for property owners and businesses if they happen to have even small streams on their land. 

The EPA claims, though, this does not expand its authority, and only clarifies it. 

"Let's set aside fact from fiction," Sen. Barbara Boxer, D-Calif., said at the hearing. She rejected the notion that the regulation might allow the government to claim jurisdiction over miniscule water bodies. 

"Puddles, swimming pools, stock ponds are not regulated," she stressed.