Sixteen states filed lawsuits Monday aimed at blocking the Obama administration’s Waters of the United States rule, which seeks to clarify the bodies of water that the EPA can regulate under the Clean Water Act.

Texas, Louisiana, and Mississippi filed a joint lawsuit in a Houston federal court, asserting that the EPA’s final rule is “an unconstitutional and impermissible expansion of federal power over the states and their citizens and property owners.” While the EPA has the authority to regulate water quality, the suit says Congress has not granted the EPA the power to regulate water and land use.

The lawsuit claims that “the very structure of the Constitution, and therefore liberty itself, is threatened when administrative agencies attempt to assert independent sovereignty and lawmaking authority that is superior to the states, Congress, and the courts.”

In a separate case, Alaska, Arizona, Arkansas, Colorado, Idaho, Missouri, Montana, Nebraska, New Mexico, Nevada, North Dakota, South Dakota, and Wyoming are seeking to have the rule overturned. North Dakota Attorney General Wayne Stenehjem called the rule “unnecessary” and “unlawful,” according to the Associated Press.

According to the Hill, these cases appear to be the first examples of states suing to block the rule, though the rule has faced opposition from states, businesses, farmers, and Republicans since it was first proposed in April 2014.

Finalized in late May, the Waters of the United States rule — commonly referred to as the Clean Water Rule — clarifies what bodies of water the EPA can legally regulate under the Clean Water Act, and restores protections to areas like tributaries and wetlands. The rule extends protections to some two million acres of streams and 20 million acres of wetlands that weren’t clearly protected under the Clean Water Act.

The EPA and environmentalists argue that the rule helps protect the drinking water of millions of Americans, without placing new restrictions or unnecessary burden on agriculture or industry. Some business groups — like a coalition of craft breweries led by NRDC — support the rule, claiming that clean water is central to their operations.

But others — predominantly agricultural interests and Congressional Republicans — have mounted staunch opposition to the rule, painting it as an example of burdensome federal overreach.

Sen. James Inhofe (R-OK), who co-sponsored a Senate bill aimed at forcing the EPA to completely rewrite the rule, has said that farmers in Oklahoma are more concerned about the Clean Water Rule than any other federal policy. The Senate bill, authored by Sen. John Barrasso (R-WY), passed a committee vote and will head to the Senate floor. In May, the House passed a bill sponsored by Rep. Bill Shuster (R-PA) that also sought to block the EPA’s rule.