By Chris Adam

Leaders from more than half the states in the country have now weighed in on lawsuits that seek to halt a recent federal clean water rule.

The latest of the suits against the U.S. Environmental Protection Agency and the U.S. Army Corps of Engineers was filed last week by the attorney general of Oklahoma, Scott Pruitt, who said that the rule will make farm, industrial and private property owners "subject to the unpredictable, unsound, and often Byzantine regulatory regime of the EPA."

And it brought to at least 28 states or their top officials _ spread across five lawsuits _ that seek to derail what was initially known as the "Waters of the United States" rule, which is intended to strengthen and clarify the Clean Water Act by better determining which bodies of water fall under its control.

The rule has been controversial from the start, and congressional Republicans, farmers, developers and other business interests have called it a massive overreach by federal regulators. After it was finalized in May and formally published in June, states began to pounce, filing the raft of lawsuits that aim to stop it.

As Kansas Attorney General Derek Schmidt said in announcing the lawsuit he joined: "Congress never intended for the federal government to regulate ditches or farm ponds. This regulation grossly exceeds the authority granted to federal agencies by the Clean Water Act _ authority that rightfully belongs to the states and that is limited by private property rights protected by the Constitution."

The lawsuits aren't a surprise. Even before the water rule was finalized, experts on both sides of the issue expected it to eventually land in court, where it would become one of many challenges to EPA authority over the nation's land, air and water.

EPA spokeswoman Monica Lee, while not commenting on the specifics of the lawsuits, said in a statement that the rule was necessary because "protection for many of the nation's streams and wetlands had been confusing, complex and time-consuming," stemming from U.S. Supreme Court cases in the 2000s.

The rule was finalized after the agencies held more than 400 meetings and reviewed more than 1 million public comments. The rule, which is set to formally go into effect in late August, will ensure that covered waters are "more precisely defined, more predictably determined, and easier for businesses and industry to understand," she said.

The lawsuits seeking to derail the rule generally contend that the agencies overstepped their authority by violating the Administrative Procedure Act, which limits the scope of rulemaking by federal agencies; by violating the Constitution's Commerce Clause, which gives power to Congress to regulate commerce; and by usurping state sovereignty by limiting how the different state governments can use water on behalf of their citizens.

The rule was proposed by the agencies to simplify and clarify the meaning of the 1972 Clean Water Act. That law covers rivers, lakes and year-round wetlands. But it was less clear about how to handle certain streams that dry up part of the year _ or wetlands that are only wet during springtime months.

The Clean Water Act requires permits for developing or discharging into covered waters, making the rule of vital importance to farmers and other landowners.

Environmental groups have both stressed the fact that the EPA is on strong legal footing with its ruling and that it won't be nearly the massive increase in federal jurisdiction that opponents say.

"We are still reviewing all of the materials and the claims made so far, but are confident that allegations that the rule is more protective than the law allows will not prevail," said Jon Devine, senior attorney with the water program at the advocacy organization Natural Resources Defense Council.

The EPA has said that a very small number of additional waters will be found jurisdictional compared with current practice. Opponents of the rule have called the EPA's estimates laughably small. But until the rule is put into practice in coming years it'll be hard to precisely know what the actual increase is.

Because of the uncertainty in how _ and how quickly _ courts may act, groups opposing the rule are simultaneously pushing for Congress to resolve the issue; Republican-led bills in the works would prevent the EPA from moving forward on the rule.

"Litigation is very expensive and time-consuming _ it could take years for this case to get to the Supreme Court," said Danielle Quist, senior counsel for public policy at the American Farm Bureau Federation, one of the groups that has filed its own lawsuit to stop the rule. "We do believe that Congress needs to act. Litigation is not our preferred option. . . . All the while this rule is in litigation, farmers and ranchers will face a lot of uncertainty and be limited in how they farm their land."

Who Is Suing, and Where?

Lawsuits filed by states, their attorneys general, or executive agencies: _ U.S. District Court for the Southern District of Georgia: Georgia, West Virginia, Alabama, Florida, Kansas, Kentucky, South Carolina, Utah, Wisconsin

_ U.S. District Court for the District of North Dakota: North Dakota, Alaska, Arizona, Arkansas, Colorado, Idaho, Missouri, Montana, Nebraska, Nevada, South Dakota, Wyoming, New Mexico

_ U.S. District Court for the Northern District of Oklahoma: Oklahoma

_ U.S. District Court for the Southern District of Ohio: Ohio, Michigan

_ U.S. District Court for the Southern District of Texas: Texas, Louisiana, Mississippi