(TNS) -- The Environmental Protection Agency is under fire again over the Clean Water Act rule — this time for using what a federal watchdog called "propaganda" to push the controversial rule.

In a report released this week, the U.S. Government Accountability Office said the EPA violated federal law when it sent out messages through social media regarding the Clean Water Act rule. The rule, which went into effect in August in most states, is controversial.

The congressional watchdog's 26-page report, published Monday, said the EPA's use of an online social media platform called Thunderclap "constitutes covert propaganda" and violates a prohibition on publicity or propaganda by a federal agency.

The Government Accountability Office, a nonpartisan group that works for Congress, stated in its report that the EPA reached 1.8 million users through the innovative platform Thunderclap. The EPA said it sent out the message through Thunderclap to clarify issues surrounding the rule and correct misinformation.

But according to the report, the EPA failed to disclose it was the source of the information in the Thunderclap message.

In an emailed statement to the Standard, the EPA Washington D.C. office said the agency disagrees with the report. The statement said EPA uses social media "just like all other organizations to stay connected and inform people." The agency said its social media activity directed the recipient to a general webpage about the Clean Water Act rule.

But the congressional watchdog said the EPA presented a message designed to be shared by others that supports EPA's efforts, refers to the EPA in the third person, and concealed the fact that EPA crafted the message.

The GAO also said EPA should report the violation to President Obama, Congress and to the Comptroller General because “the agency’s appropriations were not available for these prohibited purposes.”

EPA will have to determine the cost associated with its message sent out through Thunderclap. This may be difficult to do as the work was done internally by staff and individual work hours spent on a specific social media platform or project are not tracked, according to the report.

The Clean Water Act rule, designed to clarify what waterways the federal government has jurisdiction over and can protect, has been under siege since it went into effect in August. Montana and 12 other states sought an injunction against the rule. A North Dakota chief district judge granted the injunction just as the rule was scheduled to go into effect. Because of the injunction, Montana and the other 12 states do not follow the Clean Water Act rule, even though most other states around the country do.

Opinion on the Clean Water Act rule, which EPA says protects streams and wetlands without regulating ground water or stepping on private property rights, divides mostly along partisan lines in Montana. The Montana Mining Association, based out of Whitehall, opposes the rule, calling it federal overreach. Montana Trout Unlimited, based out of Missoula, calls the rule beneficial.

Republican Attorney General Tim Fox has led the charge against the rule in Montana. In an emailed statement to the Standard, Fox stated concern that EPA broke the law and said he would continue to fight to keep the rule from regulating waterways in the state.

Republican U.S. Rep. Ryan Zinke said in an email message that he has "always been critical of the Obama administration's EPA strategy" and vowed to continue to support legislation to keep the agency — established to protect human health and the environment — in check.

U.S. Sen. Steve Daines, also a Republican, said the GAO report “brings into serious question the legitimacy of the agency’s rule-making process.”

Thunderclap was not the sole platform the EPA utilized to reach the public with social media messages about the rule. The agency also used more recognizable platforms such as Facebook, Twitter, and YouTube. The GAO did not find that EPA broke laws through its use of those media forms.

John Wonderlich, policy director for the Sunlight Foundation, a Washington D.C.-based nonpartisan nonprofit organization dedicated to governmental transparency and accountability, said the EPA "probably crossed a line" through its use of Thunderclap.

But, he added, this is really a story on the nature of the tools.

"This isn't a massive coordinated push," Wonderlich said. "It was just an agency staffer who went too far."

The congressional watchdog also looked closely at two other social media campaigns the EPA engaged in. One involved using a hashtag — a popular device on Twitter to track topical conversations — that was labeled the #DitchTheMyth campaign. The other hashtag campaign was called #CleanWaterRules. Neither of those two campaigns violated any regulations, the report stated.

Democratic Sen. Jon Tester, who has long been a supporter of the EPA, said it’s critical the EPA implement the controversial rule correctly.

“Clean water is too vital to Montana’s economy and to the health of our communities to get this wrong.”

©2015 The Montana Standard (Butte, Mont.) Distributed by Tribune Content Agency, LLC.