Senator Barbara Boxer, a California Dem, stirred excitement last Friday when she decried the “huge muzzle” the Obama administration placed on her by deciding not to disclose the whereabouts of more than 40 dumpsites full of coal ash — the often toxic combustion waste from coal-fired power plants.

In its efforts to regulate coal ash, Obama’s Environmental Protection Agency has identified 44 sites that pose a “high hazard” to those who live nearby. The phrase, borrowed from the National Inventory of Dams, means a dyke that could cause death and property damage if it breaks. EPA administrators first hinted at its list of 44 potentially highly dangerous coal-ash sites during a Capitol Hill hearing in April.

But, so far, the agency has refused to release the list. In an “interim” response to a Center request for records under the Freedom of Information Act, the EPA declined to make the list available, stating that “communication with other federal agencies has indicated the rating itself may have national security implications.” According to the agency, the Department of Homeland Security and the U.S. Army Corps of Engineers have advised officials not to disclose the locations of the sites because of terrorism concerns. The EPA also said it’s received “claims from businesses that certain information in the responses should be treated as confidential business information.”

That’s a tough argument to make since the locations of coal-ash dumpsites don’t fit the type of trade secret classified as confidential business information, said Brian Turnbaugh, an environmental policy analyst at OMB Watch. “EPA should be able to release locations of these sites if not specifics,” he said.

Someone at the EPA agrees — at least about the business argument. “I believe there is no justification for a confidential business information claim,” Richard Kinch told Papertrail following inquiries about the agency’s interim FOIA response. He said the agency still has to resolve the claims of roughly 20 utilities before it can officially determine whether or not the 44 sites are entitled to such confidential treatment.

But by far the bigger hurdle has to do with those “national security implications.” On Friday, Boxer, whose Environment and Public Works Committee has held hearings on coal ash threats, sent a letter to the EPA, DHS, and Army Corps asking why they’re treating the coal-ash facilities differently than such hazardous-waste facilities as Superfund sites or chemical plants.

Pointing out the double standard won’t necessarily sway the EPA. Kinch says the Army Corps’ dam inventory database includes 12,000 similar high-hazard dykes across the country — mining dams, power plant dams, coal-ash dams — but none of them are accessible to the public. “Why should we treat the coal-ash sites any differently than the other high hazard dams?” he asked.

Last week, the EPA began notifying local officials and first responders about the 44 sites; sources tell Papertrail they involve 10 states, including Pennsylvania, West Virginia, and Kentucky.