DENVER – Congressional Republicans are questioning whether the Environmental Protection Agency interfered with a separate investigation into the Gold King Mine spill after an earlier internal review clashed with other accounts of the incident.

In a letter Friday to EPA Inspector General Arthur Elkins Jr., U.S. Rep. Rob Bishop, R-Utah, chairman of the House Committee on Natural Resources, and U.S. Rep. Louie Gohmert, R-Texas, chairman of the Oversight and Investigations Subcommittee, questioned the timing and substance of recent interviews conducted by EPA officials.

The separate report from the inspector general is not expected until early 2016.

“It was a very narrow focus, and it was incomplete, and there are obvious discrepancies ...” Bishop told The Durango Herald at a congressional hearing last week at a mine in Idaho Springs, referencing the EPA’s Aug. 24 internal report. “It raises all sorts of questions about what’s taken place. That’s why we’ve got to start over.”

The EPA on Dec. 8 released additional details into its internal investigation, further adding to discrepancies between the agency’s account of the incident and how state officials say it unfolded. The supplemental narrative follows an October Interior Department review of the incident, as well as concerns expressed by the U.S. Army Corps of Engineers regarding the scope of the EPA’s internal investigation.

The EPA has acknowledged fault in the Aug. 5 incident, in which an estimated 3 million gallons of mining sludge poured into the Animas River. The river tested for initial spikes in heavy metals, including lead and arsenic.

State officials, in a September letter, contradicted the EPA’s account of the incident. Mike King, executive director of the Colorado Department of Natural Resources, was clear that the Colorado Division of Reclamation, Mining and Safety “did not have any authority to manage, assess, or approve any work at the Gold King Mine.”

The EPA has maintained since its August internal investigation that the state was on board with a plan to send drainage piping through the entrance of the mine, despite King stating that “operations at Gold King were entirely under EPA management.”

Adding to the controversy, Republicans are fearful that the additional EPA documents served only to “obfuscate efforts to understand the events leading up to the blowout.” They question why the EPA would have conducted follow-up interviews with people “closely associated” with the spill given the inspector general’s ongoing separate investigation and the EPA’s “commitment to ensuring the integrity of witness testimony.”

“As you know, the EPA’s own guidance states that ‘managers should not question staff about their interactions with the OIG,’” Bishop and Gohmert wrote, questioning “best investigative practices” and a possible interference with the inspector general’s work.

U.S. Rep. Scott Tipton, R-Cortez, shares those concerns.

“Given the contradictions in the federal government’s investigations into the Gold King Mine spill, and concerns of potential interference by the EPA in the OIG’s investigation, an investigation wholly independent of the Department of Interior and EPA is appropriate and necessary to get answers,” Tipton said.

An EPA spokeswoman on Monday defended the agency’s internal review, as well as its supplemental narrative.

“EPA and external entities continue to thoroughly investigate the full facts regarding this incident and the response, and the agency will respond based on that information,” the spokeswoman said. “The goal of the addendum was to clarify any points that were not fully examined in either EPA’s internal report or in the DOI report.”

pmarcus@durangoherald.com