House Republicans are calling for an investigation into whether the Environmental Protection Agency planned to kill a controversial Alaska copper-and-gold mine from its inception, according to documents obtained by the Washington Examiner.

The EPA last month moved toward issuing a preemptive veto of a key mining permit for the proposed Pebble Mine in Bristol Bay, Alaska. The agency said the mine would destroy salmon runs that are home to nearly half the world's sockeye salmon, and would disrupt the lives of native tribes.

House Oversight and Government Reform Committee Chairman Darrell Issa, R-Calif., urged EPA's internal watchdog to investigate the agency's handling of the Pebble project Friday, saying it had planned to use a preemptive veto to block the mine from the outset.

"EPA's actions regarding the preemptive use of Clean Water Act section 404(c) are unprecedented and appear to rest upon an evaluation written with a predetermined conclusion of invoking a preemptive 404(c) veto of the Pebble Project," said Issa, along with Energy Policy, Health Care and Entitlements Subcommittee Chairman James Lankford, R-Okla., and Economic Growth, Job Creation and Regulatory Affairs Subcommittee Chairman Jim Jordan, R-Ohio, in a letter.

The letter to EPA Inspector General Arthur A. Elkins Jr. cited an internal EPA presentation in January 2010 that listed a preemptive veto of a key mining permit as one of the options available to the agency.

That presentation, however, also listed three other options.

"The agency referenced 404(c) [veto] as one of several outcomes, including the permitting process," EPA spokeswoman Alisha Johnson told the Examiner. "It wasn’t until the scientific assessment was complete that agency leadership was able to make a decision on whether the circumstances warranted moving forward with review under 404(c)." The 404(c) section of the Clean Water Act regulates dredged and fill materials flowing into watersheds.

The letter from Issa referred to another internal EPA document from September 2010 that showed the agency discussing the benefits and drawbacks of issuing a Clean Water Act veto. The agency did not appear set on that action, as the document said, "It’s still possible that a veto will not prove necessary."

Pebble's Republican and industry boosters say a preemptive veto like the one EPA is moving toward would be "unprecedented," as the project's developers have not submitted a formal blueprint.

They say the agency used a "hypothetical" mine to conduct its environmental evaluation — therefore, they say the veto would be preemptive, and that such a step could spook investment near waterways.

The EPA, however, has said it possessed enough information to conduct its environmental tests based on Securities and Exchange Commission filings by Pebble's developers.

CORRECTION: The EPA did not perform an environmental impact statement on the Pebble Mine. This story was updated at 2:09 p.m. on March 17, 2014, to reflect that. The Washington Examiner regrets the error.