"The DEIS goes to great lengths in an attempt to establish impacts to water resources from uranium mining. It fails to do so, but instead creates enough confusion and obfuscation of hydrogeologic principles to create the illusion that there could be adverse impacts if uranium mining occurred."
Another park service colleague, Bill Jackson, wrote back that Martin's concerns were not a "shock," and in another email said there was no information that contradicted Martin's case.
Bishop, who chairs the House Natural Resources subcommittee over national parks and public lands, said he was concerned Interior officials came to their conclusion against the advice of their own experts.
"It is now increasingly apparent that the decision was motivated by politics rather than science as the administration would have us believe," Bishop said in a statement. "We feared this was the case when the [Interior Department] announced its intentions in January, and it is unfortunate that it has proven to be true."
But congressional testimony backs Interior's findings that uranium mining has already damaged watersheds in the area.
"Scientific evidence suggests that the exploitation of uranium resources near the Grand Canyon will be intimately connected with the groundwater aquifers and springs in the region," testified David Kreamer, professor of geoscience at the University of Nevada in Las Vegas. "The hydrologic impacts have a great potential to be negative to people and biotic systems."
Taylor McKinnon, public lands director for the Center for Biological Diversity, says uranium concentrations in Horn Creek, near an old mine in the Grand Canyon National Park are 10 times federal drinking water standards.
"So the contamination threat isn't speculation, it's reality, and the administration was right to take precautions preventing more of it," McKinnon said.
Interior spokesman Adam Fetcher said the department will review the committee's letter but, in the meantime, defended the January decision to block more mining in the area.
"A withdrawal from new mining is the right decision for this priceless American landscape one that was based on the best available science," Fetcher said. "The withdrawal maintains the pace of hardrock mining, particularly uranium, near the Grand Canyon but also gives us a chance to monitor the impacts associated with uranium mining in this area."
Park Service Director Jonathan Jarvis concurred.
"As stewards of our national parks, it is incumbent on all of us to continue to preserve our treasured landscapes, today and for future generations," Jarvis said.
Bishop on Wednesday requested a slew of documents from the Interior Department related to the decision on uranium mining, including briefing papers, memos, notes and emails.