Federal officials warned last September that the design of border barriers through Arizona's San Pedro Riparian National Conservation Area would cause environmental damage, according to documents obtained by foes of the fence.
A memo from the Bureau of Land Management, which oversees the site, concludes that putting barriers in the floodway could result in the buildup of debris that would impair the flow of water and change the flow of the San Pedro River, especially during the rainy season.
"The timing and intensity of seasonal flood flows in the San Pedro River are essential for maintaining riparian function as well as recharging the alluvial aquifer," according to the document obtained by the Sierra Club, Defenders of Wildlife and the Center for Biological Diversity. And it warns that, even with promises by the Border Patrol to maintain the fence and clean up debris, it "could inadvertently act as a flood control structure altering natural floor characteristics."
Yet when U.S. Homeland Security Secretary Michael Chertoff decided the following month to proceed with the fence - and exempt its construction from environmental regulations - he concluded the project "would not result in significant impacts to the environment." And Chertoff said that view was shared by BLM.
Sierra Club lobbyist Sandy Bahr conceded this memo and a companion document may be legally meaningless in trying to stop the pedestrian fence and vehicle barriers from being installed: Chertoff's decision to use his power to waive environmental rules means he is free to do what he wants. Still, she called the action "unconscionable."
But Robin Silver of the Center for Biological Diversity said the documents ultimately could help environmental groups win the political battle.
He said once members of Congress see how environmental concerns were ignored in this case they might be willing to rescind the waiver authority they gave Chertoff and his agency in 2005.
And Bahr said the documents could provide legal fodder to remove the fence at some future date if the U.S. Supreme Court sides with the Sierra Club and Defenders of Wildlife and rules that the decision by Congress to give Chertoff that power is unconstitutional.
Either action could pave the way for removal of the barriers - and what Silver believes would be restoration of the river.
The spat centers on a two-mile stretch of the border along the southern edge of the conservation area. A federal judge in October temporarily blocked further work, saying there seemed to be a rush to complete the project with only minimal review.
Rather than wait for the outcome of the case, Chertoff used his power under a 2005 federal law to say the project need not comply with the Endangered Species Act or 19 other federal laws. And the judge threw out subsequent challenges to the validity of that law.