The Border Fence with Mexico: What's the Rush?

Late last week, Homeland Security Secretary Michael Chertoff waived more than 30 environmental laws to complete the fence on the Mexican border before the end of this year. About 300 miles have been completed, with 370 left to go. The Clean Water and Endangered Species Acts are among those that won't apply for 361 miles along the Texas-Arizona border. Significant parts of several wildlife refuges will be on the Mexico side.  Private lands will be subject to eminent domain. The Mayor of Eagle Pass, Texas says it's a waste of money that conveys a false sense of security. Why is the government moving so fast? Will better enforcement be enough to justify long-term environmental costs?