EL PASO, Texas -- Experts say the proposed 700-mile border fence could harm the environment and cut into the tourism industry.

Congress approved a homeland security bill Friday that included $1.2 billion to build a fence along the U.S. Mexico border. The $1.2 billion is a down payment for the fence. No one knows how much it will actually cost.

Republicans say the fence is “a giant step'' in keeping out illegal immigrants.

But environmentalists say the plan could destroy habitats and cut off access to water for numerous creatures, including the already endangered ocelot.

Businesses could be harmed by the fence as well. The vice president of the McAllen Chamber of Commerce's Convention and Visitors Bureau said McAllen is a top shopping destination for Mexican nationals. A fence could slow economic traffic the community has come to rely on.

Texas Sens. Kay Bailey Hutchison and John Cornyn voted for the fence bill, but they failed in their effort to amend it. They wanted to allow border communities to have some input in where fencing will be located and how much of it is erected in their areas.

Hutchison said she received a commitment from the Senate Majority Leader and the Speaker of the House promising to address the concerns when Congress returns from recess.

Congress has abandoned Mexico's top priority: an immigration accord that would have allowed more Mexicans to work legally in the United States. Bush had proposed a temporary worker program that would have given out three-year work visas to those with jobs lined up in the U.S.

Instead, U.S. lawmakers have focused on increasing security along the border. The added security has angered Mexico, which sees the actions as a militarization of the two countries' common frontier.