McALLEN, Texas—The U.S.-Mexico border fence will make life harder on some South Texas farmers, damage valuable wildlife habitat, impair views and generally become an obstacle to border life, the Department of Homeland Security acknowledged in an environmental study of the fence’s impact.

For the people of the Rio Grande Valley, the federal government said in the recent study that there are serious tradeoffs for 70 miles of fence segments that will help Border Patrol control illegal immigration and smuggling from Mexico. But it added that residents will benefit from increased security against “illegal cross-border activity.”

Construction could begin in the Valley next week.

“If you live within a mile or so of the river, which is where the fence will be built, you are eternally sentenced to an unsafe existence,” Eagle Pass Mayor Chad Foster, head of the anti-fence Texas Border Coalition, said in a prepared statement.

However, some South Texas denizens will get a break—the fence will include hundreds of holes so the endangered ocelot and jaguarundi can get to the Rio Grande to drink. And if an animal falls in the hole during fence construction? DHS will provide escape ramps, the plan said.

The department’s Environmental Stewardship Plan for the Rio Grande Valley was controversial before it was ever released. DHS drew up the plan after Secretary Michael Chertoff waived environmental studies required by federal law to speed construction of the fence.

Federal officials said the plans show Chertoff is keeping his promise to be a good steward of the land in the fence’s path.

“The Secretary made it clear when he invoked the waiver authority that that by no means meant we would act without some responsible plan,” Customs and Border Protection spokesman Barry Morrissey said. “The environmental work is still being done.”

New maps of the 21 fence segments running through the lower Rio Grande Valley showed very little variation from preliminary maps released last fall. In Brownsville, the fence will run along the Rio Grande on part of the University of Texas at Brownsville’s campus, but the school’s golf course and undeveloped acreage that the fast-growing school planned to use for expansion will still be behind the fence.

About 14 miles of fence between Roma and Los Ebanos will be built in the floodplain as a “removable” fence. Treaties with Mexico strictly regulate the building of permanent obstacles in the floodplain that could steer floodwaters toward one side or the other.

Morrissey described those segments as similar to concrete jersey barriers commonly seen in highway construction projects, topped with about 15 feet of steel mesh fencing.

“It’s very solid, but it’s portable,” Morrissey said.

The new plan does not clarify the issue of access gates in the fence—one of the most frustrating for landowners along the border who wonder how the gates will be operated, if they will be manned and how access could be restricted.

The question is critical for homeowners whose homes and businesses will be left in the no man’s land between the fence and the river.

Without offering details, the plan recognized that the fence will be an obstacle to farmers in terms of access to the land for themselves and their machinery and livestock, and will increase their costs and possibly decrease the land’s value.

Government contractors will clear about 508 acres of land in the lower Valley. Despite the access holes for the endangered cats, the plan acknowledges that the fence “will likely impact wildlife movement, access to traditional water sources, and potential for gene flow” because some of the species cross the border into Mexico to mate.

Seven segments in Hidalgo County where DHS will build a 15 to 18-foot concrete wall into the river side of levees will not include the wildlife holes. The longest of those segments will be just over four miles, so animals trying to reach the river could move between them, the plan said.