Contractors are installing a 17-mile stretch of cylindrical buoys in the river to prevent illegal crossings from Mexico. These are the first of 536 miles of buoys that the federal government plans to stretch from the Gulf of Mexico deep into South Texas. The Department of Homeland Security has waived environmental laws and issued more than $1 billion in contracts to private companies to install them in continuous chains. Each industrial-style buoy is more than 12 feet long and four to five feet in diameter.

Experts consulted by Inside Climate News said they knew of no comparable undertaking on a dynamic river anywhere in the world. They warned that the buoys could speed up flood water in a region that already struggles with flooding. The buoys could also accumulate sediment and create new landforms in the river, provoking treaty disputes with neighboring Mexico. The buoys are planned through Cameron, Hidalgo, Starr, Zapata, Webb, Maverick and Val Verde counties.