The cities of Laredo, Eagle Pass, and Del Rio are the major metropolitan areas and are also ports of entry to Mexico. Possible concerns are nitrogen and phosphorus. Due to elevated levels of fecal coliform bacteria, contact recreation use is not supported. San Felipe Springs are the third largest in the state and supply the drinking water for the city of Del Rio. Concerns identified are for chlorides, nitrogen, and phosphorus.
Rangeland is the predominant land use, but oil and natural gas are also produced in the area.
A concern is identified for total dissolved solids. Phosphorus is identified as a possible concern. The terrain of this area ranges from flat to rolling plains in the upper basin to rough mountainous canyons to the south as the river enters International Amistad Reservoir. The only concern identified is for nitrogen. The Pecos River flows through rough mountainous canyons before entering International Amistad Reservoir.