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. The economy of the area is based on ranching. Concerns identified are for chloride, sulfates, and total dissolved solids.
Possible concerns are nitrogen and phosphorus.
The Devils River is a tributary to International Amistad Reservoir. There are no major population centers in the watershed. The land is used for ranching. Concerns identified are for forms of nitrogen. Total dissolved solids are identified as a possible concern.