Ecoregions
| ID | Realm | Major Habitat Type | Ecoregion |
|---|---|---|---|
| 131 | Nearctic | Xeric freshwaters and endorheic (closed) basins | Gila |
| 132 | Nearctic | Temperate upland rivers | Upper Rio Grande - Bravo |
| 133 | Nearctic | Xeric freshwaters and endorheic (closed) basins | Pecos |
| 134 | Nearctic | Xeric freshwaters and endorheic (closed) basins | Rio Conchos |
| 135 | Nearctic | Temperate floodplain rivers and wetlands | Lower Rio Grande - Bravo |
| 136 | Nearctic | Xeric freshwaters and endorheic (closed) basins | Cuatro Cienegas |
| 137 | Nearctic | Xeric freshwaters and endorheic (closed) basins | Rio Salado |
| 138 | Nearctic | Xeric freshwaters and endorheic (closed) basins | Rio San Juan (Mexico) |
| 139 | Nearctic | Tropical and subtropical coastal rivers | West Texas Gulf |
| 140 | Nearctic | Temperate coastal rivers | East Texas Gulf |
| 141 | Nearctic | Temperate coastal rivers | Sabine - Galveston |
| 142 | Nearctic | Temperate upland rivers | Upper Missouri |
| 143 | Nearctic | Temperate floodplain rivers and wetlands | Middle Missouri |
| 144 | Nearctic | Temperate upland rivers | US Southern Plains |
| 145 | Nearctic | Temperate upland rivers | Ouachita Highlands |