Sub-locations
| Name | Sites | Samples |
|---|---|---|
| Madison County | 8 | 72 |
| McCone County | 3 | 5 |
| Meagher County | 1 | 5 |
| Missoula County | 2 | 2 |
| Musselshell County | 1 | 4 |
| Park County | 13 | 73 |
| Phillips County | 13 | 72 |
| Powder River County | 15 | 36 |
| Powell County | 1 | 2 |
| Prairie County | 3 | 5 |
| Ravalli County | 1 | 2 |
| Richland County | 1 | 2 |
| Roosevelt County | 1 | 2 |
| Rosebud County | 45 | 261 |
| Sheridan County | 3 | 8 |
| Silver Bow County | 1 | 1 |
| Stillwater County | 1 | 2 |
| Sweet Grass County | 2 | 12 |
| Teton County | 1 | 3 |
| Toole County | 3 | 10 |
| Treasure County | 1 | 2 |
| Valley County | 3 | 10 |
| Wibaux County | 6 | 10 |
| Yellowstone County | 3 | 29 |