| 1 |
Stream 1st-2nd order or <30 miles long |
|
Go to 2 Below |
| 1 |
Stream 3rd-5th order or 30 - 100 miles long |
|
Great Plains Prairie Stream |
| 1 |
River >5th order or >100 miles long |
|
Medium Prairie River |
| 1 |
River >5th order and >200 river miles long and a direct tributary to the Yellowstone or Missouri River (Little Missouri, Tongue, Bighorn and Powder Rivers) |
|
Large Prairie River |
| 1 |
Yellowstone River downstream from Billings or the Missouri River downstream from Great Falls |
|
Large Valley River |
|
| 2 |
Perennial 1st or 2nd order stream above 1000m elevation in the Wolf Mountains, Powder River Basin or Missouri Breaks |
|
Great Plains Perennial Spring |
| 2 |
Small (< 100m2 in area), low gradient intermittent pools separated by long breaks of dry stream bed, typically lacks downstream connectivity to a large mainstem river |
|
Great Plains Intermittent Stream |
