| 1 |
Stream 1st-2nd order or <30 miles long | ||
| 1 |
Stream 3rd-5th order or 30 - 100 miles long | ||
| 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) | ||
| 1
|
Yellowstone
River downstream from Billings or the Missouri River downstream from Great
Falls |
||
| 2
|
Perennial
1st or 2nd order stream above 1000m elevation in the Wolf Mountains, Powder
River Basin or Missouri Breaks |
||
| 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 |
||
 |
| Ecoregions are based on Omernik’s Level III Ecoregion delineations
(see Woods, A.J. et al. 2002. Ecoregions of Montana. 2nd edition poster).
The Northwestern Great Plains are the Northwestern Great Plains Level
III Ecoregion (#43). |
