Small Foothills and Valley Dry Gulch
Provisional State Rank
* (see reason below)
State Rank Reason
These "stream" ecosystems are abundant across the dry intermountain ranges of Western North America and are usually under private, BLM or National Forest Service land ownership and management.
These are short (<5 miles) dry gulchs, coulees or draws appearing on the 1:100K National Hydrography Dataset layer as 1st order tributaries, generally occurring on south facing hillsides, and rarely to never having intermittent or permanent water. Therefore, they do not typically contain an aquatic community, but may have a robust riparian community. These are typically feeder gullies to a C001 or D001 system type.
The characteristics of the dry gulch ecological system is a lack of water and no aquatic biological communities.
In Montana, the dry gulch type is reported from over 100 sites within the foothills and valleys of the Middle Rockies, including the isolated ranges. These include dry microclimate regions in many of Montana’s mountain ranges, including the south facing slopes of the Elkhorns, Big Belts, Little Belts, Crazys, Gallatin-Madison-Bridgers, Anaconda-Pintlers, Pioneers, Pryors, Bear Paws, Judiths and the Big Snowy Mountains. These ecosystems often fall within the boundaries of BLM, Forest Service or private lands.
Heavy rainfall or summer thunderstorm events may cause these gulchs to temporarily contain and channel water downstream, but flow will not persist for long enough to allow an aquatic community to colonize and become established. Severe storms (i.e., "gully washers") may cause significant erosion of channel bed materials sending them downstream to perennial streams.
Cattle intrusions into the riparian areas along these gullies can cause bank erosion, leading to increased sediment and silt loads being delivered downstream during storms.