Debris Flow — Lewis and Clark, Montana

2025-07-31 · near Canyon Ferry, Lewis and Clark, Montana

$11K

Property damage

Event narrative

Jimtown Road and the Riverside Campground was closed due to debris flow from the burn scar flooding. Media also reported a 15 foot debris flow caused by the flooding washed away two trucks and a shed to the shores of Canyon Ferry Lake.

Wider weather episode

An upper-level shortwave combined with monsoon moisture brought a few severe thunderstorms and localized areas of heavy rainfall to North-Central MT. This resulted in isolated large hail, flooding, and a landspout. A stationary storm developed directly over the Great Falls urban area; this produced heavy rainfall and flash flooding in the city, with one gauge reporting 2.25 inches of rain in an hour. Another thunderstorm produced heavy rainfall over the Horse Gulch burn scar, which caused flash flooding downstream.

View location on OpenStreetMap → (46.6033, -111.7392)

Source: NOAA Storm Events Database, event_id 1285061. Narrative written by the NWS forecast office that issued the report.