Debris Flow — Custer, Idaho

2025-08-26 · near Stanley, Custer, Idaho

Event narrative

The Idaho Transportation Department closed a 12-mile stretch of state Highway 21, from Banner Summit to Grandjean Road, due to a landslide on on August 26th.

ITD stated on Facebook around 5:30 p.m. Tuesday that the section of highway will be 'potentially' closed for the next two days.

The closure came shortly before the National Weather Service issued a flash flood warning for the Highway 21 corridor south of Banner Summit.

View location on OpenStreetMap → (44.0153, -115.2151)

Source: NOAA Storm Events Database, event_id 1290868. Narrative written by the NWS forecast office that issued the report.