Flood — Boundary, Idaho

2012-07-01 to 2012-07-11 · near Porthill, Boundary, Idaho

Event narrative

High flows out of Libby Dam in northwest Montana resulted in widespread flooding along the Kootenai River in and around Bonners Ferry and downstream to the Canadian Border. Flooding along the river began on June 25th and carried over through the beginning of July. Damage occurred along the city dikes in Bonners Ferry. Volunteers had to shore up 500 feet of levy behind the Kootenai River Inn to prevent water from spilling in. Water filled sub-surface storage areas of the General Feed and Grain located near the river in Bonners Ferry. Sloughing of dikes downstream of Bonners Ferry was observed as well. This resulted in an extensive amount of water seepage into farm lands throughout the Kootenai River valley. Over 5,000 acres of farm land was damaged resulting in four million dollars in crop damage.

Wider weather episode

A very wet June and early July, combined with high elevation snow melt, resulted in a record influx of water into Lake Koocanusa since Libby Dam was built in the mid-1970s. Large quantities of water were required to be released out of Libby Dam to accommodate the rising water levels in Lake Koocanusa. Planned dam releases leading up to the event kept the Kootenai River at Bonners Ferry just below flood stage. Added releases from the dam pushed the river above flood levels, which resulted in widespread flooding along the river at Bonners Ferry and downstream to the Canadian border.

View location on OpenStreetMap → (48.9966, -116.4221)

Source: NOAA Storm Events Database, event_id 392958. Narrative written by the NWS forecast office that issued the report.