Flood — Okanogan, Washington

2018-05-05 to 2018-05-27 · near Oroville, Okanogan, Washington

Event narrative

The USGS River Gage on the Okanogan River at Tonasket recorded a rise above the Flood Stage of 15.0 feet at 4:45 AM PST on May 5th. The river continued to rise, passing through the Moderate Flood Stage of 17.0 Feet at 11:45 PM on May 7th and through the Major Flood Stage of 18.0 feet at 9:15 AM on May 9th. The river crested twice, the first and highest crest of 19.7 feet at 4:30 PM PST on May 11th and the second crest of 19.3 feet at 10:30 AM on May 18th. The river then receded, passing below Major Flood Stage at 9:30 PM on May 20th and below the Moderate Flood Stage at noon PST on May 22nd. The river continued to slowly recede finally passing below the Flood Stage at 2:30 AM on May 27th.

Wider weather episode

Spring time mountain snow melt of heavy snow pack in the Canadian Rockies and the north Cascades brought major flooding to the Okanogan River from Oroville to it's mouth at the Columbia River. Numerous homes and businesses along and near the river suffered basement and first floor flooding in addition to massive inundation of crop lands and orchards in the river valley, with associated irrigation and farming support infrastructure damage and loss.

County and state officials mobilized emergency response crews to shore up levees protecting towns along the river and filled and placed over 200,000 sandbags. Many of the towns along the river were protected by levees, and while there were no major levee failures, minor flooding of homes and buildings behind these dikes did occur through seepage and a few minor breaches. Most of the flooding of homes occurred near the river between the towns.

Okanogan County was included in a State of Emergency Declaration issued by the Washington State Governor for this flooding event.

View location on OpenStreetMap → (48.9436, -119.5173)

Source: NOAA Storm Events Database, event_id 756475. Narrative written by the NWS forecast office that issued the report.