Extreme rain brings flurry of landslides

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Extreme Precipitation

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Landslide / Avalanche

Prince of Wales Island, Alaska

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Large amounts of precipitation triggered landslides across Prince of Wales Island, blocking roads and damaging at least one bridge.

Observation by Shannon Yates:

Prince of Wales Island in Southeast Alaska had over 50 minor landslide and 6 major traffic stopping landslides from 10.26.2020 and 11.1.2020.

Kelsey Aho, Regional GIS Coordinator with the US Forest Service, writes:

Becki Reynolds, USDA Forest Service Soil Scientist, put together the following brief for the City of Craig:

On the morning of October 26, 2020 the central western coast of Prince of Wales received intense heavy rainfall (about 3 inches in 3 hours) that caused at least 64 landslides on the western coast of the island. Six landslides blocked the Big Salt highway north of Klawock in five locations and 3 deposited sediment and material on the Port St. Nicholas Rd south of Craig. This intense rainfall event appears to have been localized and only within 9 miles of the coastline from Port St. Nicholas north to Staney Creek. It is unclear at this time if there are slides are south of Port St. Nicholas or on any of the outer islands.

Landslides and storm induced debris blocked road access on federal lands. The Shaheen Creek bridge is damaged and the road washed out restricting access to about 23 miles of road past this bridge. Several other federal roads on the western side of the island have damage in the Staney and Steelhead areas. Cumulatively, about 49 miles of federal roads have restricted access due to the October 26th heavy rainfall storm event that caused flooding and landslides. Currently, there are 29 landslides that have been mapped on federal land from this event.

Satellite imagery of the area has been ordered, but cloud cover may prevent image acquisition. The Forest Service will attempt aerial reconnaissance of the area, weather permitting. There were also additional slides reported from the November 1st storm event in the Craig and Klawock area and possible slides on federal lands from the Nov 1st storm.

The Tongass National Forest Facebook page includes a map of known road closures and some pictures of landslides. Please let me know if you need any more additional details or assistance.

Also see that “Resolution 20-18: Natural Disaster Declaration” is on the agenda for today’s (11/5/2020) Craig City Council Meeting.

Comments from LEO Editors:

In the satellite images that LEO accesses, cloud cover obscures Prince of Wales Island.

Over the course of the year, Craig has received more precipitation this year compared to the 1980-2010 average.