US 97A - Rock Slope Scaling

Project news

This project was completed on Thursday, June 25  A seperate project to address rock slopes at Knapps Hill tunnel began June 15 and is expect to be complete by Friday, July 3.  That section of roadway remains closed between milepost 223- 230, but access between Entiat and Chelan in SR 971 available.

This project was awarded to Strider Construction on Jan. 14, 2020 for $660,265.20.  An open house for this project was held on August 14, 2019 at the Chelan City Hall and the Entiat Grange Hall on August 20.  The purpose of the outreach events was to receive input regarding travelling needs on US 97A, and how different closure times required to complete the work will affect the public.  

Needs & benefits

Slope instability is a category of natural hazard that refers to the movement of a soil or rock mass under the influence of gravity, leading to slides and falling rocks.  Rock falls can occur on both natural and excavated slopes and are caused by a combination of influences, including weather.  WSDOT's unstable slope management program is a proactive infrastructure-preservation program. 

To reduce the risks of the adverse effects of unstable slopes to our highway system in a cost-effective manner, this project will remove loose, unstable rock from slopes adjacent to the US 97A roadway.  The slopes that have been identified for this work have chronic rock fall problems with rocks reaching the highway numerous times a year, which requires maintenance call out and unplanned repairs, as well as represents a significant risk to the travelling public.

The slopes that have been identified for this work are located at the following locations on US 97A:

  • Slope 1: milepost 217.62 to 217.68 between Entiat and the junction of SR 971/Navarre Coulee Road,
  • Slope 2: milepost 219.80 to 219.90 between Entiat and the junction of SR 971/Navarre Coulee Road,
  • Slope 3: milepost 224.09 to 224.13 between the junction of SR 971/Navarre Coulee Road and Knapps Hill Tunnel.


Construction began May 20 and is expected to be complete by the end of June 2020.


This project is funded through the Highway Capital Preservation -Unstable Slopes Program (P3) for the 2020 construction season.


Brian Pearson

US 97A Rock Slopes Vicinity Map