Upper Nisqually Channel Migration Protection

About the Project

Pierce County constructed a series of rock deflectors called groins along the upper Nisqually River flood control facility. There are 28 rock deflectors, which are constructed in front of and on top of the lower portion of the existing levee face and are buried as deep or deeper than the existing toe.

The purpose of the deflectors is to reduce and divert erosive flows away from the levee toe to preserve the structure and to reduce overall maintenance costs. The facility is a combination levee and revetment and is positioned along the north bank of the Nisqually River, south of state Route 706 at the Mount Rainier National Park boundary.

 Approximately 4,760 feet of the facility was treated with these deflectors, including approximately 2,135 feet contained within the park and 2,625 feet outside of the park. This levee protects SR 706, a state highway and the main entrance to Mount Rainier National Park. The road had been substantially damaged in 2006 due to a flood event. 

This project was completed in late 2021 with partners from Mount Rainier National Park and Active Construction Inc.