Priest Rapids Dam Right Embankment Improvements

Project Summary

After years of planning and additional years of dedication, challenging scope, and inspiring teamwork, all major construction at the Priest Rapids Dam was completed in September 2023. The Priest Rapids Right Embankment Improvement project replaced the existing earthen dam, added reinforcement to the right bank of the river to address the stability of the embankment near the Priest Rapids Dam facility, ensuring the safety of the neighboring Wanapum Indian tribal village below, and improving earthquake safety.

A new roller compacted concrete (RCC) dam with a short connecting embankment and secant pile cut-off wall was tied into the existing embankment. The RCC dam was constructed on basalt bedrock downstream from the existing embankment. 



Mattawa, Washington


Grant County PUD No. 2

Contract Amount

$60 million


2021 - 2023

Project Highlights

The IMCO project team monitored for potential dam failures 24-hours a day, seven-days a week while excavating behind the existing embankment.