To ensure U.S. Army Corps of Engineers dams do not present unacceptable risks to the public, the Corps developed and is implementing a risk-based process to prioritize dam safety deficiencies on a nationwide basis. As part of this process, Corps dams are being screened and assigned a safety classification rating. 

   The new dam safety classification system spotlights dams and navigation locks with compelling problems first, so a national priority can be assigned for funding, studies, investigations and remedial work.
   The Corps screening system classified Dworshak Dam as Dam Safety Action Classification-2 (DSAC-2).

   The DSAC rating system includes five categories, with DSAC-5 being the “most safe,” and describes a policy for developing and implementing interim risk reduction measures to reduce the probability of unacceptable performance of Corps dams.
   Dworshak Dam presents no immediate danger to people and property below the dam. While inspections and studies show that seepage and leakage water is passing through the dam’s foundation and/or joint drains, the probability of failure at Dworshak Dam is relatively low.
   Dworshak Dam, like any dam, has maintenance challenges. To address these challenges, the Walla Walla District conducts routine and periodic inspections, monitoring and evaluations to ensure public safety. In the short term, the Walla Walla District is taking the following actions to minimize the probability and risk to the public:

1. Update the Emergency Action Plan (EAP) to include updating notification callout lists, modes of failure, and inundation maps (on-going).

2. Exercise the Emergency Action Plan (EAP).

3. Assess the existing Dworshak Dam communication systems.

4. Perform a potential failure mode analysis.

5. Complete the probable maximum flood reevaluation (on-going).

6. Perform structural anaylses to include an external stability analysis, finite element analysis, trunnion friction analysis for spillway gates, and verification of compliance with the Hydraulic Steel Structures Program (on-going).

7. Improve seepage-water containment to include drain cleaning and reparing failed waterstops (on-going).

8. Update the monitoring program to include modifying the existing instrumentation system, repairing and upgrading instrumentation, and reevaluating monitoring frequency.

   Throughout this process, the Walla Walla District is pursuing long-term, permanent solutions that will help ensure the public remains safe.

   To help keep the public informed, Walla Walla District staff held briefings on Feb. 20 in Clarkston, Washington, and at Dworshak Dam in Ahsahka, Idaho, for state and local emergency managers, elected officials and news media representatives. Walla Walla District will continue to keep the public informed of safety issues related to Dworshak and of the progress made in implementing the interim risk reduction measures.
   To learn more about IRRM actions at Dworshak Dam, check out the links in the above box. 

This web site has been established to provide information the public needs to stay informed. This page may change from time to time as we add more information to keep the public aware of new developments.  Analyses and reports are still under consideration. They will appear here when approved for public release.

Stay informed and involved!!

The POC for this page is: Public Affairs, 509-527-7020

U.S. Army Corps of Engineers, Walla Walla District