News Release

Mount Rainier National Park Announces Environmental Assessment Review and Comment Opportunity for Lahar Detection and Seismic Monitoring System

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Date: May 27, 2021
Contact: Teri Tucker, 360-569-6507

The National Park Service (NPS) has released an Environmental Assessment (EA) for the Lahar Detection and Seismic Monitoring System at Mount Rainier for public review. The EA is available for review and comment through June 25, 2021 at the NPS Planning, Environment, and Public Comment (PEPC) website.

A virtual public meeting for those interested in learning more about the monitoring system is scheduled for Wednesday, June 9 from 4:30 pm to 5:30 pm Pacific time. There will be a short presentation on the monitoring system at 4:30 pm, and park staff will be available to answer questions. The virtual meeting can be accessed through the project website. 

Mount Rainier is an active volcano located within Mount Rainier National Park near the growing Seattle-Tacoma metropolitan area. The mountain poses significant volcanic, landslide, and flooding hazards to park visitors, NPS employees, and neighboring communities. Lahars, or volcanic mudflows, are the primary volcanic hazard with the potential to impact people living, working, or recreating within or near the Mount Rainier National Park. Expansion of the Lahar Detection System would improve overall volcano monitoring and lahar detection capacity and provide more rapid notification to the immediate area and surrounding communities in the event of a volcanic event or mudflow.

The EA was prepared to address a new permit request from the United States Geological Survey (USGS) Cascades Volcano Observatory to increase the existing seismic monitoring system inside Mount Rainier National Park as part of a broader effort to implement a Lahar Detection System for Mount Rainier.

The EA evaluates four alternatives: Alternative 1 – the USGS Proposed Action, Alternative 2 – No Action, Alternative 3 – Alternative Monitoring Sites, and Alternative 4 – Reduced Number of Monitoring Sites (NPS Preferred Alternative). Alternative 1 would add 12 new monitoring stations within the park. Alternative 2 would not add any new stations, and monitoring of volcanic activity at Mount Rainier National Park would continue to be conducted at existing monitoring stations. Like Alternative 1, Alternative 3 would add 12 new lahar detection stations; however, Alternative 3 modifies the USGS Proposed Action for the purpose of avoiding most adverse effects on structures and areas within the Mount Rainier National Historic Landmark District. Under Alternative 4, only nine of the proposed 12 monitoring stations would be approved. Alternative 4 is similar to Alternative 1 – USGS Proposed Action; however, Alternative 4 was developed to reduce the number of stations as originally proposed by the USGS. Alternative 4 would reduce adverse effects on historic structures and minimize the number of new installations within designated wilderness while providing for improved lahar detection as proposed by the USGS. 

For more information on Mount Rainier National Park, please visit To learn more about the Lahar Monitoring and Seismic Detection System please visit the project website.

About the National Park Service: More than 20,000 National Park Service employees care for America's 423 national parks and work with communities across the nation to help preserve local history and create close-to-home recreational opportunities.

Last updated: May 27, 2021

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