The goal of the USGS Lahar Detection System proposal is to mitigate human risk by reducing the amount of time it takes for an alert to be sent out to potentially affected populations and communities after a lahar has been generated. The proposal would also increase the number of total drainage areas covered by the alert system to include the Tahoma Creek and the Nisqually River drainages, which along with the Puyallup River valley, are vulnerable to future landslide-caused lahars from Mount Rainier.
The expanded monitoring system would also improve detection capabilities for smaller debris flow events, particularly along Tahoma Creek which has experienced multiple debris flows since the late 1980s. Five of the proposed monitoring sites were approved and installed in 2020 within developed areas of the park, bringing the total number of existing sites within the park to fifteen.
Of the twelve remaining proposed monitoring sites, several are within the designated boundaries of the Mount Rainier Wilderness. These lands are managed pursuant to the 1964 Wilderness Act, which normally prohibits permanent installations. Sites proposed also include areas within or adjacent to the Mount Rainier National Historic Landmark District (NHLD).
These proposed monitoring and lahar detection sites have been evaluated through an environmental assessment (EA) in compliance with the National Environmental Policy Act to support public engagement and inform agency decision making regarding the USGS proposal.
* indicates the current step in the planning process
Step 1. Evaluate USGS proposal, identify NPS purpose and need, identify planning issues and develop preliminary alternatives
Step 2. Invite tribal consultation
Step 3. Conduct public scoping
Step 4. Refine alternatives and conduct effects analysis
Step 5. Prepare environmental assessment document
Step 6. Public review and comment on environmental assessment (EA)
Step 7. Review public comments and respond to substantive comments
Step 8. Prepare agency decision document
Step 9. Release final plan/decision document to the public *
In late 2019, the US Geological Survey, Cascades Volcano Observatory (USGS) requested a permit to expand the existing volcano monitoring system inside Mount Rainier National Park (MORA). The proposal included 17 new site locations in the park as part of a broader effort to implement a Lahar Detection System for Mount Rainier and to expand the existing volcano monitoring system.