The United States Geological Survey (USGS) has identified Mount Rainier as one of the most dangerous volcanoes in the world, and Pierce County is taking steps to improve the warning system to keep residents safe.

Lahars (volcanic mudflows), are the primary hazard during eruptions of Mount Rainier. They are formed by the melting of snow and ice during eruptions and from large landslides.

Pierce County Department of Emergency Management (PCDEM), in partnership with the USGS, has completed the first phase of a multi-phase plan to upgrade and expand equipment for the Mount Rainier Lahar Warning System (LWS). The current system is functioning well, but these improvements will enable PCDEM, USGS, and other partners to provide better and timelier life-safety information to the people that live, work, and play in the areas around Mount Rainier.

The LWS is part of an overall emergency communications system for Pierce County. The focus of the system is to detect volcanic and seismic activity on Mount Rainier and warn residents in the Puyallup and Carbon river drainages of the need to evacuate due to a lahar or other related volcanic activity.

After the 2014 State Route 530 Landslide in Snohomish County, Pierce County Executive Pat McCarthy asked for a risk and readiness review of the LWS to ensure it provides as much warning as possible to the residents of the river valleys fed by Mount Rainier. The planned updates to the instrumentation will provide technological upgrades to the detection monitors close to Mount Rainier. These monitors detect debris flows and provide advanced warning to residents downstream.

Executive McCarthy praised members of the Washington State Congressional Delegation for their efforts to raise awareness of the danger that a Mount Rainier lahar presents and to advocate for additional resources to create a more effective and robust system. “Senators Murray and Cantwell and Congressman Kilmer have been instrumental in advocating for funding of the needed upgrades,” said McCarthy. “On behalf of the over 830,000 residents of Pierce County and the nearly 3 million people that live in close proximity to what USGS has categorized as the most dangerous volcano in North America, I want to express a heartfelt thank you.”

It is anticipated that USGS and PCDEM will continue working on the next phase of the upgrades in 2017.

Mount Rainier has produced multiple lahars that traveled down the river valleys to the Puget Sound lowland. If this were to happen today, the communities in the river valleys, such as Orting, Sumner, Puyallup and Fife, could be completely destroyed, with loss of life in the tens of thousands. Interstate Highway 5 and the Port of Tacoma could also be out of service for an indefinite time with significant impact to the financial health of the Puget Sound Region.

In the early 1990s, USGS, in partnership with Pierce County, established the pilot project lahar early warning system in the Carbon and Puyallup River valleys. This system currently has five lahar sensors in each valley which are connected to 27 warning sirens around the larger communities downstream. Although the larger communities have sirens for early warning of a lahar, many other communities and popular gathering areas in the lahar hazard area do not have any sirens.

  – Pierce County