2026 Lahar Evacuation Exercise Information

A lahar is a type of mudflow or debris flow composed of rocky debris and water. The material flows down typically during a volcanic eruption along a river valley. They can also occur during a non-eruption state, also called a no-notice lahar. Lahars are extremely destructive and can destroy any structure in their path. They are also very deep, reaching up to 400 feet in depth.

Lahars can occur by rapid melting of snow and ice during eruptions, by liquefaction of large landslides (also known as debris avalanches), by breakout floods from crater lakes, and by erosion of fresh volcanic ash deposits during heavy rains.

Lahars can range significantly in magnitude. The Osceola Lahar produced by Mt. Rainier over 5,000 years ago resulted in a flow 460 feet deep, which covered an area of 130 square miles. Lahars can also range in speed. Smaller lahars may reach out to a few meters per second. However, larger lahars can reach speeds of over 20 miles per hour. In steep areas, lahars can exceed speeds of 120 miles per hour. 

Due to the town's location between the Carbon and Puyallup rivers, Orting is the most at-risk area if a lahar from Mt. Rainier happens. According to Cascades Volcano Observatory Scientists, a lahar would reach Orting in less than an hour. While the U.S. Geological Survey predicts a lahar from Mt. Rainier event could occur in the next 500 to 1,000 years, we want our students to be prepared and have knowledge in case of an emergency. 

Mt. Rainier, the tallest and arguably most beautiful mountain in Washington, is an active volcano with a high probability of an eruption. The USDS predicts that a lahar event from Mt. Rainier could occur in the next 500 to 1,000 years. If an eruption and lahar were to occur soon, it would put the lives of thousands at risk in Pierce County.

Teaching the next generation of Pierce County residents how to prepare for a lahar is critical. The City of Puyallup has partnered with over a dozen agencies, including school districts, fire police, and public administrations to host the biggest full-scale evacuation exercise in the country.

The purpose of the exercise is to familiarize students with the evacuation routes and to arm them with the tools to be prepared for a real-life evacuation.

The full-scale exercise will occur on Thursday, March 21, 2024, from 9:30 a.m. to 11:30 a.m. During that time, all participating school districts will evacuate their students along their lahar evacuation routes.

The City has partnered with the following agencies to organize this exercise. They are:

• Puyallup School District
• Orting School District
• Sumner-Bonney Lake School District
• White River School District
• Carbonado Historical School District
• City of Puyallup
• City of Orting
• City of Sumner
• City of Bonney Lake
• City of Buckley
• Town of Carbonado
• Town of Wilkeson
• Central Pierce Fire and Rescue
• Orting Valley Fire and Rescue
• East Pierce Fire and Rescue
• Pierce County All Hazards Type III Incident Management Team

The exercise is for students and faculty only. It is meant to educate our students on how to prepare for a lahar. Due to security and safety concerns, only students and their teachers are allowed to walk the evacuation route together.

Although the public is not allowed to participate, they are highly encouraged to educate themselves on lahar preparation tips. For a list of preparation tips, please go to the City of Puyallup's page here.

If possible, OSD recommends that students wear walking or tennis shoes the day of the event, as they are expected to be outside and standing for at least an hour and a half. Also, families are recommended to watch the weather forecast for the day of the exercise, so students can dress accordingly.