Spirit Lake Outflow Safety Improvement Project

Current Information

The Draft Environmental Impact Statement (DEIS) is available for review and commenting. Comments due by October 30, 2025. Find the document here: https://www.fs.usda.gov/r06/giffordpinchot/projects/66482
In-Person DEIS meeting to be held October 7, 2025, 4pm-7pm at the Cowlitz County Event Center in Longview, WA.
Sign-up for emails
Frequently Asked Questions: Spirit Lake Outflow FAQ

Following the 1980 eruption of Mount St. Helens, the natural outflow for Spirit Lake was blocked by a debris avalanche. The Spirit Lake outlet tunnel was constructed under emergency conditions to maintain safe lake levels. The tunnel is in an area of volcanic, geologic, hydrologic, and seismic hazards. These hazards increase the potential for breach of the debris blockage and/or tunnel failure, putting downstream communities at risk of a catastrophic mudflow in the event of a full lake breach.

Gifford Pinchot National Forest is conducting stakeholder engagement and environmental analysis to identify a long-term Spirit Lake outflow solution. The lake has the potential to affect tens of thousands of people in the downstream communities within the Toutle, Cowlitz, and Columbia River systems.

Safely managing the water level of Spirit Lake is critical, as nearly 50,000 people live downstream of the tunnel outflow. Identifying a solution that maintains safe water levels of Spirit Lake while addressing the unique resources and values present in the Mount St. Helens area are all part of this unique project.

We will be updating the public with current information as the project evolves. There are key opportunities for stakeholders to engage and get involved along the way. We anticipate environmental analysis scoping in August 2024.

Please join the Spirit Lake Outflow Safety Improvement Project email list to receive updates and learn about upcoming virtual and in-person meeting opportunities.

*Virtual Public Meeting 1: Explore the presentation and meeting recording.

*Virtual Public Meeting 2: Explore the presentation and meeting recording.

*Environmental Analysis (NEPA) In-Person Scoping Meeting: October 23, 2024. 4pm to 8pm.

*Virtual Public Meeting 3: Explore the presentation and the meeting recording.

For more information on the project and scoping process see: Spirit Lake Scoping Handout and the Public Scoping Letter.

What Can Be Done?

Spirit Lake Alternatives

Years of public outreach from various stakeholders ranging from local business owners and homeowners to Tribes, county, state, and federal agencies has led to the development of nine alternatives (potential solutions) for the long-term management of the Spirit Lake Outflow. These nine alternatives are separated into two categories, Primary (P) or Redundant (R) as depicted in the graphics below. To meet the purpose and need for the Project, there must be a primary outflow measure with a redundant outflow measure to create resilience and improve safety. These graphics show the location of each alterative in the project area and depict each alternative and the action that could be taken.

Alternative one is taking no action or changes to the landscape. Alternatives two, three, and four would alter the existing tunnel in some way. Three wrenches are for major tunnel repairs, one wrench represents minor tunnel repairs, and the additional pressure gauge indicates that the existing tunnel would be retrofitted into a pressure tunnel system with major construction. Alternative five is the creation of a brand-new pressurized tunnel adjacent to the existing tunnel. Alternative six would mechanically excavate a large open channel draining the lake to the North Fork Toutle River. Alternative seven would lead to the formation of a natural channel that would drain to the North Fork Toutle River if it were paired with a pressurized tunnel. Alternative eight would install a buried conduit pipe to drain water from Spirit Lake west towards the North Fork Toutle River as needed and Alternative nine would rely on the storage capacity of Spirit Lake.