Mount Rainier National Park
State Route 410 White River Flood and Erosion Risk Reduction Proposal
Introduction
Providing sustainable public access to and through Mount Rainier National Park on SR 410 is a shared management goal for the National Park Service (NPS) and the Washington State Department of Transportation.
The Washington State Department of Transportation (WSDOT) proposes to install two engineered log structures to protect a section of State Route 410 between mileposts 58 - 60 that is at high risk due to flooding and erosion from the White River. The proposed project site is outside the existing road prism, within the adjacent Mount Rainier Wilderness.
State Route 410 serves as a gateway to Mount Rainier National Park’s east side, including access to multiple popular trailheads and the White River Campground and Sunrise areas. It is an important transportation corridor connecting with the greater Seattle/Tacoma area to the north and west, and the greater Yakima area to the east. Several miles of SR 410 are located within the boundaries of Mount Rainier National Park.
The intent of the proposed project is to prevent major flood damage to the road segment between mileposts 58-60 in the near-term. Road damage or washout would affect public access to the area, potentially lengthening travel times by up two hours to bypass the damaged section. If damaged, repairs to restore the road corridor may be prolonged, costly, and environmentally consequential, particularly if the White River changes course and begins flowing directly in the existing road corridor.
We Want to Hear From You
The National Park Service (NPS) is evaluating the effects of the WSDOT proposal. Public review and comment will be accepted at several points during this process. This website provides information about the proposed project location, current conditions, key issues that have been identified, other alternatives that have been considered, and information about the planning process and how to participate.
You are invited to provide input from March 12 - April 11, 2025 using the NPS Planning Environment and Public Comment website. This information will help the planning team evaluate the proposed action to support informed decision-making and to meet the requirements of the National Environmental Policy Act, Wilderness Act, National Historic Preservation Act, Endangered Species Act, and other applicable legal requirements.
Submit Comments Here:
Project Location
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Mount Rainier Wilderness
The proposed project is within the Mount Rainier Wilderness at Mount Rainier National Park.
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White River
This section of State Route 410 is directly adjacent to and within the floodplain of the White River. The White River is a glacier-fed river that drains Mount Rainier’s Emmons Glacier, the largest glacier in the continental U.S. outside of Alaska. Several locations along SR 410 have been damaged by past flooding. The road is increasingly at risk from flooding and erosion from the White River that has the potential to damage or wash out key sections of the road.
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State Route 410 (Mather Memorial Parkway)
State Route 410 includes the Mather Memorial Parkway. This 107-mile-long state highway connects the greater Seattle/Tacoma area to eastern Washington, traversing Pierce, King, and Yakima counties. State Route 410 is a major vehicle access route to Mount Rainier National Park.
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The proposed project area is located near State Route 410 between Mile Post (MP) 58 and MP 60 near the north entrance to Mount Rainier National Park. This section of the highway is adjacent to the White River in a forested area of the park.
Current Conditions
These photos show the current conditions at the project location.
Click play, choose from the thumbnails, and pan in the main image for a 3D view of the project location
Recent Flood Events
Flood events occurred in 2003, 2005, 2006 and 2016, and resulted in WSDOT installing emergency riprap bank protection in several of these locations to prevent further damage to the highway. Sections of the highway are still in imminent danger of flooding and bank erosion. New side channels formed in the floodplain during spring 2017 that are aimed toward the roadway. Immediate action is needed because additional flood erosion could result in damage or loss to this section of road.
Question: What information would you like the park to consider in evaluating the Washington State Department of Transportation proposal to reduce flooding and erosion risks?
Past actions in response to flooding and erosion have included placement of riprap and concrete barriers to help protect the road. However, the current risk has the potential to result in greater road damage should the main channel of the White River shift into the existing highway corridor. If this occurs road materials may be deposited within the White River floodplain and the Mount Rainier Wilderness.
Key Issues
The proposed flooding and risk reduction project has the potential for both short- and long-term impacts to the area. This would include short-term impacts during construction from temporary noise disturbance, traffic delays or short-term closures, and long-term impacts from vegetation removal and installation of engineered log structures within the White River floodplain.
Access
Construction is proposed during late summer 2027. Short-term road closures may be required during construction for traffic safety. Traffic delays up to 30 minutes may be required during the approximately three weeks of construction.
No trailheads would be closed by the proposed construction. Some roadside pull-out areas would be used as project staging during construction and would not be available for roadside parking.
If this section of State Route 410 is damaged by the White River travel times would increase up to two hours due to changes in travel routes, for example needing to use State Route 12 and State Route 123 to avoid this section of State Route 410.
It is possible that the White River could permanently realign to occupy sections of the highway prism. This could result in extensive environmental impacts and lengthy road closures before travel could be reintroduced to this section of State Route 410.
Question: How would temporary or long-term closure of this section of State Route 410 affect you? How would it change your travel to or through Mount Rainier National Park and the surrounding area?
Wilderness Area
The Mount Rainier Wilderness was designated as part of the Washington Park Wilderness Act of 1988. The wilderness designation includes 97% of Mount Rainier National Park. Designated wilderness must be managed according to the provisions of the Wilderness Act of 1964.
The proposed flooding and erosion risk reduction project would be located more than 200 feet from the centerline of State Route 410 within designated wilderness.
The proposal includes installations/structures, mechanical transport, and motorized equipment within wilderness. These activities are generally prohibited in wilderness and will be evaluated to determine if the proposed action meets the requirements of the Wilderness Act. Construction access plans are being developed by WSDOT in coordination with the National Park Service.
Learn about about wilderness here:
Floodplains and Wetlands
It is National Park Service policy to preserve floodplain functions and values and minimize potentially hazardous conditions associated with flooding, including threats to human health and safety, risk to park infrastructure, and impacts on natural and beneficial floodplain values.
The National Park Service works to avoid adverse wetland impacts to the extent practicable and minimize impacts that cannot be avoided.
The intent of the proposed installations is to halt further movement of the channel towards the road and would be designed to inhibit large shifts of the river channel that would increase downstream flood risk.
Wildlife and Habitat
The project area is located within suitable habitat for multiple species of fish and wildlife, including several species listed under the Endangered Species Act.
Learn about wildlife at Mount Rainier National Park here:
Northern Spotted Owl
The project area is located within suitable habitat for the Northern Spotted Owl. The proposed construction timing is during the nesting season. Construction activities would result in a temporary increase to noise and activity levels in the project area and have the potential to affect northern spotted owls that may be present in the project area.
Marbled Murrelet
The project area is located within suitable habitat for the marbled murrelet, which is listed as a threatened species. The National Park Service has not detected marbled murrelet in the upper White River watershed during past monitoring efforts and does not expect marbled murrelet to be present in the project area during the nesting season.
Chinook Salmon And Steelhead
Portions of the White River within the project area contain critical habitat and migration paths for several fish species including the Puget Sound steelhead and Puget Sound Chinook salmon which are listed as threatened species under the Endangered Species Act.
The proposed construction of engineered log structures has the potential to affect these species due to short-term impacts to water quality during construction. The long-term effects to aquatic habitat are expected to be less than traditional bank armoring materials.
Bull Trout
The project area also contains spawning and rearing habitat for bull trout which is also a threatened species under the Endangered Species Act.
Construction is proposed during a timeframe that would minimize potential impacts to sensitive fish species using natural materials similar to what is present within the floodplain. The proposed design is intended to avoid the impacts of traditional concrete and rock barriers while providing additional protection from flooding and erosion due to high flows of the White River. Both short- and long-term effects to fish habitat will be analyzed to help inform decision-making.
Preliminary Alternatives
Preliminary alternatives are different ways that the National Park Service and Washington State Department of Transporation have identified to address the flooding and erosion risk from the White River to State Route 410 within Mount Rainier National Park.
No Action
To help evaluate the impacts of the proposed action, the National Park Service will also evaluate the potential effects of not taking action to provide a comparison.
Under this scenario the current proposal from the Washington State Department of Transportation would not be approved and the agencies would continue routine maintenance and operation of the road.
State Route 410 would continue to experience periodic flooding and erosion events that may result in temporary closures during peak flows. Emergency response actions would continue when needed.
If extensive damage occurs long-term closures may be required. The scope of potential environmental impacts and length of potential closures would vary in response to the scale of damage to the road.
Question: What should the National Park Service consider in defining and analyzing the "No Action" alternative to reflect existing conditions and the effects of not proceeding with any construction options?
Proposed Action: Install Two Engineered Log Structures
The Washington State Department of Transportation has proposed installing two engineered log structures along the bank of the White River. The proposed log structures would be designed using natural materials. The engineered log jam would be designed to mimic log jams that are found in many river corridors within densely forested areas.
These structures would be designed to slow the flow of water in key areas and reduce the effects of flooding to limit erosion. The National Park Service is evaluating potential sources for the logs, including areas within the park where downed trees are present. To avoid the impacts of temporary road construction and use of heavy equipment within the floodplain forest and designated wilderness, helicopter use is proposed to transport and place the logs in coordination with people on the ground to complete the proposed installations.
Question: What questions do you have regarding this proposal? What should the park consider in evaluating the potential short- and long-term effects of this action?
Alternatives Considered But Dismissed
The current WSDOT proposal is intended to mitigate the near-term risk to the road in an area where substantial damage is most likely to occur and where the potential for negative impacts to access are greatest.
Other alternatives were identified by the Washington State Department of Transportation and the National Park Service to reduce the risk of flooding and erosion from the White River to State Route 410, including:
- Reconstructing the road on top of an armored causeway.
- Constructing a reinforced or earthen dike using compacted soils to divert water away from banks experiencing erosion.
- Constructing a concrete wall or mechanically stabilized wall.
- Replacing the current road with an elevated road segment on piers or a trestle to allow water to move under the structure.
- Completing extensive tree planting efforts and placement of wood structures to strengthen the existing floodplain forest adjacent to the road corridor.
- Relocating the road to higher ground.
These options were evaluated to determine if they were reasonable and feasible approaches to addressing the near-term risks to this section of State Route 410. Although some of these options may be considered in future long-term planning efforts, the options above were not carried forward for further analysis at this time due to economic infeasibility, inability to meet the need for near-term risk reduction, the ability to meet the need with less environmentally damaging and less expensive alternatives, or the need for a change in law to implement the proposal.
Question: Are there other alternatives that should be considered to address the near-term risk to this section of State Route 410 from flooding and erosion from the White River?
Planning Process
The National Park Service is seeking public comment through April 11, 2025. Your comments will help the planning team evaluate the Washington State Department of Transportation proposal and will help determine next steps in the planning and environmental compliance process to support decision-making.
The project website will be updated as this planning process moves forward including dates and time for virtual public meetings, additional review periods and opportunities to comment.
Thank you for your interest and participation.
Visit the project website here:
How to Comment
Public participation is an important element of the planning process, and we welcome your ideas, concerns, issues, suggestions, and potential topics for consideration.
Submit your comments here no later than April 11, 2025:
Please note that your entire comment, including your personal information, may be made publicly available at any time. Although you can request that we withhold your personal identifying information from public view, we cannot guarantee that we will be able to do so.
