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US 101 Elwha River Bridge Replacement Project – Environmental Assessment – Fish, wildlife and vegetation

Federally threatened fish species under the Endangered Species Act (ESA) in the Elwha River include the Puget Sound Chinook, Puget Sound steelhead, eulachon, and bull trout. Also, Puget Sound chinook, coho, and pink salmon are federally listed species under the Magnuson-Stevens Fishery Conservation and Management Act (MSA). In addition to these anadromous species, the Elwha River harbors many other species of fish (e.g., sculpins, resident cutthroat).

The project will implement numerous specific avoidance and minimization measures pertaining to fish species. These include best management practices (BMPs) to reduce the risk of delivering sediment to waterbodies, BMP’s to reduce the risk of introducing pollutants to waterbodies, and BMP’s for in-channel construction (i.e. restricting work to approved “in-water work windows”).

Aerial of US 101 Elwha River Bridge with engineered log jam
Conceptual Engineered Log Jam Placement

To mitigate for in-stream impacts the project will install engineered log jams to improve habitat for aquatic species and improve river dynamics by minimizing erosion and potential for unscheduled bridge maintenance.  A preliminary layout of engineered log jam arrays both upstream and downstream of the highway crossing has been identified and will proceed to final design and permitting for inclusion in bridge construction. 

Wildlife habitat effected by temporary construction impacts would be restored through native tree and shrub plantings as described in the Vegetation section of this chapter. Portions of the vacated roadway would be similarly restored.

The project would remove vegetation within the WSDOT right-of-way, riparian area, and on Elwha Project Lands.  Temporary impact areas would be restored with native trees and shrubs appropriate for specific region and conditions of the site. WSDOT will also replant vegetation in collaboration with the National Park Service, who will be responsible for maintaining the property.  The vacated US 101 roadway would similarly be restored where project elements such as the realigned turnoff for the Olympic Hot Springs Road or stormwater treatment facilities are not designated.

For More Information

To read more about vegetation please see Section 3.4.2 (PDF 1.7MB), fish see Section 3.4.5 (PDF 1.7MB), wildlife and wildlife habitat see Section 3.4.6 (PDF 1.7MB), and threatened and endangered species see Section 3.4.7 (PDF 1.7MB).