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Boise Creek Mitigation Project

Boise Creek Mitigation Project

Mitigation Reserves Program

Project Description  

The Boise Creek Mitigation Project is located on a 4.5-acre portion of the Middle Boise Creek Natural Area on the left bank of Boise Creek downstream from 284th Ave SE. The Boise Creek Mitigation Project will create wetland and aquatic habitat while preserving native riparian buffers. Construction begins in 2024 and the completed project will create 2 acres of new wetland and aquatic area. The Boise Creek Mitigation Project will compensate for unavoidable permitted impacts to wetlands and aquatic resources in Water Resource Inventory Area (WRIA) 10.


Boise Creek is extremely important to the Puyallup/White River Watershed because it provides spawning and rearing habitat for Chinook salmon (spring, fall runs) and steelhead trout. Coho, pink, and chum salmon, and cutthroat trout are also present in Boise Creek. Boise Creek is degraded due to past land use activities and water temperatures in Boise Creek consistently exceed state standards for salmon spawning and incubation. There is a significant lack of woody vegetation, and consequently, shade to the creek.

Boise Creek is identified in the Salmon Habitat Protection and Restoration Strategy for Puyallup and Chambers Watersheds as a high priority tributary for restoration and protection of natural geomorphic processes and riparian function. King County has successfully implemented three salmon restoration projects on Boise Creek downstream of the Boise Creek Mitigation Project. The Boise Creek Mitigation Project will complement these successful projects and add rearing and refuge habitat for salmon further upstream. The project will protect riparian habitat and is expected to improve water quality, while adding needed salmonid habitat on Boise Creek. Wetlands will be established with large wood and diverse native vegetation. The Boise Creek Mitigation Project will provide mitigation credits for King County’s Mitigation Reserves Program.

Vicinity Map


JPEG (1,269 KB)


Aerial imagery of site prior to mitigation project construction:


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Project Design

The Boise Creek Mitigation Project will establish wetland and aquatic features and enhance riparian habitat. Plans include fill removal, installation of large and small habitat wood and native plantings. 

30% Design Plan View:

Boise Creek Mitigation Project 30% Design Plan


Project Schedule

Boise Creek Mitigation Project schedule overview

Alternatives analysis  

August 2022

30% design plans 

December 2022

60% design plans 

June 2023

90% design plans 

September 2023


Summer/Fall 2024


2025 - 2034


Project Documents

coming soon


Point of Contact

Design Project Manager -- Deb Pessoa
Project sponsor / Mitigation Reserves Program Manager -- Megan Webb

For questions about King County's Mitigation Reserves Program, please contact program staff.