Advance Mitigation Site at Little Bear Creek

Description - Completed

Snohomish County Public Works acquired four parcels of land in the lower Little Bear Creek Watershed near Woodinville. The 17 acres acquired was used as part of an advance mitigation effort. This project restored wetlands and stream habitat on the site, preserved other areas, and enhanced some areas to compensate for impacts associated with future roadway projects.

Restoration efforts required years of collaboration among county, federal, state, and local permitting agencies, local Tribes, and consulting design engineers at ESA Associates. Since work began in 2019, construction activities have:

Removed 17 structures and associated utilities
Decommissioned a domestic well and a hand dug well
Cleared more than 4.25 acres of wetland fill
Removed 0.86 acres of impervious surface area
Removed approximately 1,200 linear feet of drain pipe and electrical conduit
Enhanced soil with 2,300 cubic yards of compost and 4,000 cubic yards of wood chip mulch
Installed more than 100 woody and boulder habitat features
Created and/or enhanced 10 permanently or seasonally flooded shallow depressions to support wildlife
Created a floodplain bench and two large wood structures to improve flood dispersion and provide refuge for juvenile salmonoids
Enhanced two perennial tributary streams and acres of wetlands
Planted more than 21,000 native trees and shrubs

The completed work is projected to save the county more than $450,000 in mitigation costs for the first two projects that will use the site (Alderwood Mall Parkway and 43rd Ave SE corridor improvement projects). A minimum of 10 other Public Works projects are expected to avoid or greatly reduce mitigation costs through credits generated in the future.

Public Works staff will continue to monitor the project area during the next 10 years to ensure that the site vegetation matures and other habitat features meet performance standards. The site will be protected in perpetuity and left in its natural state as a conservation area.

Schedule

2019: Demolition of buildings
Summer 2022: Restoration construction
Fall 2022: Installation of more than 21,000 native plants

Traffic Impact

There were single-lane closures at the intersection of 238th St SE and 58th Ave in July 2022. Crews re-graded the adjacent hill to improve site distance.

Funding

Funding for this project was provided by the Snohomish County Road Fund.

Environmental Review

An environmental review of the Little Bear Creek Advance Mitigation Site (RC 1730) was completed in compliance with the State Environmental Policy Act (SEPA). SEPA requires that all state and local agencies identify and evaluate the environmental impacts of their land use decisions. An Environmental Checklist was prepared and a Determination of Non-Significance was issued for this project. These documents are available by viewing the links below.