Gilligan Floodplain Restoration
This project is located on a large parcel of land that was acquired by the Forest Service for conservation purposes on the left bank of the Skagit River just downstream from Gilligan Creek. This parcel has an erosion control dike and rip-rap bank protection structure that is degrading natural bank conditions and preventing habitat creation through the natural processes of erosion and channel migration. The dike also limits the connection between the river and existing floodplain habitats during all but the largest flood events. This parcel was previously managed as a hybrid cottonwood plantation. The lack of species diversity in the floodplain reduces the quality of large woody debris, shade, and nutrient contributions to the Skagit River and to two fish-bearing streams (Stevens and Salmon creeks) that are located on the site.
The purpose of this project is to restore floodplain processes, restore connectivity to an existing floodplain channel, improve floodplain forest conditions, and reduce recreational impacts to spawning gravel at the site. The primary project activity will be removal of all or a portion of the dike and associated rip-rap bank protection on the main channel of the river. This will restore natural bank conditions, increase connectivity with floodplain wetlands and channels on 170 acres, and allow the river to create off-channel habitats through the natural processes of erosion and channel migration. Additional project activities include restoring diverse native forest vegetation to improve the supply of nutrients, shade, and large woody debris to the Skagit River and two fish-bearing streams. These activities will address important limiting factors and improve habitat conditions for Chinook and coho salmon and a variety of other fish species that use the Skagit River.
Map of Gilligan floodplain restoration project site.
Section of dike along the Skagit River at Gilligan Creek that is preventing natural processes of erosion and channel migration.
Project Status/Timeline
Funding has been acquired to conduct a feasibility study that will develop and evaluate alternatives to restore habitat at this site. This feasibility study will include completing a hydraulic model which will help identify downstream flooding and erosion. Hydraulic modeling will begin winter/spring of 2008 and is should take approximately 8 months to complete. Once completed, a preferred alternative can be chosen and funds will be sought for construction of that alternative.
Primary Project Contact
Devin Smith, Senior Restoration Ecologist
Funding Sources
Washington State Salmon Recovery Funding Board
Project Partners
United States Forest Service (Mt. Baker-Snoqualmie National Forest)