Milltown Island, located in the South Fork Skagit River estuary, was acquired by the Washington Department of Fish and Wildlife in the late 1940’s after numerous years of diking efforts (beginning in the late 1800’s) and intermittent farming. The presence of the levees around the perimeter of the island has isolated the interior from the hydrological forces of the Skagit River and the Skagit Bay tides. Milltown Island can be divided into northern (~160 acres) and southern (~153 acres) portions (see map below).

Key objectives for the project include:

1. Remove or reduce artificial hydrologic controls in the diked portion of Milltown Island through levee removal or perforation.
2. Encourage channel development in the diked area in order to restore the quantity and quality of habitat for anadromous fish.
3. Restore natural vegetative communities through plantings and control of invasive species.

Map showing restoration work completed in the northern and southern portions of Milltown Island.

Due to very difficult access for heavy equipment, it was decided that the use of explosives would best allow project objectives to be accomplished. Demolitions occurred during an accepted in-water work window of August 15 through September 30 for both 2006 and 2007. Actual blasting events were scheduled during daytime low-low tides to further limit any possible impact of the explosives on local fish populations. To prepare for demolition work, a series of six inch diameter holes were bored to a depth of 100 to 120 percent of the levee height (approximately six feet) with a hydraulic auger. The interior channels were bored to a depth of three feet with hand-held augers. The explosive packages were hand assembled, inserted into the prepared holes and backfilled, and then detonated by a local explosives contractor. Expended demolition materials were collected and properly disposed of. The completed project removed 1,050 feet of levee and created 3,200 feet of new channels.

Excavation of interior marsh channels using explosives, summer 2007.

Project Status/Timeline
Dike removal and channel construction began in the summer of 2006 and were concluded in the summer of 2007. Native plants, mostly willows and other hardy, fast-growing shrubs were installed in areas disturbed by demolitions activities (3,850 stems in January 2007 and 5,750 stems in January 2008). On-going monitoring efforts will track channel development, plant community development and fish usage.

A newly-excavated interior marsh channel

The same channel, following several months of tide cycles and vegetation growth.

Primary Project Contact
Jef Parr / Nora Kammer (Monitoring)

Funding Sources
Seattle City Light
Salmon Recovery Funding Board

Project Partners
Washington Department of Fish and Wildlife

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