Mid Spencer Island Estuary

Mid Spencer Island Estuary Overview

The Mid Spencer Island Estuary project is part of a larger group of related projects. Levees were built decades ago to protect cattle from tidal activity. With no natural drainage, heavy rains and tidal activity brought on extreme flooding to the islands. When the waters receded, they left behind fish and aquatic life, trapped on land and easy pickings for predators, which diminished their numbers. The goal was to remove sections of the old levees and reconnect the historic interior channels, add wood habitat features, and increase topographical diversity.

Site Conditions

Spencer Island had no roads or bridges to access it so everything had to be done via the waterways. A barge was used to transport all equipment and our teams to the worksite with jet boats ferrying materials and supplies. Due to the soil conditions within Spencer Island that included very soft silts and shallow waters, we were unable to use standard heavy equipment and had to improvise.

Means and Methods

The specialized equipment selected for this site were two mid-sized amphibious excavators owned by BCI; a 200 class Remu and a JD 160 class John Deere.

These amphibious excavators were used to remove sections of the failing levee. An existing perimeter dyke was breached to connect historic interior channels. As floods occur prospectively, the water’s natural movement and energy will break down the failing levees, thus enhancing the goals of this project without the cost of removing miles of levees.

Final Results

The project site has been restored to a fully functioning estuarine wetland with complete tidal exchange between Union Slough and Mid Spenser Island. The interior channels are now fully connected reestablishing intertidal wetlands providing habitat for a mixture of waterfowl, raptor bird species, shorebirds, and aquatic mammals attracted to estuarine habitats. The improved habitat provides off-channel rearing habitat essential for juvenile salmon acting as areas for fish to rest, feed, and reproduce.