DESCRIPTION
The primary objective of this project is to increase the amount and quality of salt marsh habitats available to juvenile salmon in Admiralty Inlet. A series of dikes has truncated tidal influence in the western lobe of Deer Lagoon, limiting its value as habitat for juvenile salmon. These dikes have resulted in the loss over 450 acres of potential salt marsh and mudflat habitat in the western lobe of Deer Lagoon. These dikes have also degraded ~100 acres of existing salt marsh on their seaward side, through decreased tidal prism. The reduction of flushing power (sediment transport capacity) from lost tidal prism has decreased the width and depth of the opening of the lagoon, as well as decreasing channel depths throughout the remnant marsh.The first phase of this project examined flood risk to private property adjacent to the lagoon. Modeling during this phase has shown that all of the project alternatives that would result in meaningful nearshore restoration would require the construction of a setback levee to protect homes on adjacent properties from flooding during extreme high tide events. The grant request in this proposal would fund a geotechnical assessment of constructing a setback levee at Deer Lagoon as well as further refinement of the restoration conceptual design. The geotechnical assessment would include an evaluation of the existing levee system, subsurface explorations, a characterization of of soil geotechnical and hydrogeologic properties, and a settlement and stability analysis.