An incoming tide flowing beneath the bridged outlet channel opening at the Crescent Harbor Salt Marsh.
An incoming tide flowing beneath the bridged outlet channel opening at the Crescent Harbor Salt Marsh.

 

The Crescent Harbor Salt Marsh was once the largest barrier salt marsh on Whidbey Island. Barrier salt marshes play a large role in supporting small ocean-type salmon, particularly Chinook, once these salmonids move away from large river deltas. Historically, the Crescent Harbor Salt Marsh site was hydraulically connected to Crescent Harbor by a channel located in the southwestern portion of the marsh. Around 1910, the marsh was diked and ditched for agricultural use, and the channel inlet was filled and replaced with a tidegate in the southeastern portion of the marsh. This allowed seasonal management of on-site water levels and blockage of flood tide flows. Site drainage was improved through ditching. Subsequently, muted tidal volumes and sediment transport have led to marsh surface subsidence to about three feet below natural marsh elevations due to soil decomposition and compaction (Heatwole 2004). Although the Navy secured the tide gate partially open in 1993 to allow some tidal exchange, the small opening, small-diameter culverts, and blockage by mussels and barnacles led to extremely muted tidal flow to marsh surfaces.

In partnership with Naval Air Station Whidbey Island, SRSC secured resources through the Salmon Recovery Funding Board (SRFB) and the Estuary and Salmon Restoration Program (ESRP) to build upon an initial assessment completed by Island County Public Works and Philip Williams and Associates (2003), to implement the following restoration actions:

  1. Creating notched weirs at the sewer intake dike separating the southwest and the northwest salt marsh cells to allow tidal circulation.
  2. Breaching a sewer intake dike connecting the east and northwest marsh cells to increase tidal volume and fish access.
  3. Replacing a small culvert currently connecting the southwest and east salt marsh cells to improve fish access and tidal circulation.
  4. Breaching the remaining beach berm near the existing tide gate and reconnecting the existing channel network to Crescent Harbor through the Seabee bridge.

In 2008-2009, the SRSC completed these construction actions to restore tidal flooding and fish access to more than 200 acres of the Crescent Harbor Salt Marsh. Site monitoring and adaptive management are ongoing at the site.

2007 (pre-project) and 2010 (post-project) photos of the Crescent Harbor Salt Marsh restoration site.
2007 (pre-project) and 2010 (post-project) photos of the Crescent Harbor Salt Marsh restoration site.

 

Project Status/Timeline
In 2008-2009, the SRSC completed construction actions to restore tidal flooding and fish access to more than 200 acres of the Crescent Harbor Salt Marsh. Site monitoring and adaptive management are ongoing at the site.

Primary Project Contact
Eric Mickelson – Restoration Ecologist

Funding Sources
SRFB – Salmon Recovery Funding Board
ESRP – Estuary and Salmon Restoration Program
Department of Defense – US Navy
PSNERP – Puget Sound Nearshore Ecosystem Restoration Project

Project Partners
Naval Air Station Whidbey Island – US Navy

References

Beamer, EM, B Brown, K Wolf, R Henderson, C Ruff. 2016. Juvenile Chinook salmon and nearshore fish use in habitat associated with Crescent Harbor Salt Marsh, 2011 through 2015.

Clifton, B. 2015. Crescent Harbor Salt Marsh Restoration: 2013-2015 Vegetation Monitoring Report.

Crescent Bay Salt Marsh and Salmon Habitat Restoration Plan. Prepared by Philip Williams & Associates, Ltd. and the University of Washington Wetland Ecosystem Team (UW-WET). July 14, 2003.