Elk watch as excavators remove the Willapa River dike.
Photo by Anitra Gorham
Pacific County, near South Bend
An estuary that has been diked for almost 100 years has now been restored to its
Washington Department of Wildlife (WDFW), Washington Department of
Transportation (WSDOT), Ducks Unlimited (DU), Natural Resources Conservation
Service (NRCS), Conservation Commission, and Clark
Conservation District (CCD)
An estimated 80% of the estuarine wetlands along the Willapa River have been
lost during the last century due to diking and draining. In 1912 a river dike
was constructed along the Willapa River, isolating several hundred acres of
former estuary from the tides. The Willapa Estuary Restoration project provided
an opportunity to restore the hydrology to almost 300 acres that
had been converted to pasture.
Six adjacent private landowners applied for the Wetland Reserve Program (WRP)
and were granted conservation easements. The landowners sold the fee title on
the property to WDFW. The WRP funded studies and designs, and then
construction activities to restore the estuary and freshwater wetlands. The
highway raising portion of the project, vital to the estuary restoration, was
funded through WSDOT.
Because this project was intended to flood with the tides, prior to the final
phase of restoration in 2008, a cross dike had to be constructed at the north end
of the project. The cross dike was built to protect neighboring properties from
flooding. In addition, Highway 101 was raised so that it would not be overtopped during
high tides. The construction contractor for the final dike removal and channel
reconnection was faced with deep mud, constant dewatering, variable tides, and
an untimely rain in August, which halted construction for almost two weeks.
Working on mats, excavating at low tide, and keeping the interior remnant
channels as dewatered as possible, allowed the final dike removal to be completed
during low tides in September. Material removed from the dike and channels was
used to fill some of the on-site drainage ditches and the borrow ditch left from
construction of the original river dike.
This project restored hydrology to almost 300 acres of estuary. Native plant
communities will establish naturally over time, providing more of this
diminished habitat type. The readily accessible nature of the site near highway
101 will allow it to be an invaluable learning tool as restoration progresses.