DESCRIPTION
The Jamestown S'Klallam Tribe used this funding to construct seven large engineered logjams and two smaller ones in the vicinity of the Dungeness River Railroad Bridge near Sequim, WA. The purpose of these logjams is to create rearing habitat for juvienile salmonids and resting habitat for adult migrating salmon on the upstream side of the logjams and spawning habitat downstream of the jams. Additionally, upriver of the Railroad Bridge, as the riverbed reaggrades, side channels will be reactivated within the floodplain. This will open further spawning and rearing habitat.
As recently as the early 1980's, Clallam County regularly piled and burned large woody debris (LWD) in the Dungeness River. This contributed to a loss of structural complexity and LWD sufficiently sized to function in the river. Since then the habitat has been recovering, but it lacked stable logjams.
The 1.2% gradient in this reach is very active with frequent channel avulsions, a wide floodplain with multiple side channels, a substrate on average too large for spawning, and a range of riparian forest types and ages. The log jams act as hard points and have created salmonid high flow refugia and rearing pools within and upstream of each jam, gravel bars have been stabilized downstream of each jam for riparian forest establishment and further downstream, spawning. The network of jams has established a minimum level of channel complexity, sinuosity, and pool frequency that will remain regardless of the active channel position through time.