Elwha Ecosystem Restoration - Sediment Load

Sediment Load

With the Glines Canyon Dam blocking sediment from reaching the Strait of Juan de Fuca for more than 80 years, most of it has been accumulating in Lake Mills. Historically, the sediment from the Elwha River would accumulate at the mouth of the river, expanding the delta and forming extensive sandy beaches. In addition, east-flowing currents would transport much of that sediment towards the bluffs of Port Angeles and onto Ediz Hook. However, since the sediment has been accumulating in Lake Mills, wave action and currents have eroded the beaches away until they have become nothing more than rocky or pebbly slopes. The mouth of the river has eroded back several acres over the years, shrinking the size of the Lower Elwha Klallam reservation and eliminating their once abundant clam beds.

Ediz Hook has also eroded away to the point that rip-rap has to be placed on the feature to protect Port Angeles harbor from the erosive effects of the wave action. The United States Army Corps of Engineers spends approximately $100,000 annually to control erosion of Ediz Hook and estimates the Elwha River contributed between 50,000 and 80,000 cubic yards of sediment per year before the dams were built. The dammed river contributes a negligible volume of sediment to Ediz Hook.