From its source at Elwha snowfinger in the Olympic Mountains, it flows generally north to the Strait of Juan de Fuca.

[4] The river has already carried sediment to its mouth, creating 70 acres of estuary habitat at the Strait of Juan de Fuca.

The river flows southeast, then curves northward for the great majority of its course, with its mouth at the Strait of Juan de Fuca.

Lost River joins near the northern end of Press Valley, after which the Elwha crosses into Clallam County, Washington.

[9] The act authorized the Secretary of the Interior to acquire and remove the two dams on the river and restore the ecosystem and native anadromous fisheries.

Model projections by the Park Service show that up to 392,000 fish will fill 70 miles of habitat, theoretically matching the "pre-dam peak".

[9] By late December 2012, about 10 percent of the estimated 25,000,000 cubic yards (19,000,000 m3) of sediment that had been caught behind the river's two dams had collected at the Elwha's mouth, forming sandbars.

With the Elwha Dam removed, the sediment had been pushed downstream as heavy rainfall produced faster-moving flows in the free-running river.

[10] By November 2014, 30 percent of the stored sediment had been carried to the mouth of the river, creating 70 acres (28 hectares) of new estuary habitat for a wide variety of shellfish and other species.