Wynoochee River

The Wynoochee River is a 60 mi long river located in the Olympic Peninsula in the U.S. state of Washington. A tributary of the Chehalis River, the Wynoochee River rises in the Olympic Mountains within the Olympic National Park and flows generally south. Its drainage basin is 218 sqmi in area. The name Wynoochee comes from the Lower Chehalis placename /xʷənúɬč/, meaning "shifting".

The city of Montesano was a recipient of the installation of flood control measures near Montesano's wastewater treatment plant which rests near the river. As part of the Chehalis Basin Strategy, log jacks were placed during 2018-2019 that helped increase the riverbank of the migrating river, which was threatening the plant that during flooding would have inundated the community with sewage runoff. The fortification increased the habitat of aquatic species and extended the operating life of the plant by several decades.