The Tolt River is located in the western foothills of the Cascade Mountains in north central King County in the U.S. state of Washington. The river begins at the confluence of the North Fork Tolt and South Fork Tolt rivers. It flows southwest joining the Snoqualmie River near Carnation, Washington. The Tolt River watershed is part of the larger Snohomish River and Puget Sound drainage basin. The name “Tolt” comes from the Lushootseed village name /túlq/.
The South Fork Tolt watershed provides drinking water for Seattle area residents.