The Spring River is a short but significant tributary of the North Umpqua River in Douglas County in the U.S. state of Oregon. It begins at a spring complex in the Cascade Range on Pumice Flat in the Umpqua National Forest and flows north into the North Umpqua in Kelsay Valley, upstream of Lemolo Lake. Evidence suggests that nearby Thirsty Creek has an underground connection to the Spring River and that underground connections from other sources exist.