The Toutle River begins at the confluence of the North Fork Toutle River and the South Fork Toutle River near the community of Toutle. The forks originate on Mount St. Helens in Mount St. Helens National Volcanic Monument, and flow generally west to form the main stem, which continues generally west, with significant north-south deviations. The town of Toutle lies to the left of the river at river mile (RM) 17.2 or river kilometer (RK) 27.7.