The Don Pedro Project consists of a dam and reservoir on California’s Tuolumne River that generate electricity and supply water for irrigation and domestic use. The project requires an operating license from the Federal Energy Regulatory Commission (FERC) that must be renewed every 50 years. As part of the license renewal process, FISHBIO conducted a tracking study of adult rainbow trout in the lower Tuolumne River for the Turlock and Modesto Irrigation Districts, which operate the Don Pedro Project. We captured fish and surgically implanted acoustic transmitters in the field, then tracked fish movements with mobile and fixed acoustic receivers to evaluate their migration characteristics. Study objectives were to determine the spawning locations and extent of in-stream movements of tagged adult rainbow trout, as well as their use of restored river reaches.