Putah Creek is a small river running from Lake Berryessa through the town of Winters, along the UC Davis campus into the Yolo Bypass. Salmon were once abundant here but became extirpated due to habitat alteration and water diversions. Following on-going restoration efforts Chinook salmon have returned to Putah Creek for the third year in a row. Chinook salmon are well established in many rivers in the Central Valley and are supplemented with several large hatcheries. We conducted in-river surveys and collected otolith (fish ear stones) from carcasses to determine the origin of these pioneering salmon. Otoliths have daily growth increments and can provide a life-long archive of age, growth and environmental signatures. Strontium isotopes measured in otoliths enable us to reconstruct how fish move through habitats and to determine their origin. This project is being carried out in the OGFishlab at UC Davis in collaboration with Nann Fangue, Andrew Rypel, Eric Chapman and Emily Jacinto.