|Abstract||he Rainbow Trout, Oncorhynchus mykiss, is one of the most widespread freshwater fishes in the United States. Recent research has shown that anthropogenic actions are harming O. mykiss populations, but anadromous Steelhead populations are more adversely affected than resident Rainbow populations. In this study, we used Sanger sequencing to identify genomic locations that differed between a resident lake population and a migrant stream population of O. mykiss and subsequently utilized Double Mismatch Allele-Specific qPCR to genotype migrating smolts and identify from which population they originated. The DMAS-qPCR assays were successfully able to differentiate populations of origin and showed that 28.8% of smolts originated from the lake population. These results demonstrate conclusive proof that a resident population can and will produce migrant offspring, which may successfully reproduce to support struggling migrant populations, allowing for the development of new conservation management strategies.