Prior to the initiation of translocation efforts in 2017, Pacific lamprey (Entosphenus tridentatus) were last documented in the Okanogan river subbasin in 2010. It appears as if lamprey were extirpated in the Okanogan subbasin some time shortly after that. However, until 2017, monitoring and management actions for lamprey were minimal in the Okanogan subbasin. This lack of monitoring has resulted in a large gap in understanding of the recent historical status of Pacific lamprey distribution throughout the Okanogan subbasin. Recent (beginning in 2017) translocation efforts have helped to rebound or reestablish lamprey in the Okanogan subbasin. Analysis of archived eDNA samples from the Okanogan river and its tributaries provides insight into the recent history of Pacific lamprey distribution and habitat preferences within the subbasin.