The United States Geological Survey released a comprehensive dataset of base-flow and streamflow estimates for 471 streamgage sites across Oregon. The data include site information, water-year and daily estimates of base flow, and streamflow measurements. Water-year base-flow values offer the most reliable insight into how groundwater sustains flows in rivers and streams—especially during Oregon’s hot, dry summers. Base flow, the portion of streamflow fed by groundwater rather than rainfall or snowmelt, plays a critical role in maintaining healthy rivers and aquatic ecosystems year-round. This data release is a product of the Oregon Water Science Center's Statewide Groundwater Recharge study in cooperation with the Oregon Water Resources Department. 

Statewide base-flow estimates for Oregon, water years 1980–2023