Hydrograph Separation of Selected Continuous Discharge Sites in the Colombia Plateau Region of the Pacific Northwest

This data release contains the results from hydrograph separation analysis for 44 separate sites within the Columbia Plateau region of the Pacific Northwest. The hydrograph separation program (HYSEP) (Sloto and Crouse, 1996) was used to perform baseflow separation. HYSEP is an automated approach to traditional graphical hydrograph separation methods and was utilized for this study. For the steady-state datasets a single average is provided for each of the individual streamgages. For the transient datasets, a monthly average is provided for each streamgage for the month-year pair when the gage is active. If a streamgage is missing more than 25% of the daily values for the month it is excluded from the record. Additional data subsets are provided for steady-state and transient simulations where average values for sites with available data between 2000-2007 and post 1980 for the transient simulation.