The U.S. Geological Survey (USGS) compiled data from a variety of national and state agencies to create a comprehensive dataset of streamflow and stage for the lower Columbia River basin and the coasts of Washington, Oregon, and northern California. Seasonal maximum values were calculated for streamflow and stage for the winter (November-March) and spring (April-July) flow seasons, as well as for the full water year (October-September) when underlying data were available.