Estimating Flow-Duration and Low-Flow Frequency Statistics for Unregulated Streams in Oregon

This report presents the results of statistical analyses used to compute period of record annual and monthly flow duration and low-flow frequency statistics at unregulated sites throughout Oregon. In addition to providing methods for calculating flow duration and low-flow frequency statistics from streamflow records, the report also describes the development of regression equations that relate basin physical and climatic characteristics to flow statistics. The report also provides a discussion of the accuracy and limitations of the flow statistics and regression equations.