Regression relations were determined for estimating mean annual discharge, mean monthly discharge, minimum and maximum 7-day discharge, flow duration series, and peak discharge for natural streams in western Colorado. Multiple regression analyses were used to determine the best predictive relations for each of the streamflow characteristic; separate relations were developed for each of four hydrologically distinct regions in the study area. The standard errors associated with the regression relations generally were less than 100 percent, except for the low-flow relations which had standard errors ranging from 62 to greater than 200 percent. Basin drainage area, mean annual precipitation , mean basin elevation, and mean basin slope are used in the regression relations to estimate the flow characteristics of streams in the study area. (USGS)