Low-flow characteristics of streams in the Lake Michigan basin are presented. Included are estimates of low-flow frequency at 30 gaging stations, flow duration at 13 gaging stations, and selected low-flow frequency characteristics at 22 low-flow partial-record stations and 123 miscellaneous sites. Equations are provided to estimate low-flow characteristics at sites where one base-flow discharge measurement is available. The equations were determined from multiple-regression analyses that related low-flow characteristics at gaging stations and low-flow partial-record stations to basin characteristics. Drainage area and base-flow index were the most significant characteristics in explaining the variation in low flow for sites where one low base-flow measurement (flow durations greater than 80%) has been made. The equations and corresponding standard errors of estimate are computed. Low-flow characteristics are not well defined in the Lake Michigan basin. Standard errors for low-flow characteristics at gaging stations, low-flow partial-record stations, and miscellaneous sites are much higher than State averages. The standard errors for the regression equations are also very high. This is due in part to the flow of many streams in the basin approaching 0 ft/s during low base-flow periods. The graphical regression relation lines are steep for stations on these streams and the resulting standard errors are relatively high. (USGS).
