Low-flow and peak-flow frequency data and flow-duration-data, based on records from 21 gaging stations in the Joplin area of southwestern Missouri, are presented. Generalized equations and graphs based on gaging-station records are-shown so that estimates of frequency data and the effects of urbanization on peak flows can be made at ungaged sites. An analysis of a histogram of annual flood peaks shows that the chances for delay in construction work due to flooding are greatest during April through June and in September.