The effects of three historical droughts on streamflows available for instream use on the lower Neosho River at Iola and Parsons, Kansas, were investigated. Natural streamflows that occurred during the three droughts were compared to the multiple-use and water-quality streamflows recommended by State agencies. A reservoir model was used to investigate the effects of John Redmond Reservoir on the natural streamflows. The regulated streamflow produced from the reservoir model then was compared to the multiple-use and water-quality streamflows. The regulated streamflows usually satisfied the multiple-use and water-quality streamflows more often than the natural streamflows. Frequency analysis made on the natural and regulated streamflows showed that the number of days of low flow (less than 30 cubic feet per second) were reduced by the regulated streamflows, which aided in the achievement of the multiple-use and water-quality streamflows goals. The reservoir model was used to determine if sufficient storage was available in John Redmond Reservoir to modify the natural streamflows in order to satisfy the multiple-use and water-quality streamflow recommendations. Additional storage of 15,400 acre-feet was estimated to be needed to maintain the multiple-use streamflows at Parsons.
