Author Institution: Department of Geography, University of Calgary, Allen County Planning CommissionAn attempt is made to analyze land use changes and resultant increases in peak water flow in an urbanizing area. The study compares land use, infiltration, and peak water flow for a 16 mile2 area centered on Bowling Green, Ohio, for 1950, before accelerated urban development, with the same area for 1969, after development. Peak water flow increases attributed to urban development on former agricultural land, and the resultant problems of drainage and excess water, are of specific concern. In the study area, a combination of near-level topography, clay-rich soils, and paved commercial areas produce a peak water flow greater than the capacity of storm drainage ditches. Storm drainage facilities are not adequate to handle the increased peak water flow caused by urban development demonstrating the need for proper land use planning prior to urban development