The water issue has become a frontier of public debate globally due to public awareness of sustainable development. Nigeria's water resources are under serious threat from inadequate catchment management that includes widespread pollution from indiscriminate waste disposal. Stormwater is now recognized as a valuable resource rather than a nuisance, especially in large urban centers. Growing demand for water has exerted pressure on groundwater via dug well and boreholes scattered virtually in every dwelling in Nigeria. This challenge motivated this investigation of the feasibility of harvesting stormwater for due purposes of supplementing water supply and flash flood management. This study aims at quantification of harvestable stormwater and identification of potential capturing sites using Spatial Hydrological Analysis of GIS model and Synthetic Hydrograph. The result indicated total harvestable stormwater for 24-hr rainfall of 161.3 Mm3 and three available capturing sites of eight depressions identified. This volume is a good incentive to incorporate storm harvesting in overall water resources sustainable management.