Hydrologic studies of the Delaware River Estuary have indicated that during low flow or drought periods, excessive salinity intrusion into the estuary may threaten water supplies in the Delaware River Basin. To assist in the pr evention of this excessive salinity intrusion, additional water supply storage to Prompton Reservoir has been proposed. This additional storage would raise the pool and possibly affect the thermal stratification and subsequent release temperature from the dam. To address this concern, a one-dimensional numerical model was used to simulate existing conditions and conditions with the proposed pool modification. An optimization routine coupled to the model was used to identify the optimum number and location of ports to maintain release temperatures within the State of Pennsylvania Water Quality Criteria. Results of the numerical simulations indicated a three-port structure with the ability to operate two ports simultaneously would meet the release criteria during a normal year. However, during a dry or drought year when the pool would be drawn down to meet downstream flow demands, a significant drop in the release temperature was predicted. To prevent this drop, two additional alternatives were examined: a submerged weir and lake destratification. The submerged weir did not improve the release temperature condition, but the destratification system when operated during the spring and early summer months did maintain release temperatures within criteria limits. The recommendations for this study were a three-port structure with the ability to operate two ports simultaneously and a destratification system to be operated during years in which the water supply storage is used.