York Indian Rock Dam, located in York, Pennsylvania, is a Rockfill dam completed in 1942 by the US Army Corps of Engineers for Flood Risk Reduction on Codorus Creek. Standing at 83 feet tall and with a storage capacity of 48,000 acre-feet, the dam plays a crucial role in reducing the risk of flooding to downstream communities. However, despite its risk reduction measures, the dam still poses a high hazard potential, especially during high-volume releases from its spillway during significant storm events. In the event of a breach, downstream communities like York and Grantley could face devastating flooding, with the potential for swift and deep floodwaters overflowing levees and destroying key infrastructure.

To mitigate these risks, the US Army Corps of Engineers actively manages and monitors York Indian Rock Dam. Regular inspections, monitoring, and emergency response exercises are conducted to ensure the dam's integrity and preparedness for potential flood events. The Emergency Action Plan for the dam is regularly updated, and close monitoring of rainfall forecasts helps determine when high water events may occur to provide timely flood warnings to downstream communities. While the dam serves as a crucial flood risk reduction structure, the potential for catastrophic flooding in the event of a breach underscores the importance of ongoing risk management measures and preparedness efforts by the US Army Corps of Engineers to safeguard downstream communities along Codorus Creek.