What is the most common primary purpose of dams in the United States?

The dominant purpose of dams in the United States is often flood control. Dams are engineered to hold back water and regulate river flows, which helps to prevent flooding in downstream areas. This mitigation of flood risk is crucial for protecting infrastructure, homes, and agricultural land from the potential devastation caused by high water levels during heavy rains or rapid snowmelt. Historically, this has been a significant priority for dam construction, particularly in areas prone to seasonal flooding.

Despite the importance of hydropower generation, recreation, and irrigation, the primary focus often lies in managing and controlling the risks associated with flooding. Many dams serve multiple functions, but flood control typically takes precedence as the primary purpose for many facilities across the country.