The Miami Conservancy District is a river management agency operating in Southwest Ohio to control flooding of the Great Miami River and its tributaries. It was organized in 1915 following the catastrophic Great Dayton Flood of the Great Miami River in March 1913, which hit Dayton, Ohio particularly hard. Designed by Arthur Ernest Morgan, the Miami Conservancy District built levees, straightened the river channel throughout the Miami Valley, and built five dry dams on various tributaries to control flooding. The district and its projects are unusual in that they were funded almost entirely by local tax initiatives, unlike similar projects elsewhere which were funded by the federal government and coordinated by the U.S. Army Corps of Engineers.

The Great Miami River is a tributary of the Ohio River, approximately 160 miles (260 km) long, in southwestern Ohio and Indiana in the United States. The Great Miami originates at the man-made Indian Lake and flows south through the cities of Sidney, Piqua, Troy, Dayton, Middletown and Hamilton.