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.

The Ohio River is a 981-mile-long (1,579 km) river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing in a southwesterly direction from western Pennsylvania to its mouth on the Mississippi River at the southern tip of Illinois. It is the third largest river by discharge volume in the United States and the largest tributary by volume of the north-south flowing Mississippi River, which divides the eastern from western United States. It is also the 6th oldest river on the North American continent. The river flows through or along the border of six states, and its drainage basin includes parts of 14 states. Through its largest tributary, the Tennessee River, the basin includes several states of the southeastern U.S. It is the source of drinking water for five million people.