Authorized by Congress in the Flood Control Act of 1938 and the Federal Water Pollution Control Act Amendments of 1961, John W. Flannagan Dam and Reservoir is a part of the Big Sandy flood protection system which also includes:
- North Fork of Pound Lake in Virginia
- Fishtrap Lake near Pikeville, Kentucky
- Dewey Lake near Prestonsburg, Kentucky
- Paintsville Lake near Paintsville, Kentucky
The United States Army Corps of Engineers designed and supervised construction of the dams, which began in 1960 and was completed by 1964. The Corps of Engineers now operates the Flannagan for the public’s benefit. The Dam provides flood protection and a clean and reliable supply of drinking water for the residents of Dickenson and Buchanan Counties. The lake also provides low-flow augmentation, fish & wildlife enhancement and recreation for the residents of Dickenson County.
The Dam is named after the late Congressman John Williams Flannagan, Jr. who served the people of the Ninth Virginia District from 1931 to 1949. Mr. Flannagan never lost an opportunity to remind his audience that he came from the highland of Southwest Virginia, the mountains he loved so well. The Dam is dedicated in memory of his assistance in creating this flood control project and many others in the Appalachian Highlands Region.