The tri-state water dispute is a 21st-century water-use conflict among the U.S. states of Georgia, Alabama, and Florida over flows in the Apalachicola-Chattahoochee-Flint River Basin and the Alabama-Coosa-Tallapoosa River Basin. The U.S. Army Corps of Engineers has regulated water flow for the entire Chattahoochee River, from Lake Lanier in Forsyth County, Georgia, to Alabama and Florida.
The states filed suit in 1990 in their conflict over the water supply; federal courts has affirmed the Corps' authority to negotiate the conflict. As the Lake Lanier project was authorized by Congress, each of the three states is entitled to an equal portion of the water; the project was never envisioned only to benefit metropolitan Atlanta, the closest large city and one that has developed rapidly since the late 20th century, greatly increasing its water consumption. The water flows are also regulated to support a variety of uses by states downriver, including preservation of marine life under the Endangered Species Act, and support for major seafood industries.