3's powerhouse is actually located several miles downstream from the dam, and is fed by a 2.5-mile (4.0 km) conduit that carries water to it from the reservoir.

3 was built 4.2 miles (6.8 km) downstream from the dam in order to obtain maximum utilization of the elevation loss along this stretch of the river.

A high pressure conduit— most of which flows through a 12-foot (3.7 m) by 12-foot (3.7 m) tunnel carved into the mountainside— carries the water from the reservoir at a relatively steady elevation.

The water emerges from the tunnel at a point 2.5 miles (4.0 km) from the reservoir intake and drops 180 feet (55 m) through a steel penstock to the powerhouse's lone turbine.

[2] The rapid-flowing Ocoee River's hydroelectric potential has been exploited by private interests, namely the Eastern Tennessee Power Company and its successor, the Tennessee Electric Power Company (TEPCO), since the completion of Ocoee Dam No.

In 1939, a U.S. Supreme Court ruling forced TEPCO to sell TVA its assets, which included the tract for Ocoee No.

3 site as part of its Hiwassee Valley surveys in 1934, the idea for the dam received little attention until the outbreak of World War II in Europe sparked a need for increased aluminum production at the ALCOA plant in Alcoa, Tennessee, which required large amounts of electricity.

The diversion tunnel was completed in November of the same year, but budget delays prevented the dam's generator from becoming operational until April 30, 1943.

[2] On January 4, 2009, TVA released a substantial amount of contaminated sludge-like material from the Ocoee No.

The sludge was filled with contaminants— including copper, iron, and zinc— left over from the mining operations that once denuded the Ducktown Basin, which is adjacent to the Ocoee No.

On January 12, 2009, in response to the incident, the Tennessee Department of Environment and Conservation issued a notice of violation that ordered TVA to get state approval before using the dam's sluice gates, restore the affected areas, and submit a management plan for sluicing operations at the dam.