Shepaug Dam is a dam located between Newtown in Fairfield County and Southbury in New Haven County, Connecticut. The concrete dam was constructed in 1955 by the Connecticut Light and Power Company, with a height of 140 feet, and a length at its crest of 1412 feet. It impounds the Housatonic River and the Shepaug River for hydroelectric power. Th…Shepaug Dam is a dam located between Newtown in Fairfield County and Southbury in New Haven County, Connecticut. The concrete dam was constructed in 1955 by the Connecticut Light and Power Company, with a height of 140 feet, and a length at its crest of 1412 feet. It impounds the Housatonic River and the Shepaug River for hydroelectric power. The dam is owned and operated by the power company Northeast Utilities.