Sibley Lake Dam is a dam in Natchitoches Parish, Louisiana. The earthen dam was constructed in 1962 with a height of 36 feet and a length at its crest of 6,520 feet. It impounds the Youngs Bayou for municipal water supply for the city of Natchitoches. The dam is owned and operated by the city and local Water Works District Number One. Both lake and dam …Sibley Lake Dam is a dam in Natchitoches Parish, Louisiana. The earthen dam was constructed in 1962 with a height of 36 feet and a length at its crest of 6,520 feet. It impounds the Youngs Bayou for municipal water supply for the city of Natchitoches. The dam is owned and operated by the city and local Water Works District Number One. Both lake and dam are named for an early settler and Indian agent in the area, Dr. John Sibley.