Seymour Lake is located in the town of Morgan in Orleans County, Vermont, an area known as the Northeast Kingdom. The lake was named for Israel Seymour, one of the original grantees. Natives called it Namagonic ("salmon trout spearing place"). It is one of only two deep, cold, and oligotrophic lakes in the Clyde River system. A dam is used for hydroelectric power. Construction on the dam was completed in 1928. It has a normal surface area of 2.8 square miles (7.3 km2). It is owned by Citizens Utilities Company. The dam was rebuilt in 2004.