Carters Lake is a man-made reservoir located on the Coosawattee River in the Blue Ridge Mountains in Gilmer and Murray counties in the U.S. state of Georgia. It is the state's deepest lake. While the reservoir is on the Coosawattee River, it empties directly into the Regulation Reservoir. The reservoir was named after Farrish Carter who lived in the 19th centur…Carters Lake is a man-made reservoir located on the Coosawattee River in the Blue Ridge Mountains in Gilmer and Murray counties in the U.S. state of Georgia. It is the state's deepest lake. While the reservoir is on the Coosawattee River, it empties directly into the Regulation Reservoir. The reservoir was named after Farrish Carter who lived in the 19th century. It has a surface area of 3,200 acres and has 62 miles of shoreline. Carters Lake has an average depth of 200 feet and a maximum depth of 450 feet.