Rocky Gorge Reservoir is located on the Patuxent River in Howard, Montgomery, and Prince George's counties in Maryland, between Laurel and Burtonsville. The reservoir was created in 1952 by the construction of the T. Howard Duckett Dam on the Patuxent. The dam is visible from Interstate 95 near milemarker 34. Because of its close association wit…Rocky Gorge Reservoir is located on the Patuxent River in Howard, Montgomery, and Prince George's counties in Maryland, between Laurel and Burtonsville. The reservoir was created in 1952 by the construction of the T. Howard Duckett Dam on the Patuxent. The dam is visible from Interstate 95 near milemarker 34. Because of its close association with a dam by the name, the reservoir is sometimes called the T. Howard Duckett Reservoir. It has a surface area of 773 acres. The reservoir is maintained as a drinking water source by the Washington Suburban Sanitary Commission.