Lake Granby is the largest storage reservoir in the Colorado-Big Thompson Project and the second largest water body in the state. Water is pumped from Lake Granby via the Farr Pump Plant to the Granby Pump Canal where it flows to Shadow Mountain Reservoir. Once it has reached Shadow Mountain Reservoir, water flows through a connecting channel to Grand Lake, then into the West Portal of the Alva B. Adams Tunnel.
Lake Granby is located on the Colorado River approximately 5 miles northeast of the Town of Granby. The Colorado River flows from Shadow Mountain Reservoir into Lake Granby on its northeast side and exists at Granby Dam near the Sunset Point boat launch.
Construction of the dam and reservoir cost $12.9 million and began in late 1942. Water was first stored in Lake Granby September of 1949.
Lake Granby has a capacity of 539,758 acre-feet, 7,260 surface acres, 40 miles of shoreline and a maximum depth of 221 feet.