Lake Francis is a reservoir on the Connecticut River in northern New Hampshire, United States. The lake is located in Coos County, east of the village of Pittsburg and along the boundary between the towns of Pittsburg and Clarksville.
The lake, impounded by Murphy Dam, covers nearly 2,000 acres (8 km2), and was built in 1940 as a flood control project. The 117-foot (36 m) earthen dam is owned by the state of New Hampshire DES Water Division and operated by the power company TransCanada. The capacity of the reservoir is 131,375 acre feet (0.162049 km3).
The lake is classified as a coldwater fishery, with observed species including rainbow trout, brown trout, landlocked salmon, lake trout, and chain pickerel.
The lake was mentioned as the site of a girls' camp in the movie The Manchurian Candidate.
Lake Francis State Park is located on the northeast side of the lake, where the Connecticut River flows in.