|Location||Merrimack County, New Hampshire|
|Primary outflows||Tributary of Merrimack River|
|Basin countries||United States|
|Max. length||2.3 miles (3.7 km)|
|Max. width||0.6 miles (1.0 km)|
|Surface area||362 acres (1.5 km2)|
|Surface elevation||402 feet (123 m)|
Penacook Lake is a 362-acre (1.5 km2) lake located in Merrimack County in central New Hampshire, United States, in the city of Concord. It has also been known as "Long Pond". It is the largest lake in Concord and serves as the city's water supply. Water that is not captured by the city's water treatment plant flows two-thirds of a mile to the Merrimack River.