The Lac-St-Denis military base was located in Saint-Adolphe-d’Howard on top of the Lac St. Denis Mountain. It was constructed between 1949 and 1952 and began operating on July 1, 1952. The base was initially called No. 202 RCAF Radio Station Lac St. Joseph. It’s purpose was initially kept a secret, leading civilians to wonder if the facility was being used for nuclear weapons. The actual purpose was to monitor the airspace for enemy missiles and aircraft curing the Cold War era.  Eventually the RCAF would allow public tours, which alleviated concerns from the public. Civilians were able to access the property for various activities including use of the pool in the recreation centre. Golfing and bowling were also offered as recreational activities.

In October of 1952 the base’s named was changed to RCAF Station Lac St. Denis.

Children on the base were bused to Morin Heights School. Staff lived in a small community of residences on the shore of the lake with Private Married Quarters (PMQs) and barracks for single airmen and airwomen.

The base was part of the Pinetree Line which consisted of a network of 33 radar stations under Canadian-American jurisdiction extending along the 49th parallel. The radar base ceased operating in December of 1985 and was closed on August 1, 1986.

The remains of the former base can be found at GPS: 45.935168, -74.30833.