Harrington Lake, also known as Lac Mousseau, is the official country residence of the Prime Minister of Canada. Located in the Gatineau Hills of Chelsea, Quebec, within Gatineau Park, the estate is situated approximately 35 kilometers (22 miles) northwest of Ottawa. It serves as a private retreat for the Prime Minister and is frequently used for hosting foreign dignitaries and holding informal government meetings.
The property and the lake are named after the Harrington family, who settled in the area in the 19th century. In the early 20th century, the land was acquired by Cameron Edwards, a lumber businessman, who constructed a colonial-revival style cottage on the site in 1925. The estate was later owned by William Hubert Moore before being acquired by the Canadian federal government in 1951 as part of the expansion of Gatineau Park. In 1959, Prime Minister John Diefenbaker designated Harrington Lake as the official country residence for the Prime Minister.
The estate is managed by the National Capital Commission (NCC), a federal Crown corporation responsible for the administration of lands and buildings in the National Capital Region. The site consists of the main residence, several guest cottages, and various outbuildings. For security and privacy reasons, the grounds are not open to the public, and access is strictly regulated.
Throughout its history as a state residence, Harrington Lake has been the site of significant political discussions. It has hosted various international leaders and served as a venue for cabinet retreats and the drafting of policy initiatives. While the property underwent extensive renovations starting in 2020 to address structural and system requirements, it remains a designated heritage site under the protection of the NCC.