Welcome to the Protection of Thirty-One Mile Lake Association website.



Mission Statement


The mission of “The Association for the Protection of 31 Mile Lake” is to protect the water, the fauna and the flora of the lake, to promote best environmental practices among lake dwellers and other users and to monitor the physical and chemical evolution of the lake water.


The lake in a few words

Lake Thirty-One Mile is a beautiful lake in the Vallée-de-la-Gatineau located east of the Gatineau River and bordered by the municipality of Déléage in the north and the town of Gracefield in the south. With a length of 29 km or 18 miles, it reaches about 6 km or 3.75 miles at its widest part. Its surface area is 4,973 hectares and its deepest point is 88 m. Oriented north-south, it straddles two (2) administrative regions (Laurentides and Outaouais), two (2) MRC (Antoine-Labelle and Vallée-de-la-Gatineau) and five (5) municipalities (Déléage, Ste-Thérèse-de-la-Gatineau, Bouchette, Gracefield and Notre-Dame-de-Pontmain). The lake’s watershed covers an area of 337 km2

We still do not know the origin of the name of Lake Thirty-One-Mile, but the name appears for the first time in an official document in 1852 in the English version of Thirty-One-Mile Lake. It was the map of the Blake Township prepared by the surveyor Alfred Driscolle.

The name Thirty-One-Mile was taken over by another surveyor, John O’Sullivan, in a description made in 1889. By cons, in 1863, Stanislas Drapeau named it Grand Lake indicating it at 22 miles long. Another survey report from 1870 written by Samuel B. Lucas reused the name Grand Lake. Our research has allowed us to know that the Algonquins have named it Lake Papenegoegawong or Papenegean which would mean something related to water falling or flowing. In 1908, the names of Grand Lake of the Commissioner or 31-Milles can be found on a map of the Cameron Township. The name Lake of the Commissioner is reported by Eugène Rouillard in a work entitled. “List of Geographical Names of the Province of Quebec,” published in 1925. Since Lake Pemichangan empties into the Thirty-One-Mile, the addition of two (2) lakes give 31 miles. An approximate measure from Google Earth gives us rather 36 km (22 miles). One source hypothesized that a certain point on the lake is located 31 miles from another unknown place thus serving as a mean of calculation.

The lake water level is regulated by a public dam (X0002894) that discharges in Lake Michel (Mitchell). The operation of the dam is managed by the Centre d’Expertise Hydrique du Québec. The dam width is 27 m and its height is 2.8 m. The first dam on the Thirty-One-Mile was built in 1910 by WC Edwards Co. Limited. This company located in Pembroke Ontario was founded in 1868 and it still owns and operates sawmills. In 1978, at the request of the Department of Recreation, Hunting and Fishing, the dam was rebuilt by the Ministry of Natural Resources. In 1984, the discharge capacity was increased and finally, a reconstruction occurred in 2009. Everything has been done in support of the cottages industry, but it particularly serves to maintain an appropriate water level on the lake trout spawning grounds. That is why the water level is gradually lowered from 1 September each year to 161.90 m above sea level. In the summer season, the water level is generally between 162.12 m and 162.18 m. The total variation is around 30 cm.

On the economic front, the Lake Thirty-One-Mile is a major tourist attraction for the Vallée-de-la-Gatineau. Boaters, canoeists and kayakers, campers and of course fishermen are in abundance mainly due to the presence of lake trout. Cottages are an important economic contributor to local municipalities’ revenues. Assessment of waterfront properties accounts for a large proportion of municipal budget revenues ranging from 53% to 72%. The cottagers’ contribution to the regional economy is not new. Commercial fishing existed on the Thirty-One-Mile in the late 1800s. Whitefish, lake trout, bass and pike were sold at the Ottawa market. Of course floating wood to local sawmill was a common practiced for many years.