The "Lac des Commissaires" is located south of
Roberval, south of
Lac Saint-Jean and northeast of
La Tuque. Covering an area of and a length of , the lake stretches from north to south. Its maximum width is . Its shape has two parts, roughly of similar length. The southern end of the southern part of the lake ends in a narrow bay six kilometers long, curving west. The
route 155 connecting
La Tuque and
Chambord runs along the southern part of the lake. In the middle of the lake, in the northern part, the lake forms a bulge towards the East, designated "Hail Bay" or "Mirage Lake" (former name "Lac Quaquakamaksis"). The "Commissioners Dam" belongs to the Government of Quebec and is found at the outlet of Lac des Commissaires, which is the main source supplying the
Ouiatchouan River. The emissary of the Commissioners lake is the "Commissioners river". The
rivière des Commissaires flows at the limit of ranges 6 and 7, northeast to reach the south of
Bouchette Lake; the current flows opposite Île Bouchette (triangular island located near the west shore of the lake). The
Bouchette Lake is long in the north–south direction and a maximum width of . The village of
Lac-Bouchette is located on its eastern shore of lakes
Bouchette and Ouiatchouane. The mouth of
Bouchette Lake is located in its northern part and flows into the southern part of Lake Ouiatchouane. The latter flows from the north into the
Ouiatchouan River which flows north to reach
Lac Saint-Jean, northwest of the intersection of
route 155 and
route 169. The
Ouiatchouan River flows mainly in wooded areas, except the last two kilometers of its route which are agricultural in nature.
Dam of Lac des Commissaires Built in 1971, the Lac des Commissaires dam has a height of and a retention height of . The dam has a holding capacity of . This "Concrete-gravity" type dam on a rock foundation has a length of 198.7 m. The area of the reservoir retained by the dam is and the area of the catchment area is . This dam is operated by the "Center d 'expertise hydrique du Québec". == Toponymy ==