Before the construction of the La Loutre Dam in 1916, creating the Gouin Reservoir, Lake Simard had a smaller dimension. After the second raising of the waters in 1946 with the development of the Gouin Dam, Lake Simard took its present form.

The main hydrographic slopes near Lake Simard are:

• north side: Piponisiw River, Miller Lake, Plamondon Creek (Gouin Reservoir), Pascagama River, De la Rencontre Creek;
• east side: Miller Lake (Gouin Reservoir), Du Mâle Lake (Gouin Reservoir), Bourgeois Lake (Gouin Reservoir), Toussaint Lake;
• South side: Du Mâle Lake (Gouin Reservoir), Plamondon Bay (Gouin Reservoir), Kaopatinak Pass;
• west side: Plamondon Creek (Gouin Reservoir), Berthelot River, Pascagama River.

With a length of 4.2 kilometres (2.6 mi) (with a deformed outline and several bays, islands and peninsulas), Lake Simard stretches in the North-South direction. This lake is mainly fed by the Piponisiw River, coming from the North.

The Lake Simard is bounded on the east side by a peninsula stretching northward on 5.1 kilometres (3.2 mi) to Miller Lake (Gouin Reservoir), where the current flows through a narrow passage towards the East is located, either to the Du Mâle Lake (Gouin Reservoir). On the west side, a mountain peak rises to an altitude of 505 metres (1,657 ft) at 2.0 kilometres (1.2 mi) from the shore of the lake. The water level of the lake equilibrates with that of the Gouin Reservoir, except when the level is lowered (eg at the end of winter) according to the water management of the Gouin Dam.

The mouth of Lake Simard is located northeast of the lake, at:

• 3.2 kilometres (2.0 mi) west of the mouth of Miller Lake (Gouin Reservoir) (confluence with the Du Mâle Lake (Gouin Reservoir);
• 9.7 kilometres (6.0 mi) north of the exit of the Kaopatinak Pass which separates the Du Mâle Lake (Gouin Reservoir) in two;
• 17.0 kilometres (10.6 mi) south-west of the village center of Obedjiwan, Quebec which is located on a peninsula on the north shore of Gouin Reservoir;
• 86.0 kilometres (53.4 mi) west of Gouin Dam;
• 132 kilometres (82 mi) northwest of the village center of Wemotaci, Quebec (north shore of the Saint-Maurice River);
• 223 kilometres (139 mi) north-west of downtown La Tuque;
• 323 kilometres (201 mi) northwest of the mouth of the Saint-Maurice River (confluence with the St. Lawrence River at Trois-Rivières).^[1]

From the mouth of Lake Simard, the current flows over 101.5 kilometres (63.1 mi) to Gouin Dam, according to the following segments:

• 2.3 kilometres (1.4 mi) to North-East, crossing the Miller Lake (Gouin Reservoir), to the mouth;
• 17.3 kilometres (10.7 mi) to the East crossing the Du Mâle Lake (Gouin Reservoir), Bourgeois Lake (Gouin Reservoir) and Toussaint Lake to the South of the village of Obedjiwan, Quebec;
• 81.9 kilometres (50.9 mi) to the east, crossing in particular Marmette Lake, then to the South-East crossing notably Brochu Lake, then going across the Kikendatch Bay until Gouin Dam.

From this dam, the current flows along the Saint-Maurice River to Trois-Rivières where it flows onto the North Shore of the St. Lawrence River.

• Saint-Maurice River, a watercourse
• Gouin Reservoir, a body of water
• Toussaint Lake, a body of water
• Bourgeois Lake (Gouin Reservoir), a body of water
• Du Mâle Lake (Gouin Reservoir), a body of water
• Piponisiw River, a body of water
• La Tuque, a city
• List of lakes in Canada