Canadian Forestry Journal, May, ipi6. 



521 



St. Maurice River Storage Dam 



■?;- By 



O. Lcfehre, 

 Chief Engineer, The Quebec Streams Commission. 



The St. Maurice river has a drain- 

 age area of 17,000 square miles. It 

 takes its rise at a distance of about 

 360 , miles north of Three Rivers. 

 Its head waters are from numerous 

 lakes whose elevation is about 1,300 

 feet above mean sea level. 



The river is remarkable for its 

 numerous falls and rapids, — two of 

 which are fully developed and a 

 third utilized only partially. Of the 

 two developed, one is at Shawinigan 

 with an available head of 150 feet 

 and the other is at Grand jMere with 

 a natural head of 40 feet, and a pos- 

 sible head of 75 feet to be available 

 as soon as the dam, now being 

 erected, is completed. 



The flow of the St. Maurice river 

 varies from 200.000 cubic feet per 

 second during highest water, to 

 6.000 cubic feet per second at low 

 water. The low water stages occur 

 usually during August and Septem- 

 ber and the winter months, this be- 

 ing the cause of heavy losses by the 

 industrial companies. It is proposed 

 to remedy this condition by the stor- 

 age of water in the upper part of the 

 river. 



In the summer of 1912, surveys 

 were carried out and a dam site 

 chosen immediately above the La 

 Loutre falls at a distance of 240 

 miles, by the river, from Three 

 Rivers, of 50 miles above the mouth 

 of the Manouan river, a tributary of 

 the St. Maurice, and about 40 niiles 

 due east of Parent Station on the 

 Transcontinental. 



This dam will store the waters 

 from a drainage basin of 3,650 

 square miles. The water thus stored 

 will be sufficient to regulate the 



minimum flow at Shawinigan to 

 12.000 cubic feet per "second. It 

 will decrease the power at Shawini- 

 gan. Grand- Mere and La Tuque by 

 67,000 horse-power-years. 



The dam will be of the type 

 known as gravity section, of Cy- 

 clopean masonry. Its maximum 

 section will be 80 feet above the bed 

 of the river, 60 feet wide at the base 

 and 20 feet wide at the top, the up- 

 stream face being vertical. 



The water at the dam site will be 

 raised 47 feet above the present low 

 water. The area of the flooded lands 

 will be 95 square miles, all Govern- 

 ment property. 



The crest of the dam will be 

 about 1.700 feet long at elevation 

 1.335 above mean sea level. The 

 weir is 840 feet long at elevation 

 1,325. The dam is provided with 10 

 b-.'tton sluices 12 feet by 7^/2 feet 

 wide and a log sluice. When the 

 reservoir is full it will have a sur- 

 face area of 300 square miles. 



AMiile the dam is being built for 

 power purposes it will benefit large- 

 ly the log driving operation on the 

 river St. Maurice. 



The storage dam is now under 

 contract which calls for the work to 

 be completed by the 1st of January, 

 1918. The Quebec Streams Com- 

 mission, acting for the Quebec Gov- 

 ernment, has contracts with the 

 Shawinigan Water & Power Com- 

 pany, the Laurentide Company and 

 the Brown Corporation for the use 

 of the storage water. The annual 

 revenue from these contracts will 

 leave a surplus after deduction is 

 made for interest, sinking fund and 

 maintenance. 



