National Geographic : 1968 Jul
Taming a northwoods torrent, a 6,700 foot-long dam plugs the Peace River. Its name honors British Columbia's premier, W. A. C. Bennett. These cutaway drawings show the Portage Mountain project as it will stand when fully completed in the 1970's. In 1793 explorer Alexander Mackenzie portaged rapids in "this almost inaccessible country." Now as a reservoir floods 640 square miles, only a few trappers and pros pectors move out of the way. But already the promise of abundant power draws pulp mills and stimulates the development of rich farmlands and mineral resources nearby. GEOGRAPHIC ARTDIVISION© N.G.S . EKTACHROMES © NATIONALGEOGRAPHIC SOCIETY Acrobat on a web of steel, a construction worker ties reinforcing bars for the concrete lining of a penstock at Portage Mountain. Water will flow down the tube to a turbine buried 500 feet deep in solid rock. On the surface the work stops for winter, but under ground it continues year round to speed com pletion of the 725-million-dollar project. Sprayed from a gun, concrete coating will prevent erosion in the rock ceiling of a sub terranean chamber. Two such manifolds, each ten stories high, receive water from turbines and channel it back to the Peace River through tailraces. At the peak of con struction, almost 5,000 men worked on the dam, hydroelectric plant, and twin trans mission lines to Vancouver, 560 miles away.