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Lower Granite Lock Size Information Handout, by U.S. Army Corps of Engineers

Another important part of Lower Granite Dam is the navigation lock. At 674 ft. in length, 86 ft. wide and 141.5 foot height this prominent feature allows commercial as well as well as recreational traffic to navigate up and down the waterway. Lower Granite's navigation lock has a maximum lifting capacity 105 ft., one of the highest lifts in the world. The lock has a 46 million gallon water capacity. Locking through takes about 20 minutes each way. Though the actual time to empty or fill is only 10 minutes. There are two fill valves and two drain valves to let the water in and out. Each valve controls a water passageway that is 12 feet wide by 14 feet high. Because the whole process is done by the gravitational fall of the water; there are no pumps involved, and therefore no energy expended. However, if the 46 million gallons used to operate the lock were run through the generators, it would produce 12 million watts an hour. This could supply an average household with electricity for half a year. Because of this substantial loss of generation occurs with each lockage there is a limited time schedule during the recreation season for recreational lockages.