<P> Two artificial lakes are key parts of the canal: Gatun and Miraflores Lakes . Four dams were constructed to create them . Two small dams at Miraflores impound Miraflores Lake, and a dam at Pedro Miguel encloses the south end of the Culebra Cut (essentially an arm of Lake Gatun). The Gatun Dam is the main dam blocking the original course of the Chagres River, creating Gatun Lake . </P> <P> The Miraflores dams are an 825 - metre (2,707 ft) earth dam connecting the Miraflores Locks in the west and a 150 - metre (492 ft) concrete spillway dam east of the locks . The concrete dam has eight floodgates, similar to those on the Gatun spillway . The earthen, 430 - metre (1,411 ft) Pedro Miguel dam extends from a hill in the west to the lock . Its face is protected by rock riprap at the water level . The largest and most challenging of the dams is the Gatun Dam . This earthen dam, 640 metres (2,100 ft) thick at the base and 2,300 metres (7,546 ft) long along the top, was the largest of its kind in the world when the canal opened . </P> <P> Building the locks began with the first concrete laid at Gatun on August 24, 1909 . The Gatun locks are built into a cutting into a hill bordering the lake, requiring the excavation of 3,800,000 m (4,970,212 cu yd) of material (mostly rock). The locks were made of 1,564,400 m (2,046,158 cu yd) of concrete, with an extensive system of electric railways and cable cars transporting concrete to the lock - construction sites . </P> <P> The Pacific - side locks were finished first: the single flight at Pedro Miguel in 1911, and Miraflores in May 1913 . The seagoing tugboat Gatun, an Atlantic - entrance tug used to haul barges, traversed the Gatun locks on September 26, 1913 . The trip was successful, although the valves were controlled manually; the central control board was not yet ready . </P>

Who was in charge of building the panama canal