Imperial Dam was built to replace the Laguna Diversion Dam, built in 1901–1915, which was the first dam and reclamation project on the Colorado River. Imperial Dam was built with three sections; the gates of each section hold back the water to help divert the water towards the desilting plant. Three giant desilting basins and 72 scrapers hold and desilt the water; the removed silt is carried away by six sludge pipes running under the Colorado River that dump the sediment into the California sluiceway, which returns the silt to the Colorado River. The water is now directed back towards one of the three sections which divert the water into one of the three channels. About 90% of the volume of the Colorado River is diverted into the canals at this location. Diversions can top per second—more than 50 times the flow of the Rio Grande.