The project began with Laguna Diversion Dam, an “Indian weir” design selected after engineers studied dams in other countries where the foundations were built on sand and silt. Over the millenniums the Colorado had deposited so much silt that it seemed financially impossible to dig to bedrock. A weir is a relatively small impoundment wall that has no control structures to permit passage of water through the wall. Any excess water goes over the top. Measuring only 43 feet high with nearly two-thirds of the dam below the riverbed, Laguna resembles the Okla Weir across the Jumna River in India.Work began on July 19, 1905, with contractor J. G. White and Company shipping materials upriver from Yuma on a steamboat or overland by wagon. Laguna is a rockfill weir, meaning it is an embankment dam with rock as the primary construction material. When rock quarried at the dam site fractured with what historian Eric A. Stene says was “an annoying regularity,” the frustrated contractor lost money, missed deadlines and turned the project over to the five-year-old U.S. Reclamation Service, which capped the top of the dam with concrete when suitable rock ran out. The Reclamation Service (today’s Bureau of Reclamation) hired mostly Mexican-American workers and gained the cooperation of the Southern Pacific Railroad, which built a rail line to the construction site. A mile and a half below Laguna Dam, the Yuma Main Canal, constructed between 1907 and 1909, split into a second canal to serve the Fort Yuma Indian Reservation. In Yuma, the main canal split again into an East Main Canal and a West Main Canal, which ran to the Mexican border, about 20 miles distant. Yuma project canals continue to deliver irrigation water to about 68,000 acres, but today the water no longer is diverted at Laguna Dam. Imperial Dam, completed a few miles upstream from Laguna in 1938, does the job now. In 1941, diversions from Laguna Dam ended, and the outlet works were sealed permanently on June 23, 1948. Today, Laguna Dam serves to protect the toe of Imperial Dam and for partial regulation of river flows. “Farming as we know it would not have existed without [Laguna] dam,” Tom Davis, general manager of the Yuma County Water Users Association, told the Yuma Sun in 2009, the 100th anniversary of the dam. Laguna was the first on the Colorado, and many others would follow, including Hoover Dam in 1936, Parker Dam in 1938 and Davis Dam in 1950. “The combination,” Davis said, “tamed the river.” The benefits were not without a cost, as natural riparian regions of the Colorado suffered as water was diverted elsewhere. Now efforts are underway at Yuma Crossing National Heritage Area not only to restore the region’s East and West Wetlands, but to reconnect the city of Yuma to its river heritage. The Colorado always has been central to Yuma’s history. It was at Yuma, where the Gila River enters the Colorado, that a granite outcropping once provided a convenient place to cross the river, thus the name, “Yuma Crossing.” Indian people crossed here first, then Spanish explorers and Franciscan missionaries. The fur trapper Ewing Young crossed at Yuma in 1826 and the American general Stephen Kearney and his army came this way in 1846 during the Mexican War. Following the Treaty of Guadalupe-Hidalgo, which transferred much of the American Southwest from Mexico to the United States, the U.S. Army, in 1851, established Fort Yuma on a bluff overlooking the crossing from the California side of the river. A rope ferry ran to the Arizona side, where the town of Yuma (first called Colorado City and then Arizona City) grew up as a supply depot for the fort.