In 1854, the
United States purchased the future Yuma Project's land in the
Gasden Purchase but had created the Fort Yuma Indian Reservation in 1884 to settle the indigenous
Quechan people. Much of the land was disputed in the 1890s and in 1910, the
Dawes Severalty Act opened the land to white settlers which led to further disputes. A series of court battles between the United States and the landholders led to the United States winning a decision and acquiring the land in 1898.
Levees A system of
levees was also constructed between 1907 and 1909 in order to protect the banks of the Colorado River from
flooding and its historical course-changing meandering. The Reservation levee was constructed on the west bank of the river between Lagunato and
Araz. The Yuma Valley levees were on the east bank of the river until the Colorado-
Gila River confluence and then to the Mexican border. To maintain the levees, the Bureau of Reclamation built rail lines on top of the Reservation levee so rail cars could reinforce or fill in problem areas. This proved successful during a major flood in 1912 and the Bureau asked Southern Pacific Railway if another line could be built on the Yuma Valley levee but they were reluctant. With its own acquired funding, the Bureau began to construct the Yuma Valley Railway in May 1914 and despite hot temperatures and wage strikes, construction was completed in February 1915.
Yuma Auxiliary Project Prior to completing the Laguna Diversion Dam, the Bureau of Reclamation began to consider the Yuma Auxiliary Project which would supplement the Yuma Project in order to
irrigate another of land called Yuma Mesa. Initial surveys of the Mesa began in 1916 and the
US Congress approved the Project in 1917. The Project was broken down in units A, B, C and D. Construction began on September 27, 1920, with the Mesa Supply Canal for unit B and in May 1922, the unit's
pumping station was also complete. Unit B irrigated as much as but development of the other three units never materialized. Only of canal and of lateral canals were built. In 1949, after the Laguna Dam ceased to divert water, the Yuma Auxiliary Project was reduced to just over in sized and the Gila Project took over its water supply.
Maintenance and the Imperial Dam change Flooding continued to be a problem for the Yuma Project. In January 1916, a flood larger than the one in 1912 caused in breaks on the Reservation Levee as the Gila River reached a maximum flow of . The river again flooded a few days later, reaching a flow of . Afterward, 10,000 of the Reservation Division was inundated while 3,000 of the Valley Division's flooded. The floods also displaced 50,000 yards of main canal. The Bureau of Reclamation worked quickly to restore the project in 15 days. In 1918, the Colorado River's meandering damaged part of the Reservation levee and it was repaired slowly with unskilled labor because of
World War I's troop demands. The Laguna Diversion Dam weathered the floods but its downstream
talus at its toe was extended between 1923 and 1924 to help better protect it. An earthquake on May 18, 1940, damaged the Project considerably, especially the Valley Division. Canals, levees and other features were damaged but repaired by late May. From 1936 through
World War II,
Civilian Conservation Corps workers, Indians from Mexico, Italian prisoners and German prisoners all worked to maintain the project. The Boulder Canyon Project Act in 1928 would signal change for the Yuma Project. The Act authorized the construction of the
Hoover Dam which curtailed flooding on the Colorado River but it also authorized the
All-American Canal and the
Imperial Dam. The Imperial Dam would serve as the lower Colorado's diversion dam and would also supply the Yuma Project with water. The dam was completed in 1938 and in 1941, the Bureau of Reclamation sealed off the Yuma Main Canal from the
Laguna Diversion Dam. All outlets from the Laguna Dam were sealed on June 23, 1948, allowing for full supply from the Imperial Dam. Becoming obsolete, the Bureau decommissioned the power plant at the Siphon Drop Spillway in 1972. ==Irrigation data==