capital in 1854. As the economy of the Sacramento Valley grew, the Southern Pacific Railroad established tracks along the river to connect California with Oregon following the ancient path of the Siskiyou Trail, in the 1880s and 1890s. Many parts of the railroad were treacherous, especially in the mountainous areas north of Dunsmuir. It was not long after Sacramento surpassed a population of 10,000, then the Great Flood of 1862 swept away much of it (and almost everything else along the Sacramento River) and put the rest under water. The flood waters were exacerbated by the sediments washed down by the millions of tons by hydraulic mining, which filled the beds of the Sacramento, Feather and American rivers up to in Sacramento and also covered thousands of acres of Central Valley lands. A flood in 1875 covered the city of Marysville and when it subsided the town's streets were filled with debris and rocks washed down from the "hydraulicking" going on upstream. Repeated floods and increased demand for Sacramento River water saw a plethora of massive changes to the environment beginning in the 20th century. An early project was undertaken to raise the entire city of Sacramento about above its original elevation. This was followed by much bigger engineering projects to control and store the floodwaters of the Sacramento River; the building of these public works would radically transform the river during the 20th century. Dams and water use From the late 19th century through the 20th century, California experienced an economic boom that led to the rapid expansion of both agriculture and urban areas. The Central Valley was becoming a heavily developed irrigation farming region, and cities along the state's Pacific coast and the Sacramento and San Joaquin rivers were growing rapidly, requiring river control to prevent flooding on the one hand, and to ensure a consistent supply of water on the other. The U.S. Army Corps of Engineers and the State of California completed reports as early as the 1870s and 1880s which outlined future development of the Sacramento, Feather, Yuba and Bear rivers. In 1873, Colonel B.S. Alexander of the Army Corps of Engineers surveyed the Central Valley's hydrology and irrigation systems and proposed a great network of pumps and canals that would take water from the Sacramento River in the north, and transport it to drought-prone central and southern California, especially the San Joaquin Valley. The