Violent bandits often preyed upon the miners, such as the case of Jonathan R. Davis' killing of eleven bandits single-handedly. Camps spread out north and south of the American River and eastward into the Sierras. In a few years, nearly all of the independent miners were displaced as mines were purchased and run by mining companies, who then hired low-paid salaried miners. As gold became harder to find and more difficult to extract, individual prospectors gave way to paid work gangs, specialized skills, and mining machinery. Bigger mines, however, caused greater environmental damage. In the mountains, shaft mining predominated, producing large amounts of waste. Beginning in 1852, at the end of the '49 gold rush, through 1883, hydraulic mining was used. Despite huge profits being made, it fell into the hands of a few capitalists, displaced numerous miners, vast amounts of waste entered river systems, and did heavy ecological damage to the environment. Hydraulic mining ended when the public outcry over the destruction of farmlands led to the outlawing of this practice.