Water scarcity was felt starting in the 19th century, in the gold-mining era. The discovery of gold mines in the 1840s attracted a flood of immigrants to California. After a few years, many immigrants moved into agriculture, as it appeared to provide more stability than gold mining. The Central Valley had fertile soils, abundant water, and a flat gentle topography suitable for farming. An increase in demand for food eventually caused a shift from small-scale farming to large-scale intensive farming.