El Dorado County is a county located in the historic Gold Country in the Sierra Nevada Mountains and foothills of eastern California. The 2004 population was estimated to be 172,889, its 2000 population was 156,299. The El Dorado county seat is in Placerville. The population of El Dorado County has grown as the Greater Sacramento has expanded into the region. In the unique Lake Tahoe area of the county, since hosting the 1960 Winter Olympics brought it to attention, the population and environmental protection has grown also. El Dorado Transit runs local service in Placerville and surrounding areas.