The EDCTC was designated as the Regional Transportation Planning Agency (RTPA) for El Dorado County on July 23, 1975. As the RTPA, the EDCTC serves as the planning and programming authority for transportation projects on the western slope of El Dorado County, excluding those areas within the Tahoe Regional Planning Agency boundaries. In 2008, the EDCTC was designated as the Airport Land Use Commission for the Placerville, Georgetown, and Cameron Park Airports. The EDCTC also manages the Freeway Service Patrol for US Highway 50 in El Dorado County. The EDCTC is responsible for coordinating regional transportation planning for the western slope of El Dorado County. Being the State-mandated Regional Transportation Planning Agency, EDCTC prepares the Regional Transportation Plan and Improvement Program for the Western Slope.