Water tunnels are tunnels (below-ground channels) used to transport water to areas with large populations or agriculture. They are frequently part of aqueducts. Some aqueducts, such as the Delaware Aqueduct are single long tunnels. In other cases, such as the San Jacinto tunnel on the Colorado River Aqueduct, water tunnels form parts of far longer aqueducts. In cases where the outflow of a water tunnel is into an existing stream or river flowing to the point of water use, the term aqueduct is less likely to be used, as with the Harold D. Roberts Tunnel from Dillon Reservoir to the North Fork South Platte River.
Notable water tunnels, or systems including water tunnels