waterway, Seattle, Washington, U.S., 8 miles (13 km) long, with a minimum depth of 28.5 feet (8.7 metres), connecting Shilshole Bay (Puget Sound) with Lake Washington, passing through Lake Union, Portage Bay, and Union Bay. The canal was constructed between 1901 and 1911 in order to carry coal from mining districts east of Lake Washington to shipping points in Puget Sound. The locks near the west end of the canal, which overcome the difference of 26 feet (8 metres) between water levels, can accommodate ships up to 760 feet (230 metres) long; the locks are maintained by the U.S. Army Corps of Engineers. A fish ladder constructed in 1917 to accommodate anadromous fish in the region's waterways was replaced by a new structure—complete with a public viewing gallery—in 1976.