Ballard Locks, formally the Hiram M. Chittenden Locks, form Seattle’s seaward gateway between the Lake Washington Ship Canal and Puget Sound, linking the city’s freshwater lakes to salt water while controlling water levels. Conceived by 1854 and begun in 1911 after long delays, the system first passed a ship in 1916, and its opening permanently reshaped regional waterways when Lake Washington dropped 8.8 feet. The complex includes two locks, a spillway, and a fish ladder that was rebuilt in 1976 to improve salmon passage. Carrying the nation’s busiest lock traffic, it remains a heavily used engineering landmark and major visitor destination.