Hiram M. Chittenden Locks (Seattle) - the Ballard large lock on the Lake Washington Ship Canal is currently drained for cleaning and repair. These locks were opened in 1917 and are reported to be the busiest in the US (the Freemont Bridge in Seattle is the most opening draw bridge in the world - opening on an average every 15 minutes). The Ballard Locks connect Lake Union - Salmon Bay (fresh water) which is about 20' - 22' higher than Puget Sound (salt water). The large lock is 80' wide and 825' long - for every foot of lift (or drop) - 500,000 gallons of water moves in or out of the lock chamber. To get an idea on how big this lock is look at the Bob-Cat front loader at the far end of the lock near the gate.