Hiram M. Chittenden Locks

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The Hiram M. Chittenden Locks are a complex of locks that sit in the middle of Salmon Bay, part of Seattle's Lake Washington Ship Canal. They are known locally as the Ballard Locks after the neighborhood to their north. (Magnolia lies to the south.)

The locks serve three purposes:

To maintain the water level of Lake Washington and Lake Union at 20.6 feet above Puget Sound's mean low tide.
To prevent the mixing of sea water from Puget Sound with the fresh water of the lakes (saltwater intrusion).
To move boats from the water level of the lakes to the water level of Puget Sound, and vice versa.

The complex includes two locks, a small (30 x 150 foot, 8.5 x 45.7 meter) and a large (80 x 825 foot, 24.4 x 251.5 meter). Using the small lock when boat traffic is low conserves fresh water during summer, when the lakes receive less inflow. Having two locks also allows one of the locks to be drained for maintenance without blocking all boat traffic (pictures of the drained large lock are located in the Canal lock article). It also includes a (235 foot, 71.6 meter) spillway with six (32 x 12 foot, 9.8 x 3.7 meter) gates to assist in water-level control, and a fish ladder is integrated into the locks for salmon migration.

The grounds feature a visitors center, as well as the Carl S. English, Jr., Botanical Gardens.

Operated by the U.S. Army Corps of Engineers, the locks were opened on July 4, 1917. They were named after U.S. Army Major Hiram Martin Chittenden, the Seattle District Engineer for the Corps of Engineers from April 1906 to September 1908. They were added to the National Register of Historic Places in 1978.