The Hiram M Chittenden Locks is one the favorite spots of tourists and Seattle residents alike to watch boats entering the locks and also wildlife in the area. Operated by the US Army Corps of Engineers, the lock complex was the largest navigation facility in North America when it was dedicated on 4th July, 1917. Today, it continues to allow both commercial vessels and recreational boats to pass between the freshwater of Lake Washington, Lake Union, and Salmon Bay, and the saltwater of Puget Sound.
Also known as the Ballard locks as it is situated in the Ballard neighborhood in Seattle, the complex includes two locks, a small (30 x 150 ft, 8.5 x 45.7 meter) and a large (80 x 825, 24.4 x 251.5 meter). In a typical year, the lock is responsible for more than a million tons of cargo traveling to the docks and warehouses of Seattle’s harbor.
Depending on the tides, there can be 6-26 feet difference between the saltwater Puget Sound and the freshwater lakes. Hence to pass from the lake to Puget Sound or vice versa, a vessel has to enter the lock.
Here the small lock acts as an elevator while the saltwater is drained and the lock is filled with freshwater. Once the water reaches the same level as the lake, the gate is opened and the vessels move on.
The same process is reversed when vessels move from the lake the Sound. It takes 10-15 minutes and about 7.5m gallons of freshwater to fill the large lock. The locks also play an important role in preventing saltwater intrusion into the fresh water of the lakes. Salt intrusion could result in serious damage to the freshwater ecosystems of Lake Washington and its tributaries.
A nearby spillway dam regulates the water levels of the canals and lakes. This allows for higher levels in the summer for recreational uses and to prepare for potential droughts.
As the locks sits on the migration path of the Pacific salmon and steelhead heading upstream to spawn, a fish ladder was built to allow the fish to bypass the locks. These mature salmon are returning to the creek, river, hatchery etc where their journey had begun 3-5 years ago. There they will spawn and die. (refer to Issaquah Salmon Hatchery )The fish ladder has 21 steps or “weirs” which allows spawning fish to climb to the freshwater side. Young fish, or “smolts” then return down through the locks out to Puget Sound in spring. The fish ladder and the viewing gallery is currently closed for repairs till next year.
Apart from salmon, harbors and sea birds are a common sight here.