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.So basically, the Locks are a series of locks and gates and such that allow boats to pass through from Lake Washington/Union into Puget Sound. Since the water level in Puget Sound is remarkably higher than that of the lakes, the Locks act as an elevator of sorts to get the boats from one body of water to the other. Also at the Locks is the Fish Ladder.
The locks and associated facilities serve three purposes:
* To maintain the water level of the fresh water Lake Washington and Lake Union at 20–22 feet above sea level (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 fish ladder at the Chittenden locks is unusual—materials published by the federal government say "unique"—in being located where salt and fresh water meet. Normally, fish ladders are located entirely within fresh water.
When the Corps of Engineers first built the locks and dam, they changed the natural drainage route of Lake Washington. The locks and dam blocked all salmon runs out of the Cedar River watershed. (Pacific salmon are anadromous: they hatch in lakes, rivers, and streams—or, nowadays fish hatcheries—migrate to sea, and only at the end of their life return to fresh water to spawn.) To correct this problem, the Corps built a fish ladder as the locks were constructed to allow salmon to pass around the locks and dam.
The ladder was designed to use attraction water: fresh water flowing swiftly out the bottom of the fish ladder, in the direction opposite which anadromous fish migrate at the end of their lives. However, the attraction water from this first ladder was not effective. Instead, most salmon used the locks. This made them an easy target for predators; also, many were injured by hitting the walls and gates of the locks, or by hitting boat propellers.
The Corps rebuilt the fish ladder in 1976 by increasing the flow of attraction water and adding more weirs: most weirs are now one foot higher than the previous one. The old fish ladder had only 10 "steps"; the new one has 21, and a diffuser well mixes salt water in gradually through the last 10 weirs. As a part of the rebuilding, the Corps also added an underground chamber with a viewing gallery.The fish approaching the ladder smell the attraction water, recognizing the scent of Lake Washington and its tributaries. They enter the ladder, and either jump over each of the 21 weirs or swim though tunnel-like openings. They exit the ladder into the fresh water of Salmon Bay. They continue following the waterway to the lake, river, or stream where they were born.
While I was there, I got to see a few salmon go through the fish ladder. I also got to see them jumping up out of the water wildly in Puget Sound once they got out of the ladder :D Guess they were happy to be in the Sound ;)
Another part of the Locks area is a botanical garden, so I took a stroll through there as well :D
Here are some pics from my time there today:
WATCHING COHO SALMON PASS THROUGH THE FISH LADDER!