Part of the Lake Washington Ship Canal system, water flows into it from Lake Washington through the Montlake Cut, and out the Fremont Cut on its way to Puget Sound. Before construction of the canal, Lake Union emptied into Salmon Bay via a creek which followed roughly the same course as the Fremont Cut does today.
Because of the connection via the Hiram M. Chittenden Locks to the salt water of Puget Sound, there is some saline contamination, which worsens in the summer as the inflow rate from Lake Washington decreases and the locks open more frequently for pleasure craft.
Statistics:
Area of lake | 580 acres | 2.3 km² |
---|---|---|
Area of drainage basin | 384,000 acres | 1,554 km² |
Volume | 20,000 acre-feet | 25,000,000 cubic meters |
Depth (mean) | 34 feet | 10 m |
Depth (max) | 50 feet | 15 m |