On October 27, 1909, hundreds of people gather to watch the beginning of the excavation for the Lake Washington Ship Canal. The event takes place at the isthmus between Union Bay and Portage Bay. Following speeches by dignitaries, former governor John H. McGraw (1850-1910) pulls the throttle on a steam shovel to begin digging the Montlake Cut, which will replace a much smaller cut that had been excavated between Lake Washington and Lake Union in 1884-1885.
In August 1911, work began on the Hiram M. Chittenden Locks with the construction of a cofferdam, or temporary structure, built to keep water out of the site where the locks will be built. (The locks, originally known as the Government Locks, were renamed in 1956 to honor Hiram Chittenden [1858-1917], who had been in charge of the Seattle District of the Army Corps of Engineers and was the person responsible for funding and design.)
The cofferdam was finished one year later. By November 1914, most of the concrete work on the locks was completed.
On February 2, 1916, the gates of the locks were opened all the way, and work began on the permanent overflow dam to the south of the locks. It was completed by July and on July 12 the gates of the locks were closed and Salmon Bay started to be filled with freshwater. On August 3, 1916, boats were allowed to pass from Puget Sound through the locks into Salmon Bay. By the official opening on July 4, 1917, more than 16,000 vessels had locked through more than 300,000 tons of goods ranging from logs to hay to coal.
King County was responsible for excavating the cuts between Lake Washington and Lake Union and between Lake Union and Salmon Bay. Major James B. Cavanaugh (1869-1927), who had taken over the Seattle District, U.S. Army Corps of Engineers, in 1911, supervised the construction project.
When completed, the canal and locks connected Puget Sound to Lake Union and Lake Washington.