Monday, April 25, 2016

Making the Cut: The Locks by the Numbers

Puget Sound Maritime researcher Joe Baar gives us some insights into the monumental undertaking that was and is the Ballard Locks. This is one of an occasional series of essays commemorating the centennial of the Ballard Locks and the Ship Canal.

Early, undated photo of the "government locks," probably mid-1940s. Puget Sound Maritime Historical Society, Joe Williamson Collection, Negative # 2301-4.

Early Efforts

By 1854 a navigable connection between Lake Washington and Puget Sound to allow movement of logs, milled lumber, and fishing vessels between these bodies of water was being discussed sporadically. After the Civil War, in 1867 the U.S. Navy endorsed a canal project, which included the idea of constructing a naval shipyard on Lake Washington. In 1891 the U.S. Army Corps of Engineers began planning the project; some preliminary work occurred in 1906.

Legal challenges mounted by Ballard mill owners who feared property damage and loss of waterfront in Salmon Bay, and by Lake Washington property owners whose docks and waterfront would be left 9 feet in the air, delayed construction for another five years. Work finally began after midsummer 1911 under Major Hiram M. Chittenden’s command. All the delays in planning and construction finally caused the Navy to establish the Puget Sound Naval Shipyard across Puget Sound from Seattle, in Bremerton.

To facilitate expected maritime traffic, three low bridges and trestles crossing the ship canal route were removed, at Fremont Avenue, Stone Way and Latona Avenue. New bridges in Ballard and Fremont were completed in 1917, followed by University Bridge in 1919, and Montlake Bridge in 1925. University Bridge was improved in 1932, and in 1934 the Corps declared the Lake Washington Ship Canal project complete.

Dates, Size, Usage

Construction began on the Government Locks August 6, 1911. Both locks opened to traffic in the summer of 1916, the small lock on July 30 and the large lock on August 3. During those four years and eleven months the U.S. Army Corps of Engineers excavated 1,661,400 cubic yards of earth for the Salmon Bay locks and dam alone, then filled the resulting basin with 227,000 cubic yards of carefully-formed concrete.

The Corps reported Hiram Chittenden Locks hosted 1,300,000 visitors and conveyed 50,000 watercraft and 1,000,000 tons of commercial goods during 2013. As the price of oil declines, we can expect even greater volumes in all these categories.

Comparison with Modern Structures

Modern comparisons show the relative size of this undertaking. Forty-five years after the locks first carried traffic, the Seattle Space Needle’s foundation was completed in 1961 using continuous 24-hour concrete placement into a mass requiring 2,747 cubic yards of concrete. In 2015 the Amazon Complex’s Block 19 Mat Pour, the building’s foundation within the block bordered by 6th and 7th Avenues and Lenora and Blanchard Streets, required more than 12,000 cubic yards, which covered the excavation’s bottom more than 12 feet deep in concrete and reinforcing steel. The volume of concrete used to construct the Government Locks amounts to about 19 times what the Amazon Block 19 Mat Pour required, and is about 83 times what the Space Needle’s 5,600-ton foundation used.

The Cuts - Fremont

A continuous waterway extending from Puget Sound to Lake Washington requires two separate and sequential channels excavated through intervening landforms. Westernmost of these is the Fremont Cut, named for the Fremont neighborhood lying just across a swale north of Queen Anne Hill. In 1883 the Lake Washington Improvement Company contracted with the Wa Chong Company to provide immigrant Chinese labor to dig the Fremont Cut along the low-lying route of Lake Union’s outlet, Ross Creek, to Salmon Bay, which was tidal salt water until the Government Locks were in place. After excavating this section in 1885 the Wa Chong laborers moved on to complete the log sluice at the Montlake Portage, located near and beneath today’s State Route 520. All this work was accomplished solely by use of hand tools.

The Fremont Cut’s eastern end near Fremont Avenue was separated from Lake Union by a low wooden dam, a small wooden lock, and a spillway. The cut thus continued Ross Creek’s function as an overflow drain for Lake Union and Lake Washington until the Government Locks at Salmon Bay were finished in 1916, which caused the water level behind them to rise and meet that of Lake Union. Shortly afterward Lake Washington drained westward until all the fresh-water bodies’ elevations equalized.

The Fremont Cut is approximately 5,800 feet long. The maintained ship channel taking up the center section of this waterway is 100 feet wide and 30 feet deep; the cut’s entire width, bank to bank, is 270 feet. The total amount of material excavated for this cut is thus around 2,200,000 cubic yards.

The Montlake Cut in snow, looking east, showing the remnants of the coffer dam, circa 1916. Puget Sound Maritime Historical Society, Joe Williamson Collection, Negative #10345.

The Cuts - Montlake

The easternmost cut at Montlake was originally named the Erickson Cut, after the first contractor hired to excavate this section. The Corps’ Major C.W. Kutz awarded C.J. Erickson’s contract on August 7, 1909, and dry excavation proceeded from October that year until October 26, 1910, when the dike on the Union Bay end of the cut was dynamited, allowing water to fill it. Further hydraulic excavation by Stilwell Brothers continued until June, 1914, and temporary wood cofferdams replaced part of the earthen dikes at both ends of the Montlake Cut to allow control of its water level so work on the Montlake Bridge’s abutments and foundations could proceed. After the last bond issue funding this construction passed in 1915, the bridge’s foundations were finally begun.

On August 26, 1916 the Portage Bay cofferdam was removed, followed several days later by the one on the Union Bay end. Lake Washington’s level then descended 8 feet 10 inches over the following three months, and the Lake Washington Ship Canal gradually assumed its normal level from Lake Washington, through Lake Union, to the Government Locks.

The Montlake Cut is approximately 2,500 feet long. The maintained ship channel taking up the center section is 100 feet wide and 30 feet deep; the excavation’s entire width between the high points of each bank, is 350 feet. The total amount of material excavated for this cut is nearly 2,400,000 cubic yards.

Observations from Today

The entire span of time between Thomas Mercer’s discussions with his fellow-citizens about what the inland lakes should be named, until the Corps of Engineers declared the Lake Washington Ship Canal complete, amounted to eighty years. Today we look forward with great impatience to the promised completion of several major public works projects, also related to transportation, in the central Puget Sound region. We are not able to calculate the cost of this new infrastructure with any real certainty, and discovering how much the Lake Washington Ship Canal actually cost the citizens, beginning 162 years ago until all the financing bonds were retired, is a task beyond the scope of this short article. What we do know from our own experience is, it wasn’t cheap then and it won’t be cheap now. These great expenses provide immense known and imagined benefits to all citizens for a very long time to come. Public works of this scale animate our society now and help bring the promise of a bright future for all of us.

Sources include the H.W. McCurdy Marine History of the Pacific Northwest; David Williams, Too High and Too Steep: Reshaping Seattle's Topography; Adam Wood, Images of America: The Ballard Locks; Sellen Construction Company, "Block 19 Mat Pour, October 4, 2014;

-- Joe Baar

Joe Baar has been fascinated with ships since his childhood on Brace Point. His lifelong avocation has included stints with the Sea Explorers, small boat school courtesy of the U.S. Army, working on yachts on Lake Union, and amassing a large collection of maritime books.


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