Hiram M. Chittenden Locks

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Chittenden Locks and Lake Washington Ship Canal
An aerial view of the locks, facing west
Location Salmon Bay, Seattle, Washington
Built 1906
Architect Multiple
Architectural style Late 19th And 20th Century Revivals, Other
Governing body Army Corps of Engineers
NRHP Reference # 78002751[1]
Added to NRHP December 14, 1978

The Hiram M. Chittenden Locks, or Ballard Locks, is a complex of locks at the west end of Salmon Bay, in Seattle, Washington's Lake Washington Ship Canal, between the neighborhoods of Ballard to the north and Magnolia to the south.[2]:2[3][4]:6

The Ballard Locks carry more boat traffic than any other lock in the US, and the Locks, along with the fish ladder and the surrounding Carl S. English, Jr., Botanical Gardens attract more than one million visitors annually, making it one of Seattle's top tourist attractions.[5]:7–8 The construction of the locks profoundly reshaped the topography of Seattle and the surrounding area, lowering the water level of Lake Washington and Lake Union by 8 feet (2.4 m), adding miles of new waterfront land, reversing the flow of rivers, and leaving piers in the eastern half of Salmon Bay high and dry.[5]

Prior to construction[edit]

1854 Thomas Mercer proposes connecting lakes Union and Washington to Puget Sound
1860 Landowner Harvey L. Pike tries to dig a ditch, by himself, to transport logs between Portage Bay and Union Bay
1871 Pike, Thomas Burke and Daniel Gilman incorporate the Lake Washington Canal Company, but company builds a coal-carrying tramway, rather than a canal
1883 David Denny and Thomas Burke hire Chinese laborers to dig Portage Canal, a 16-foot (4.9 m) channel with a lock, suitable for floating logs
1880s A canal is dug from Lake Union to Salmon Bay, with a wooden lock near Fremont
1893 Eugene Semple attempts to build a canal across the southern end of Beacon Hill and fill the south Elliott Bay tidelands, what is Harbor Island today
1900 Washington State Legislature endorses northern route, through Lake Union
1901 Due to delays, planned freshwater Navy base on Lake Washington scrapped in favor of Navy Yard in Bremerton
1902 Army Corps of Engineers rejects Semple's Canal route. Rivers and Harbors Act appropriates funds and assigns 3 officers to study possible canal in Seattle
1904 After financing dries up and Semple resigns, work on Beacon Hill canal stops, though filled tidelands are useful
1906 Entrepreneur James A. Moore wins Congressional approval for private canal project from Salmon Bay to Shilshole
April 1906 Hiram M. Chittenden arrives as new Corps of Engineers Seattle District Commander, supporting Moore's canal route but criticizing his plans as too modest and underfunded
1908 Chittenden retires but continues to lobby Congress for Ballard Locks
1910 Congress appropriates $2,275,000 for locks, though King County is responsible for rest of canal
1916 Temporary dam at Montlake is breached.
May 8, 1917 Government Locks, as the Ballard Locks are called, opens for boat traffic
1956 Government Locks renamed in memory of Chittenden (d. 1917)

For centuries, people had been dragging boats between the lakes, giving names like "carry a canoe" sxWátSadweehL to the crossing points.[6] In 1854 Thomas Mercer proposed canals connecting Lake Union and Lake Washington to Puget Sound in a speech at the first Independence Day celebration of the Seattle area's first permanent white settlement, shortly after its founding. Mercer gave the lakes the names they are presently called, over the original Lushootseed names used by the Duwamish, tenas Chuck or XáXu7cHoo ("small great-amount-of-water") for Lake Union and hyas Chuck or Xacuabš ("great-amount-of-water") for Lake Washington. Lake Union was chosen to suggest the future canals merging the waters, and Lake Washington for George Washington.[7][6][8]

Proposed canal routes included the Black River, Semple's Canal across Beacon Hill, two possible routes from Lake Union to Elliott Bay via Lower Queen Anne and Belltown, the Montlake Cut, and Salmon Bay to Smith Cove via Interbay.

In 1860 local landowner Harvey L. Pike tried to dig a ditch by himself with pick and shovel at Montlake to transport logs between Portage Bay and Union Bay, in the hopes of increasing the value of his property along the route.[9] Giving up on digging the first Portage Canal himself, in 1871 he joined Thomas Burke and Daniel Gilman in incorporating the Lake Washington Canal Company, deeding his land to the company. Instead of finishing the canal, the company instead built a tramway to carry coal brought by barge across Lake Washington.[9] In 1883, David Denny and Burke hired a crew of Chinese laborers to complete the canal at Montlake, creating a 16-foot (4.9 m) channel that included a lock, capable of floating logs down from Lake Washington to Lake Union.[9]

In the Rivers and Harbors Act of 1902, Congress directed the Secretary of War to appoint a committee of three officers to study the feasibility of a canal and lock system to connect Puget Sound to Lake Washington. Lieutenant Colonel William H. Heuer, Captain William C. Langfitt and Lieutenant Robert P. Johnson met August, 1902 in Seattle and conducted a survey of possible routes.[10] They examined the route of the Lake Washington Waterway Company, via Shilshole, as well as a route from Lake Union to Smith Cove, the Montlake coal tramway, and Thomas Mercer's farm. In November 1902, a public meeting was called in the Chamber of Commerce hall, but was quickly adjourned because no one came to speak.[10]


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 (6.1–6.7 m) above sea level, or more specifically, 20.6 ft (6.3 m) above Puget Sound's mean low tide.[2]:2[3][5]:8
  • To prevent the mixing of sea water from Puget Sound with the fresh water of the lakes (saltwater intrusion).[2]:2–3
  • To move boats from the water level of the lakes to the water level of Puget Sound, and vice versa.[2]:3

The complex includes two locks, 30 ft × 150 ft (9.1 m × 45.7 m) (small) and 80 ft × 825 ft (24 m × 251 m) (large).[2]:8 The complex also includes a 235 ft (72 m) spillway with six 32 ft × 12 ft (9.8 m × 3.7 m) gates to assist in water-level control.[2]:8 A fish ladder is integrated into the locks for migration of anadromous fish, notably salmon.[2]:3[11]

The grounds feature a visitors center,[2]:4 as well as the Carl S. English, Jr., Botanical Gardens.[2]:5

Operated by the US Army Corps of Engineers,[12] the locks were formally opened on July 4, 1917,[13] although the first ship passed on August 3, 1916.[14] They were named after US Army Major Hiram M. Chittenden, the Seattle District Engineer for the Corps of Engineers from April 1906 to September 1908.[2]:4 They were added to the National Register of Historic Places in 1978.[1]

How the Chittenden Locks work.jpg

Vessels passing from the freshwater Lakes Washington and Union to Puget Sound enter the lock chamber through the open upper gates (A in the accompanying diagram). The lower gates (B) and the draining valve (D) are closed. The vessel is assisted by the lockwall attendants who assure it is tied down and ready for the chamber to be drained.[2]:2

Next, the upper gates (A) and the filling valve (C) are closed and the draining valve (D) is opened allowing water to drain via gravity out to Puget Sound.[2]:2

When the water pressure is equal on both sides of the gate, the lower gates (B) are opened, allowing the vessels to leave the lock chamber.[2]:2

The process is reversed for upstream locking.[2]:2


The Chittenden Locks shortly after their construction. The Carl P. English Gardens had not yet been started. The inset shows the nearby Fishermen's Terminal.

The complex includes two locks.[2]:8 Using the small lock when boat traffic is low conserves fresh water during summer, when the lakes receive less inflow. Having two locks also allows one of the locks to be drained for maintenance without blocking all boat traffic. The large lock is drained for approximately 2-weeks, usually in November, and the small lock is drained for about the same period, usually in March.

A worker cleaning the small lock during annual maintenance. Drying out the chambers allows inspection and repair. After cleaning, the walls are painted.[15]

The locks can elevate a 760-by-80-foot (232 m × 24 m) vessel 26 ft (7.9 m), from the level of Puget Sound at a very low tide to the level of freshwater Salmon Bay, in 10–15 minutes. The locks handle both pleasure boats and commercial vessels, ranging from kayaks to fishing boats returning from the Bering Sea to cargo ships. Over 1 million tons of cargo, fuel, building materials, and seafood products pass through the locks each year.[4]:6



South of the small lock is a spillway dam with tainter gates used to regulate the freshwater levels of the ship canal and lakes. The gates on the dam release or store water to maintain the lake within a 2 ft (0.61 m) range of 20 to 22 ft (6.1 to 6.7 m) above sea level. Maintaining this lake level is necessary for floating bridges, mooring facilities, and vessel clearances under bridges.[2]:2

The locks and the adjacent Commodore Park

"Smolt flumes" in the spillway help young salmon to pass safely downstream.[4]:8 Higher water levels are maintained in the summer to accommodate recreation as well as to allow the lakes to act as a water storage basin in anticipation of drought conditions.[2]:2

Salt water barrier[edit]

If excessive salt water were allowed to migrate into Salmon Bay, the salt could eventually damage the freshwater ecosystem. To prevent this, a basin was dredged just above (east of) the large lock. The heavier salt water settles into the basin and drains through a pipe discharging downstream of the locks area. In 1975, the saltwater drain was modified to divert some salt water from the basin to the fish ladder, where it is added via a diffuser to the fish ladder attraction water; see below.[2]:2

To further restrict saltwater intrusion, in 1966, a hinged barrier was installed just upstream of the large lock. This hollow metal barrier is filled with air to remain in the upright position, blocking the heavier salt water. When necessary to accommodate deep-draft vessels, the barrier is flooded and sinks to the bottom of the chamber.[2]:3

Fish ladder[edit]

Attraction water is visible in two places in this photo; the lower part of the fish ladder snakes around the diffuser well.
Fish ladder viewing room.
View from above of the part of the fish ladder over the viewing room.

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.[11]:2

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. 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. 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.[11]:2

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.[11]:2

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. A diffuser well mixes salt water gradually into the last 10 weirs. As a part of the rebuilding, the Corps also added an underground chamber with a viewing gallery.[4]:8[11]:2, 6

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. Once there, the females lay eggs, which the males fertilize. Most salmon die shortly after spawning.[11]:2–3

The offspring remain in the fresh water until they are ready to migrate to the ocean as smolts. In a few years, the surviving adults return, climb the fish ladder, and reach their spawning ground to continue the life cycle.[11]:3 Of the millions of young fish born, only a relative few survive to adulthood. Causes of death include natural predators, commercial and sport fishing, disease, low stream flows, poor water quality, flooding, and concentrated developments along streams and lakes.[11]:4

Visitors to the locks can observe the salmon through windows as they progress along their route. Although the viewing area is open year-round, the "peak" viewing time is during spawning season, from about the beginning of July through mid-August. A public art work, commissioned by the Seattle Arts Commission, provides literary interpretation of the experience through recordings of Seattle poet Judith Roche's "Salmon Suite," a sequence of five poems tied to the annual migratory sequence of the fish.

The fish ladder in profile. The actual fish ladder makes several right angle turns, which are not reflected in this diagram. The pamphlet shows the height of each weir. The last three weirs are adjustable to the level of Salmon Bay. Salt water is mixed with fresh water by the diffuser well in weirs indicated here by a darker gray. The longest weir in the ladder is for the viewing window.[11]:6

Migratory fish[edit]

Among the species of salmonids migrating routinely through the ladder at the Chittenden Locks are Chinook (king) salmon (Oncorhynchus tshawytscha), Coho (silver) salmon (Oncorhynchus kisutch), Sockeye (red) salmon (Oncorhynchus nerka), and steelhead (Oncorhynchus mykiss).[2]:5–6

Seattle salmon-run viewing schedule at the Seattle Fish Ladder. Sockeye – June, July; Chinook and Coho – Sept, Oct; steelhead – late fall and winter


The cover of the US government pamphlet "Lake Washington Ship Canal Fish Ladder" depicts the fish ladder at the locks.
  1. ^ a b "National Register Information System". National Register of Historic Places. National Park Service. 2007-01-23. 
  2. ^ a b c d e f g h i j k l m n o p q r s t "Lake Washington Ship Canal and Hiram M. Chittenden Locks" (pamphlet), US Government Printing Office: 1999-791-887. As work of the Federal Government, this document is in the public domain, and some of the wording in this article is almost verbatim from the pamphlet.
  3. ^ a b "Ballard Locks". CityOfSeattle.net. Retrieved September 21, 2007. 
  4. ^ a b c d "Lake Washington Ship Canal: Hiram M. Chittenden Locks" (pamphlet), US Army Corps of Engineers, 2006. As work of the Federal Government, this document is in the public domain, and some of the wording in this article is almost verbatim from the pamphlet.
  5. ^ a b c Woog, Adam (2008), Images of America; The Ballard Locks, Arcadia Publishing, ISBN 9780738559179 
  6. ^ a b Thrush, Coll-Peter (2009), Native Seattle: Histories from the Crossing-Over Place, University of Washington Press, ISBN 978-0-295-98812-2 
  7. ^ Crowley, Walt (July 1, 1999), "Seattle residents celebrate July 4, 1854, and adopt names for Lake Union and Lake Washington", HistoryLink.org, retrieved July 27, 2015 
  8. ^ Crowley, Walt (July 1, 1999), "Lake Washington Ship Canal", HistoryLink.org 
  9. ^ a b c Long, Priscilla (June 24, 2001), "Harvey Pike starts to dig a canal connecting Seattle's Union and Portage bays in 1860", HistoryLink.org, retrieved July 27, 2015 
  10. ^ a b Office of Chief Engineers (January 27, 1903), Report of a Board of Engineers upon the feasibility and advisability of constructing a canal with necessary locks and dams, connecting Puget Sound with Lakes Union and Washington, of sufficient width and depth to accommodate the largest commercial and Naval vessels, with plans and estimates of cost thereof, United States Army, pp. 2340– 
  11. ^ a b c d e f g h i "The Lake Washington Ship Canal Fish Ladder" (pamphlet), US Government Printing Office: 1996-792-501. As work of the Federal Government, this document is in the public domain, and some of the wording in this article is almost verbatim from the pamphlet.
  12. ^ Sherrill Mausshardt and Glen Singleton, "Mitigating Salt-Water Intrusion through Hiram M. Chittenden Locks", Journal of Waterway, Port, Coastal and Ocean Engineering, Vol. 121, No. 4, July/August 1995, pp. 224-227 , (doi 10.1061/(ASCE)0733-950X(1995)121:4(224)). Abstract on site of American Society of Civil Engineers mentions that the locks are operated by the Corps. Accessed 21 September 2007.
  13. ^ Walt Crowley, Turning Point 11: Borne on 4 July: The Saga of the Lake Washington Ship Canal, HistoryLink.org Essay 3425, July 3, 2001. Accessed 21 September 2007.
  14. ^ Gordy Holt, Short Trips: Fascinating history sets the stage for a Ballard Locks outing, Seattle Post-Intelligencer, Last updated August 15, 2007. Accessed 21 September 2007.
  15. ^ "Chittenden Locks small chamber closing 12 days for annual maintenance (press release)" (Press release). US Army Corps of Engineers, Seattle District. March 9, 2012. Retrieved March 16, 2012. 

External links[edit]

Coordinates: 47°39′55.68″N 122°23′49.56″W / 47.6654667°N 122.3971000°W / 47.6654667; -122.3971000