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Due to construction of Lake Washington Ship Canal, Lake Washington is lowered 8.8 feet beginning on August 25, 1916, and the Black River disappears.
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on August 25, 1916, Lake Washington is lowered 8.8 feet, due to construction of
the Lake Washington Ship Canal, and the Black River disappears. The ship canal
is being built between Lake Washington and Puget Sound. Because of the
different water levels in Lake Washington, Lake Union, Salmon Bay, and
Shilshole Bay, the federal government builds a double lock at Ballard and
lowers Lake Washington to the same height as Lake Union, from about 30 feet
above mean lower low water (the average of each day's lowest low tide) on
Shilshole Bay to 21 feet. The level of Salmon Bay is raised to 21 feet behind
the locks and dam at its mouth. The lowering of Lake Washington and raising of
Salmon Bay causes a number of changes to the watershed, most dramatically the
drying up of the Black River, which had been the lake's outlet, when the lake's
water level drops below that of the river-channel entrance at its south end. As
a result, the way water moves through the watershed changes drastically, with
environmental and human consequences.
Reshaping the Watershed
The U.S. Army Corps of Engineers began
construction of the Lake Washington Ship Canal in 1911. It was the last of
several attempts to build a transportation route around the hills between Lake
Washington and Seattle to promote trade and development. Two land barriers and an
elevation differential of about 30 feet block the water route between Lake Washington, Lake Union, and Puget Sound. Major Hiram M. Chittenden (1858-1917), of the corps, finalizes a plan
to build a canal between Shilshole Bay, on Puget Sound, and Lake Washington,
passing through Salmon Bay to Lake Union, then on to Lake Washington. One lock,
at the west end at Ballard, will help boats negotiate the drop in elevation
between Salmon Bay and Puget Sound. Instead of a lock between Lake Washington and
Lake Union, the Corps cuts a canal and drains Lake Washington down to the same
level as Lake Union, 8.8 feet lower than its average level.
It takes about three months to drain down and
cause radical changes in the hydrological systems of the Green-Duwamish River
watershed. As a result of the lowering of the lake, a new watershed will form,
a saltwater inlet will become a freshwater bay, and the way water moves through
the lakes and rivers will be different.
The Environment Before
Before the construction of the ship canal,
the drainage of the Lake Sammamish, the Sammamish River, Lake Washington, and
the Black River were part of the Green-Duwamish River watershed. Lake Sammamish
was fed by a number of streams that drained the surrounding land. Its
outlet, the Sammamish Slough (also known as the Sammamish River), was the
main source of water into Lake Washington, though that lake was also fed by creeks
and springs along its perimeter. The Black River, on the lake's south end at
Renton, drained Lake Washington. The Black River was joined by the Cedar River just a half
mile downstream from the lake. The Black River joined with the Green River at
what is now Tukwila to form the Duwamish River. Before 1906, the White River
also drained into the Duwamish, but its channel shifted during a flood so that it flowed southward to become
a tributary of the Puyallup River, which drained into Commencement Bay at Tacoma.
The whole Lake Sammamish, Lake Washington,
and Black River system moved relatively slowly. Coastal geologist Michael Chrzastowski
estimated that water stayed in Lake Washington for about five years before
entering the Black River and continuing on to the sea. The slough between the
two lakes was marshy, with a broad, meandering channel. The Black River crossed
the slowly, but continually, rising Cedar River alluvial fan. As the fan built
up over several thousand years, the level of Lake Washington also rose.
By the 1900s, the lake was about 30 feet above
mean lower low water on Puget Sound at Shilshole Bay. This was its average
level; seasonal changes in precipitation could cause the shoreline of the lake to
vary by as much as seven feet. During exceptionally rainy periods the Black River flowed
in two directions: downstream to the Duwamish and upstream, back into the lake.
These fluctuation water levels created many marshy areas along the lakeshore.
When American settlers began establishing
farms along the Duwamish and Black rivers, they were plagued by floods. Though
the rivers' height only varied by three to four feet, it still hindered
settlement and development. In an attempt to get the river moving more quickly
and draining the lake more effectively, the settlers tried some dredging and debris
clearing. It did speed up the river and reduce backflow from the Black back
into the lake, but did not solve the problem.
The rest of the ship canal route was separate
from the Green-Duwamish basin. Lake Union was fed by streams and springs along
its shores and drained through a small creek known by several names -- Ross
Creek, Shilshole Creek, the Outlet -- to Salmon Bay. The lake level was 21 feet
above the mean lower low water at the bay. It fluctuated very little because
the area of land that drained into the lake was relatively small.
Before the closing of the locks at Ballard in
July 1916, Salmon Bay was a saltwater inlet of Shilshole Bay on Puget Sound. It
fluctuated with the tides each day. At low tide it was a very shallow channel, about
three feet deep. At the highest tides, it reached a depth of about 15 feet.
Building the Ship Canal
Work on the Lake Washington Ship Canal began
in 1911. By July 1916 the locks at the western end of Salmon Bay were ready to
be closed. After the locks were closed, Salmon Bay slowly rose to the level of
Lake Union. Saltwater was kept, as much as possible, on the west side (the Puget Sound side) of
the locks. Lake Union continued to drain along the same route, but the creek was replaced with a canal cut through the surrounding land.
Work proceeded on the strip of land, then called Montlake Portage, that separated Lake Washington and Lake Union. A canal, to be called Montlake Cut, was dug through this land. On August 25, 1916, the cofferdam holding Lake
Union back from the canal was opened
and water gushed into it. Within a few days, the cofferdam on the east
(Lake Washington) end of the cut was opened and Lake Washington joined with Lake Union. Over the
next three months, the level of Lake Washington dropped 8.8 feet. Wetlands
along the shore drained and the lake dropped below the level of the Black River channel. The Lake Washington Ship Canal became the new outlet for Lake Washington.
A couple of years earlier, Renton residents
had diverted the Cedar River from its channel through town that repeatedly and
destructively flooded to a new channel that led to Lake Washington. According
to Morda C. Slauson, a Renton historian, the spring runs of salmon arrived just
in time to be trapped by the receding waters. In the 1930s, new salmon stock
would be introduced via the ship canal, but the Black and Cedar river runs
A New Watershed
Water moved differently through the new
watershed. It passed through Lake Washington much more quickly, in about two
years. The steeper gradient created by the lowered lake level on Lake
Washington caused the Sammamish Slough current to move more quickly, increasing
the channelization of the waterway (making a deeper channel).
At the same time, the changes drastically
reduced the volume of water flowing through the Duwamish River. It reduced--but
did not eliminate--flooding, and allowed farmers to drain and cultivate more
land. Before long, much of the lower Duwamish would be straightened and dredged
into a waterway to facilitate economic development. This, along with filling on
the Seattle tidelands, led to a dramatic loss of the Duwamish estuary. Much of
the industrial area of Seattle is built on top of the filled Duwamish estuary.
Benefits and Losses
Though the ship canal would bring
many economic and social benefits to Seattle, its construction did have some
detrimental effects. In the simplest sense, the city lost something beautiful. Clarence Dullahaut, who moved to Renton in 1903,
described the Black River in an interview: "It was a pretty river,
meandering along. People used to come up the Duwamish from the Sound up the
Black to Lake Washington in launches" (Sato, 56).
The Duwamish tribe had a village located
along the Black River for at least 1,400 years and perhaps for thousands of
years and members of the tribe lived along the river. Members of area Indian tribes who had long
gathered resources from those wetland areas and who relied on salmon as a
foundation of their diet and as an integral part of their spiritual beliefs,
lost access to those resources on Lake Washington and along the Black River.
The right to fish and gather plant materials had been retained in the treaties
the tribes signed with the United States, but it became difficult to exercise
those rights in the much reduced environment that resulted from the
There was also an emotional loss for the
Duwamish. Tribal member Joseph Moses stated in an interview with David Buerge,
"That was quite a day for the white people at least. The waters just went
down, down, until our landing and canoes stood dry and there was no Black River
at all. There were pools, of course, and the struggling fish trapped in them.
People came from miles around, laughing and hollering and stuffing fish into
gunny sacks" (Sato, 57). According to Morda C. Slauson, a historian in
Renton, Henry Moses (1900-1969) "dragged his canoe out of the mud and said
he never wanted to paddle it again" (Slauson, 5).
Like many large civil engineering projects in Seattle, the
Lake Washington Ship Canal wrought enormous change to the landscape and to the
lives of people who lived on the waterways affected by the project. It brought
many benefits to the city, but exacted a large environmental and social price.
Michael J. Chrzastowski, M. Historical
Changes to Lake Washington and Route of the Lake Washington Ship Canal, King
County, WA, U.S. (Reston, Va.: U.S. Dept. of the Interior, Geological
Survey, 1983); Mike Sato, The Price of Taming a River:
The Decline of Puget Sound's Duwamish/Green Waterway (Seattle: The
Mountaineers, 1997), 51-57; Morda C. Slauson, "'Where the Black River
Flowed,'" April 1967, typescript manuscript, Renton Historical Society; "Wedding of Lake Union and Lake Washington Celebrated by Crowd," The Seattle Times, August 26, 1916, p. 12.
Note: This essay replaces an earlier essay on the same subject. It was corrected on August 9, 2016, to state that the Montlake Cut was first opened on August 25 (not 26), 1916.
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Water gushes from Lake Union into Montlake Cut, Seattle, August 25, 1916
Courtesy MOHAI (Image No, 1983.10.10325)
Lake Washington Ship Canal, eastern half
Map by Chris Goodman
Lake Washington Ship Canal (western half) with Hiram M. Chittenden locks, Seattle
Map by Chris Goodman
Tidal channel linking Salmon Bay and Shilshole Bay before construction of Lake Washington Ship Canal, Seattle, ca. 1900
Photo by Anders Beer Wilse, Courtesy MOHAI (Image No. 1988.33.33)
Indians camping near the Black River, near Renton, ca. 1893
Photo by Carrie Coe
Black River, near Renton, 1900s
Canoeing on the Black River, ca. 1910
Black River after Lake Washington was lowered 8.8 feet, near Renton, 1916
Courtesy Renton Historical Society (Neg. No. 3866)