LOWELL CREEK DIVERSION TUNNEL
Lowell Canyon Rd. & Lowell Point Rd.
the Original Townsite of Seward was established in 1903, Lowell
Creek ran down what is now Jefferson Street. This is why Jefferson
Street is the widest right-of-way in Seward at 100 feet. Lowell
Creek is described as a short, flashy creek which rises in
the ice fields of the rugged Kenai Mountains. Almost since
the beginning of Seward until the Diversion Tunnel was constructed
in 1939, Lowell Creek produced from one to three severe floods
per year. During those floods large quantities of debris,
varying in size from small gravel to huge boulders, were carried
down what is now Jefferson Street to the delta from inexhaustible
supplies in the surrounding mountain canyons. The deposits
amounted to some 27,000 cubic yards annually (roughly 2,700
dump truck loads). On one occasion, in 1935, the stream deposited
10,000 cubic yards in 11 hours (roughly 1,000 dump truck loads).
These flood deposits on the delta caused periodic changes
in the channel through the town as the deposits elevated the
areas adjacent to the stream, and property suffered continuing
damage. It’s ironic that the same flooding that created
the land on which Seward was built, later threatened the location
and integrity of the original townsite.
In 1927 the Alaska Railroad Commission provided a small diversion
dam and a large timber flume to carry debris down Jefferson
Street and deposit it into Resurrection Bay. This flume, in
spite of heavy maintenance repairs, had so deteriorated by
1937 that it was beyond economical repair and constituted
a menace to the community. It was evident that a better designed,
relocated flood control project was necessary.
The Flood Control Project on Lowell Creek, or the Lowell
Creek Diversion Tunnel as it is generally known today, was
constructed to replace the 1927 flume. This historic flood
control project was the U.S. Corp of Engineers first completed
flood control project in Alaska, and it represents exemplary
engineering for the time and place. Construction began in
August 1939 and the project was complete in November 1940.
The Project consists of three parts:
1. The Diversion Dam;
2. The Tunnel; and
3. The Outlet.
The Diversion Dam is 400 feet long with a maximum height
of 25 feet. The Tunnel which runs through Bear Mountain, is
10 feet in diameter and 2,068 feet long. It is lined with
concrete, and the floor is armored with 40 pound railroad
rails. The outlet of the tunnel is located at the toe of Bear
Mountain. It is an open concrete flume 10 feet wide and about
109 feet long which, as we will see, discharges into Resurrection
Since construction of the diversion tunnel was completed
in 1940, the project has effectively controlled Lowell Creek
and its regular flooding. Despite severe damage to Seward
in the 1964 earthquake, the flood control project withstood
the massive earthshocks. Two years after the earthquake, in
1966, during one of the heaviest run-offs of record, Lowell
Creek rose to within two feet of the crest of the dam. In
the recent flood events of 1986 and 1995 the creek has been
within inches from the top of the dam.
Today, debris continues to be deposited at the outfall where
it naturally flushes out into the Bay.
when there is a flood event, the gravel, rock and other debris
comes in such quantities that the water can’t wash out
the debris fast enough and it builds up. It is during those
times that the City works on the east side (Bay side) of the
bridge and pushes the built up rock towards the bay.
The 60 year old tunnel, which has been owned by the City
of Seward since shortly after its construction, is in need
of significant repairs. The Corp of Engineers will be repairing
the tunnel this year.
Because of the amount and size of debris that flows down
Lowell Creek during flood events there is a justified concern
that debris could block the tunnel and cause it to fail. In
order to prepare for such an event the City is pursuing a
long term solution. Two different options have been identified
- construction of a second tunnel through Bear Mountain which
would be 10 feet wider than the current tunnel and cost approximately
30 million dollars. A second option is construction of a aquaduct
under Jefferson Street.