The Lake Chelan Hydroelectric Project is located approximately
32 miles north of the city of Wenatchee in Chelan County, near
the geographic center of Washington state.
The dam is at the lower, or southeasterly end of 50.4-mile-long
Lake Chelan, adjacent to the city of Chelan. The Powerhouse is
located near the community of Chelan Falls.
facts about the Lake Chelan Hydro Project:
- 2 generators.
- Generator nameplate capacity is 59 megawatts.
- Dam contains 8 spillway gates.
- Original construction completed in 1927.
- Project license expires in 2056.
The Chelan River has a long, colorful history of dam
development for navigation, water supply, and power generation.
The first dam built to raise the level of Lake Chelan was
completed in 1892. It was constructed to provide water for
south Chelan real estate and navigation to the city of Chelan.
It washed out during June of that year, only to be replaced by
another structure built by the newly formed Chelan Water Power
Company in 1893. This much larger and stronger dam was designed
to raise the lake level enough to allow steamships to land at
Chelan. However, even this structure lasted only a year before
falling victim to a massive flood in June 1894. In early 1899,
M.M. Kingman purchased the Chelan Water Power Company and
proceeded to build another dam, this time for power generation.
The "turning on of lights" was celebrated in Chelan
in May 1903. The Chelan Water Power Company was purchased by
the Chelan Electric Company in 1906. That firm was then
purchased by Spokane-based Washington Water Power Company in
1925. A year later, Washington Water Power received a 50-year
federal license to construct the existing dam and powerhouse.
The first generating unit was placed in commercial operation in
September 1927, followed by the second unit 11 months later.
The dam is a steel-reinforced concrete gravity structure. It is
approximately 40 feet high and 490 feet long. It contains eight
spillway bays. When the spillway gates are open, water is
discharged down the normally dry Chelan River channel.
The Power Tunnel
Water to power the turbine generators is delivered through an
underground penstock connecting the dam and the powerhouse. It
delivers water from the dam at the southeasterly end of Lake
Chelan to the powerhouse at Chelan Falls, a vertical drop of
nearly 350 feet. This steel and concrete tunnel is
approximately 2.2 miles in length. The only visible portion of
the tunnel is a 125-foot-high surge tank constructed on the
hill above the plant to absorb hydraulic momentum of the water
in case of load rejection. The penstock must undergo a
federally required inspection every five years.
The powerhouse is located at Chelan Falls. It is 140 feet long,
100 feet wide and 124 feet high. Besides the two generating
units, the powerhouse contains a control room, shop facilities,
switching equipment, crane and communications equipment.
Water traveling down the power tunnel is directed against two
turbines rated at 42,662 horsepower each. The turbines, which
are connected to the generators by steel
shafts, rotate at 300 revolutions per minute. The original
turbines were replaced in 1985 and 1986, and those were
replaced in 2009 and 2010.
The generators are rated at 29,600 kilowatts each. Together,
they provide a normal operating output of 62
megawatts. The original generators were rewound in 1951 and
1952. New generators and other equipment were
installed in 2009 and 2010, increasing output by nearly 15
percent. After passing around and through the turbine
blades, water is discharged into the tailrace located on the
east side of the powerhouse where it flows into the Columbia
Electrical energy is distributed from the powerhouse to Chelan