Culmback Dam

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Culmback Dam
The reservoir (Spada Lake) from the air with the dam at the left end of the lake
The reservoir (Spada Lake) from the air with the dam at the left end of the lake
Location: Snohomish County , Washington (USA)
Tributaries: Sultan River
Drain: Sultan River
Culmback Dam (Washington)
Culmback Dam
Coordinates 47 ° 58 ′ 31 ″  N , 121 ° 41 ′ 11 ″  W Coordinates: 47 ° 58 ′ 31 ″  N , 121 ° 41 ′ 11 ″  W
Data on the structure
Construction time: 1960-1965
Height of the barrier structure : 80 m
Crown length: 200 m
Power plant output: 112 MW
Operator: Snohomish County PUD
City of Everett
Data on the reservoir
Altitude (at congestion destination ) 440 m
Water surface 760 hadep1
Total storage space : 204 479 000  m³
Catchment area 220 km²

The Culmback Dam (also George Culmback Dam or Snoqualmie National Forest Dam ) is a large dam , which is used to generate electricity and water, on the Sultan River , a tributary of the Skykomish River in Snohomish County in Washington state . It was built in 1965 and is 200 m long and 80 m high at the crown. The dammed lake, Spada Lake, supplies 70 to 75 percent of Snohomish County with water; the hydropower plant, located downstream from the dam, has an output of 112 megawatts. Some reviews blame the dam for seriously interfering with the migration of salmon and other migratory fish in the Sultan River by cutting off the downstream transport of gravel and other sediments required to create the riverbed. In such cases, the operators of the dam counter that the Culmback Dam significantly reduces the risk of flooding and promotes fish populations and the surrounding communities. The dam was named in honor of George Culmback, a former Mayor of Everett. The dam is jointly owned and operated by the Snohomish County Public Utility District (PUD) and the City of Everett . The water from Spada Lake is diverted into a pipeline and fed to a power station a little below the dam on the Sultan River. From the power station, some of the water is returned to the river and the other is directed to Lake Chaplain, where it is fed into Everett's water supply.

history

Before 1917, the city of Everett got its water from Woods Creek, another tributary of the Skykomish River . Due to the increasing demand for water in the large paper mills and other factories, the city changed the source of the water by using the Sultan River Basin via the Chaplain Creek tributary. The Chaplain Reservoir was created in 1929 with the completion of an earth dam, which was increased in 1942. The supply was still inadequate, so engineers set about damming the main arm of the Sultan River, where an excellent site for a dam had been identified.

The Culmback Dam was built in two phases. Phase 1, from 1960 to 1965, involved building the dam up to a height of 61 meters with a reservoir of 49 million cubic meters. The work during this phase served to replace the smaller, 6.7 m high tipping structure 10.5 km downstream on the Sultan River. Phase 2, completed in 1984, included raising the dam by 19 m to its current height, thereby quadrupling the storage space. The second phase also included the construction of a pipeline from Spada Lake to a new hydropower plant and from there to the Chaplain Reservoir.

geography

The Sultan River in Sultan (Washington) .

The Culmback Dam and Spada Lake get their water from a catchment area of 220 square kilometers on the western slope of the Cascade Range . Although the wide valley in which the reservoir lies today was created before the last glaciation, the canyon in which the dam was built was created about a million years ago when the Sultan River crossed the approximately one mile (1.6 km) the mighty Laurentide Ice Sheet was interrupted, which shifted the course of the river from its original catchment area on the Pilchuck River . The river dug a narrow canyon and eventually poured into the Skykomish River , creating an ideal site for a dam. The Sultan River, formed by the confluence of the North Fork Sultan River and Elk Creek, flows into the lake from the east. Additional important tributaries are the South Fork, which forms an arm closely tied to Stickney Ridge, and Williamson Creek, which opens at the foot of Big Four Mountain .

Water supply and energy generation

Spada Lake is part of the water supply for the city of Everett. This water supply is based on two lakes, Spada Lake and the much smaller Lake Chaplain (about 21 million m³) on Chaplain Creek, a tributary of the Sultan River. Most of the Sultan River's runoff is discharged at the dam into a 12.6 km long pressure pipe that leads to the 112 MW Jackson power plant with a height difference of 355 meters. In the power plant, the water drives four turbine / generator units, which consist of two 47.5 MW Pelton and two 8.4 MW Francis turbines . The water from the Pelton turbines is fed directly into the Sultan River, while the rest is fed into Lake Chaplain.

The water flows from Lake Chaplain to Everett in four pipes 1.2 meters in diameter. During a flood, the water is also returned directly to the Sultan River through Chaplain Creek and the Sultan River Fresh-water Return Line. The Culmback Dam is able to divert water through an overflow , the capacity of which is 1,800 m³ / s, which is sufficient to intercept a century flood of the Sultan River, which was calculated at 1,300 cubic meters per second.

Individual evidence

  1. ^ A b Everett Water System-Culmback Dam . Archived from the original on September 5, 2008. Retrieved February 20, 2009.
  2. ^ A b Jackson Hydro Project History . Archived from the original on November 21, 2007. Retrieved February 21, 2009.
  3. ↑ Culmback Dam in the Geographic Names Information System of the United States Geological Survey
  4. ^ A b c Everett, Washington Water Supply-Culmback Dam . Archived from the original on October 31, 2007. Retrieved February 20, 2009.
  5. ^ A b Foundation for Water and Energy-Testing the waters . Retrieved February 20, 2009.
  6. ↑ Snohomish County PUD Jackson Hydro Project . Retrieved on February 12, 2009  ( page no longer available , search in web archives )@1@ 2Template: Dead Link / www.snopud.com
  7. ^ A b City of Everett Water Supply . Archived from the original on October 6, 2011. Retrieved February 20, 2009.
  8. ^ History Lesson in Everett . Archived from the original on June 13, 2010. Retrieved February 21, 2009.
  9. ↑ EverettWashington.org- Sultan River . Archived from the original on October 31, 2007. Retrieved February 21, 2009.
  10. ↑ Sultan River Flood Flows ( PDF ) Archived from the original on October 6, 2011. Retrieved on February 21, 2009.