Lake Shannon

from Wikipedia, the free encyclopedia
Lake Shannon
Looking across Lake Shannon downstream during the 2003 flood, with Lower Baker Dam in the background
Looking across Lake Shannon downstream during the 2003 flood, with Lower Baker Dam in the background
Location: Skagit County , Washington (USA)
Tributaries: Baker River , Thunder Creek, Sulfur Creek, other small tributaries
Drain: Baker River
Major cities nearby: Concrete
Lake Shannon (Washington)
Lake Shannon
Coordinates 48 ° 32 '51 "  N , 121 ° 44' 28"  W Coordinates: 48 ° 32 '51 "  N , 121 ° 44' 28"  W.
Data on the structure
Construction time: April 1, 1924 - September 1, 1925
Data on the reservoir
Altitude (at congestion destination ) 133  m
Water surface 8.9 km²
Reservoir length 12.1 km
Reservoir width 1.6 km
Maximum depth 85 m (mean depth 21 m)
Total storage space : 199,170,000 m³
Catchment area 700 km²
Particularities:

frozen over in winter, a nameless island at the north end

The Lake Shannon is a long, narrow reservoir on the Baker River in Skagit County in the State of Washington . The lake was created in the 1920s through the construction of an arched dam above Concrete . It is approximately 12.1 km long and an average of 1.6 km wide when fully dammed. With a location just outside the western boundary of the North Cascades National Park in the Mount Baker National Forest Lake Shannon serves as deeper situated reservoir for the Baker River Hydroelectric Project of Puget Sound Energy .

Before the Lake Shannon dam, the area was primarily used by trappers and loggers, as well as for concrete production. The construction of the Lower Baker Dam blocked the migration of salmon in the Baker River. Construction of an artificial fish ladder began in the 1950s and was completed in 1959 after the construction of the Upper Baker Dam , which is upriver from Lake Shannon. The lake is home to a large population of the sockeye salmon , the non-migratory form of which is called "Kokanee"; the population is considered a by-product of fish farming in the tributaries. Fishing , boating and water skiing are popular recreational activities on the lake.

geography

The Baker River flows for 48 km southeast and south to its confluence with the Skagit River at Concrete. Less than a mile (1.6 km) above the estuary blocks an 87 m high arched dam, the Lower Baker Dam, an extremely narrow gorge to form Lake Shannon, an 8.9 km² reservoir.

The lake fills a rift in the Baker River Valley between an exposed river terrace in the west and a less exposed one in the east. While the western slope is furrowed by many canyons directly above the lake, the eastern slope is shorter and smoother. The lake is surrounded by striking forested mountains, but the surrounding area is not as steep and rugged as the upper catchment area.

The reservoir is widest in the lower half, especially in an area about five kilometers above the dam. Near the center, the shores of the lake come very close together when it squeezes between the western shore and a protruding cape. The upper half of the lake is very narrow and the extreme upper end protrudes into Mount Baker National Forest . Exactly above the northern end of the lake, the Upper Baker Dam seals off the Baker River again and forms the extensive Baker Lake .

The area is dominated by Mount Baker , a few miles northwest of Lake Shannon towering 3,286 m high. Mount Shuksan , a slightly smaller peak, rises more north-northeast to 2,782 m. Apart from the Baker River, the main tributaries are Thunder Creek (which flows into the lake near the cape, which almost divides it into two halves) and Sulfur Creek, which flows directly into the lake during high tide.

The Baker River Road runs in a northerly direction together with the east side of Lake Shannon into the North Cascades National Park, while the North Cascades Highway (Washington State Route 20) crosses the Baker River just below Lake Shannon. Although most of the Lake Shannon's tributary comes from the Upper Baker Dam drain, it has an additional drainage basin of 210 square kilometers.

Buildings

An arch dam blocks a narrow, wooded canyon above a white water river
The Lower Baker Dam from the lower reaches of the river

The Lower Baker Dam ( 48 ° 32 ′ 51 ″  N , 121 ° 44 ′ 28 ″  W ) was built in 1925 as the first of two dams for power generation in the Baker River Hydroelectric Project ; it belongs to Puget Sound Energy . It is a thick arch dam 87 meters high and 270 meters long. The drains are located on the crown and consist of 24 openings. A pressure pipe leads the water from the lake to the power station on the left bank of the river; the output of the power plant is 79 MW; the water is fed back into the river immediately at the foot of the dam. This leads to a stretch in the river that is dry most of the time. When the water is completely blocked, the lake level reaches 134 meters above sea level, when the water is completely drained it is 104 meters; the minimum water level for operating the power plant is 110 meters. The reservoir contains almost 200 million m³ of water when it is completely blocked.

Below the Lower Baker Dam there is a "fish ladder" in the town of Concrete. The concrete weir represents the first stage of a channel that allows anadromous fish to migrate upstream to Baker Lake, from where they can migrate further up the Baker River to their spawning areas.

history

Before the construction of the Baker River Project , Lake Shannon did not even exist; Baker Lake was a smaller lake created by a glacial moraine . Anadromous fish could migrate up the Baker River in numbers up to 20,000 each spring. In the 19th century, the area around the Baker River was mainly used for forestry . Large deposits of building lime in the mouth of the Baker River led to the construction of a cement factory in what is now Concrete.

Map of the catchment area of ​​the Skagit River with Lake Shannon on the Baker River (approximately in the middle)

On April 1, 1924, construction of the Lower Baker Dam officially began by the Stone & Webster Company at a location known as Eden Canyon. At first 150 people worked on the project, but their number grew to 900 by the following year. In early 1925, the Lower Baker Dam was completed by around 1,300 workers at a height of 70 meters and in November of the same year the reservoir was dammed up to its capacity for the first time. (The dam was later raised 27 m to its present height.) The jam flooded the first railway bridge over the river, the Baker River Bridge, a 58 m high wooden trestle bridge. The power plant supplied the first electricity on November 19, 1925.

The construction of the dam and the damming of the lake had a serious impact on salmon in the Baker River - the dam left only a mile of the river accessible to fish. Before it was built, around 20,000 fish returned to their spawning grounds annually. Later, the returnees rarely exceeded 3,000 fish and declined even more in the 1980s to a minimum of 99 in 1985. Below Lake Shannon, a structure was built across the Baker River, which was originally used to catch the returning anadromous fish; along with a few other facilities, the fish were transported to Lake Shannon until 1959. The system was then expanded and the fish were brought directly into Baker Lake.

On July 9, 1959, the Upper Baker Dam was completed and the inflow to Lake Shannon was regulated for the first time. A major landslide in 1965 crushed the machine building with turbines 1 and 2 at Lower Baker Dam. Units 3 and 4 were built at the same location and the original 300 m long pressure tunnel was extended by 130 m to 430 m in order to be able to reach the new machine house. The new building was provided with a sloping roof in order to minimize the potential for destruction. In 1991, in another project, the Koma Kulshan Project , about 3.4 m³ / s were diverted from two western tributaries of Lake Shannon to Baker Lake in order to drive a run-of-river power station .

nature

One of the most common fish species in Lake Shannon is the sockeye salmon or its non-migratory form "Kokanee", but this population differs from other Kokanees. The real Kokanees are born in fresh water; it is possible that Lake Shannon's Kokanees are a cross of sockeye salmon and silver salmon that grow in the lake's tributaries - including Sulfur Creek and Thunder Creek - either on natural gravel banks or man-made ones. Some of the juvenile fish escaped from the channels that direct the migrating young salmon into the Lower Baker and Skagit Rivers, creating a Kokanee population. There is also a population of bull trout in the lake.

The Lake Shannon area is dominated by Douglas firs and other conifers as well as deciduous trees.

tourism

Lake Shannon is about a mile north of Concrete and 35 miles east of Mount Vernon . The lake itself is most commonly accessed via the Baker River Road, which currently runs up the river valley to the border of North Cascades National Park . Parts of Lake Shannon lie within the Mount Baker National Forest , which also contains the entire Baker Lake. Swimming, boating and water skiing can be practiced in and on the lake, and sockeye salmon are a frequent target for anglers. However, the only way to get boats into the lake is through private land. In most years the lake is open to anglers from the last Saturday in April to October 31st. There are plans to expand the existing hiking trail system around the two reservoirs by around 12.6 km as well as other general improvements in the area of ​​the hydropower project.

Individual evidence

  1. ↑ a b data on the lake
  2. ↑ [ https://geonames.usgs.gov/apex/f?p=gnispq:3:::NO::P3_FID:1525616 Lake Shannon] in the Geographic Names Information System of the United States Geological Survey
  3. ↑ a b c d e Baker River Project - Initial Consultation Document, Existing Conditions, Chapter 3-3 . Puget Sound Energy. March 2002. Retrieved on September 1, 2009. Template: dead link /! ... nourl ( Page no longer available )
  4. ↑ a b Baker River Project - Initial Consultation Document, Existing Conditions, Chapter 3-11 (Aesthetic Conditions) . Puget Sound Energy. March 2002. Retrieved on September 1, 2009. Template: dead link /! ... nourl ( Page no longer available )
  5. ↑ a b ACME Mapper. USGS Topo Maps for United States [map]. Cartography from United States Geological Survey . Retrieved October 29, 2009.
  6. ^ Baker River Hydroelectric Project . Puget Sound Energy. Archived from the original on January 4, 2011. Retrieved August 31, 2009.
  7. ^ Lower Baker Dam / Lake Shannon . Skagit River History website. June 14, 2006. Retrieved September 1, 2009.
  8. ↑ PSE's New Baker River $ 50 Million Fish Passage System Generating Success in First Few Weeks of Operation . redOrbit. May 19, 2008. Retrieved September 1, 2009.
  9. ^ Baker River Project - Initial Consultation Document, Existing Conditions, Chapter 3-1 . Puget Sound Energy. March 2002. Retrieved on September 1, 2009. Template: dead link /! ... nourl ( Page no longer available )
  10. ^ Great New Baker Plant Completed in Record Time . In: The Concrete Herald , November 26, 1925. Retrieved September 2, 2009. 
  11. ^ Larry Kunzler: Historical Record of Dam Building and their Impacts on Floods of the Skagit River - 1924 through 1968 . Skagit River History website. May 22, 2005. Archived from the original on July 16, 2011. Retrieved September 1, 2009.
  12. ^ Photos of logging and cement trains and trestles in old Concrete, Washington . In: Skagit River Journal . The Stump Ranch. Retrieved September 1, 2009.
  13. ^ First Power from Baker River Plant Turned Out Today . In: The Concrete Herald , November 19, 1925. Retrieved September 1, 2009. 
  14. ↑ Eric Pryne: Baker River Salmon Pass While Other Fish Runs Fail - Imperiled Sockeye Return to Spawn in Record Numbers . In: The Seattle Times . September 6, 1994. Retrieved September 1, 2009.
  15. ^ Puget Sound Energy's Fish-Enhancement Efforts Contribute to Record Half-Million Baker River Juvenile Salmon Heading to Sea . In: EarthTimes , June 16, 2009. Retrieved September 4, 2009. 
  16. ^ Paul S. Fisk, Roberto Guardia, Wayne Porter: Lower Baker Tunnel Investigation and Repairs . NDT Corporation. Archived from the original on May 10, 2008. Retrieved September 1, 2009.
  17. ↑ Baker River Sockeye . Washington Department of Fish and Wildlife. Archived from the original on August 5, 2008. Retrieved September 1, 2009.
  18. ↑ a b Washington Fishing Prospects . Washington Department of Fish and Wildlife. Archived from the original on September 9, 2007. Retrieved September 1, 2009.
  19. ↑ Jeffrey Koenings: Director's report to the Fish and Wildlife Commission . In: Washington Department of Fish and Wildlife . wdfw.wa.gov. March 4, 2005. Archived from the original on January 13, 2010. Retrieved on September 4, 2009.
  20. ^ Baker River, Washington: 2004 Settlement Agreement Signed for 2 Dams (pdf) US National Park Service . Retrieved September 2, 2009.
  21. ^ Puget Sound Energy says the new license would require spending $ 360 million over 30 years . In: Foundation for Water and Energy Education . Retrieved September 4, 2009. 
  22. ↑ PSE Awarded New 50-Year License for Baker Hydropower Facility: Years of Collaborative Negotiation Led to Comprehensive Relicensing Agreement for Low-Cost Power, Improved Flood Control, Fish Protection and Public Recreation . In: BusinessWire . October 20, 2008. Retrieved September 1, 2009.

Web links