Lake Shannon
| Lake Shannon | |
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Lake Shannon looking downstream during the floods of 2003, with the Lower Baker Dam in the distance
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| Location | North of Concrete, Skagit County, Washington, US |
| Coordinates | 48°32′51″N 121°44′28″W / 48.54750°N 121.74111°WCoordinates: 48°32′51″N 121°44′28″W / 48.54750°N 121.74111°W |
| Type | Reservoir |
| Primary inflows | Baker River, Thunder Creek, Sulphur Creek, other small tributaries |
| Primary outflows | Baker River |
| Catchment area | 270 square miles (700 km2) |
| Basin countries | United States |
| Built | April 1, 1924 |
| First flooded | September 1, 1925 |
| Max. length | 7.5 miles (12.1 km) |
| Max. width | 1 mile (1.6 km) |
| Surface area | 2,190 acres (8.9 km2) |
| Average depth | 70 feet (21 m) |
| Max. depth | 280 feet (85 m) |
| Water volume | 161,470 acre feet (199,170,000 m3) |
| Surface elevation | 436 feet (133 m) at full pool |
| Frozen | In winter |
| Islands | 1, unnamed, near north end |
| Settlements | Concrete |
Lake Shannon is a long, narrow reservoir on the Baker River in Skagit County, Washington in the United States. Formed in the 1920s by the construction of an arch dam just above the town of Concrete, the lake is approximately 7.5 miles (12 km) long and averages 0.6 miles (1 km) wide when full. Located just outside the western boundary of North Cascades National Park in the Mount Baker National Forest, Lake Shannon serves as the lower reservoir for Puget Sound Energy's Baker River Hydroelectric Project.
Before the creation of Lake Shannon, the area was used primarily for fur trapping, logging, and concrete making. The construction of Lower Baker Dam blocked salmon migration in the Baker River. An artificial fish passage system was begun in the 1950s and completed in 1959 after the construction of Upper Baker Dam, located upstream of Lake Shannon. The lake has abundant landlocked kokanee salmon, the by-product of salmon spawning in lake tributaries. Fishing, boating and water skiing are popular recreational activities on the lake.
The Baker River flows southeast and south for about 30 miles (50 km) to meet the Skagit River at Concrete. Less than 1 mile (1.6 km) above its mouth, a 285-foot-high (87 m) arch dam, the Lower Baker Dam, straddles an extremely tight and narrow gorge to form Lake Shannon, a 2,190-acre (8.9 km2) lake.
The lake occupies a cleft in the Baker River Valley between a prominent river terrace to the west and a less obvious one on the east. While the west slope directly above the lake is dissected with many canyons, the east slope is smaller and smoother. The lake is surrounded by prominent forested mountains, but the surrounding terrain is not as steep and rugged as the upper watershed.
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