The North Fork Toutle River is a tributary of the

Toutle River The Toutle River is a tributary of the Cowlitz River in the U.S. state of Washington. It rises in two forks merging near Toutle below Mount St. Helens and joins the Cowlitz near Castle Rock, upstream of the larger river's confluence with the Co ...

in southwestern

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered on ...

in the United States. The river has its headwaters near Spirit Lake, on the north side of

Mount St. Helens Mount St. Helens (known as Lawetlat'la to the indigenous Cowlitz people, and Loowit or Louwala-Clough to the Klickitat) is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United St ...

, and flows to the Toutle River, about upstream of its confluence with the

Cowlitz River The Cowlitz River is a river in the state of Washington in the United States, a tributary of the Columbia River. Its tributaries drain a large region including the slopes of Mount Rainier, Mount Adams, and Mount St. Helens. The Cowlitz has a ...

River mile A river mile is a measure of distance in miles along a river from its mouth. River mile numbers begin at zero and increase further upstream. The corresponding metric unit using kilometers is the river kilometer. They are analogous to vehicle road ...

s are marked and numbered on the relevant map quadrangles. The largest tributary is the

Green River Green River may refer to: Rivers Canada *Green River (British Columbia), a tributary of the Lillooet River *Green River, a tributary of the Saint John River, also known by its French name of Rivière Verte *Green River (Ontario), a tributary of ...

, which joins near the unincorporated town of Toutle. The North Fork's watershed was severely affected by the

1980 eruption of Mount St. Helens On March 27, 1980, a series of volcanic explosions and pyroclastic flows began at Mount St. Helens in Skamania County, Washington, United States. A series of phreatic blasts occurred from the summit and escalated until a major explosive eru ...

, which coated the valley with ash and filled it with successive mudflows. The result of the eruption was that many hillsides were stripped of forest, and as a result erosion has increased dramatically and the North Fork is now extremely laden with sediment. Previously, Spirit Lake was the source of the river, but eruptions blocked the outlet and Spirit Lake no longer drains directly into the North Fork; instead, a tunnel was excavated in 1985 to connect the lake with South Coldwater Creek, a tributary of the North Fork. Once a mature river, the North Fork has transformed into a

braided stream A braided river, or braided channel, consists of a network of river channels separated by small, often temporary, islands called braid bars or, in English usage, ''aits'' or ''eyots''. Braided streams tend to occur in rivers with high sediment lo ...

of relatively young origin, and its valley floor is less than three decades old. The Toutle River Sediment Retention Structure was built by the

U.S. Army Corps of Engineers , colors = , anniversaries = 16 June (Organization Day) , battles = , battles_label = Wars , website = , commander1 = ...

on the river in 1989 to prevent this sediment from traveling downstream and clogging the shipping channel of the Columbia River. The upper part of the North Fork Toutle River watershed was redirected to the crater of Mount St. Helens itself until 1982. The river's headstreams begin on a volcanic ash deposit roughly long and deep, which is the source of much of the excess sediment.

References

External links

Background about the river from USGS website
{{authority control Toutle River North Fork Braided rivers in the United States Rivers of Cowlitz County, Washington Toutle River North Fork Toutle River North Fork Toutle River North Fork

See also

References

External links