The Toutle River is a river in southwestern Washington State, in the Pacific Northwest

Pacific Northwest

The Pacific Northwest is a region in northwestern North America, bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Definitions of the region vary and there is no commonly agreed upon boundary, even among Pacific Northwesterners. A common concept of the...

 region of the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. It rises in two forks on the flanks of Mount St. Helens

Mount St. Helens

Mount St. Helens is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. It is south of Seattle, Washington and northeast of Portland, Oregon. Mount St. Helens takes its English name from the British diplomat Lord St Helens, a...

 and joins the Cowlitz River

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....

 near Castle Rock

Castle Rock, Washington

Castle Rock is a city in Cowlitz County, Washington, United States. Nestled between the Willapa Hills and western base of Mount St. Helens, Castle Rock is at the heart of Washington timber country in the Pacific temperate rain forest...

.

Eruption of Mount St. Helens

The May 18, 1980 eruption of Mount St. Helens

1980 eruption of Mount St. Helens

The 1980 eruption of Mount St. Helens, a stratovolcano located in Washington state, in the United States, was a major volcanic eruption. The eruption was the only significant one to occur in the contiguous 48 U.S. states since the 1915 eruption of Lassen Peak in California...

 and subsequent lahar

Lahar

A lahar is a type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris, and water. The material flows down from a volcano, typically along a river valley. The term is a shortened version of "berlahar" which originated in the Javanese language of...

s poured vast amounts of sediment

Sediment

Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....

 into the Toutle, which was formerly navigable. The US Army Corps of Engineers dredged 85 million m³ (110 million yd³) of sediment from the river and built the US$65 million Sediment Retention Structure

Toutle River Sediment Retention Structure

The Sediment Retention Structure is a , earthen dam on the North Fork of the Toutle River in Washington. Its construction was completed by the US Army Corps of Engineers in 1989. Its purpose is to retain sediment created since the 1980 eruption of Mount St...

 on the North Fork of the Toutle

North Fork Toutle River

The North Fork Toutle River is a tributary of the Toutle River in the southwestern Washington in the United States. The river has its headwaters near Spirit Lake, on the north side of Mount St. Helens, and flows about to the Toutle River, upstream of its confluence with the Columbia River...

 to keep it clear in the future. Part of the same engineering works is a tunnel to drain Spirit Lake

Spirit Lake (Washington)

Spirit Lake is a lake north of Mount St. Helens in Washington State. The lake was a popular tourist destination for many years until the 1980 eruption of Mount St. Helens. With the eruption and resulting megatsunami, thousands of trees were torn from the surrounding hillside after lake water was...

whose natural outlet was blocked by the eruption.

External links

• Taming the Toutle River Seattle Times, October 25, 2004
• Sediment Retention Structure – U.S. Army Corps of Engineers