Spirit Lake (Washington)
Overview
 
Spirit Lake is a lake
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

 north 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...

 in Washington State. The lake was a popular tourist destination for many years until the 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...

. With the eruption and resulting megatsunami
Megatsunami
Megatsunami is an informal term to describe a tsunami that has initial wave heights that are much larger than normal tsunamis...

, thousands of trees were torn from the surrounding hillside after lake water was displaced 800 feet up the hillside. 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...

 and pyroclastic flow
Pyroclastic flow
A pyroclastic flow is a fast-moving current of superheated gas and rock , which reaches speeds moving away from a volcano of up to 700 km/h . The flows normally hug the ground and travel downhill, or spread laterally under gravity...

 deposits from the eruption then blocked the North Fork Toutle River
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...

 valley at its outlet, raising the surface elevation of the lake by over 200 ft (61 m).
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