Tuesday, June 2, 2015

Crater and Lake (But Not Crater Lake)

Washington - Mount St. Helens

For: US to US Travelling Envelope Round Robin - Flight 4
Notes: Mount St. Helens is most famous for its eruption on May 18, 1980 that destroyed 250 homes, 47 bridges, 15 miles (24 km) of railroad and 185 miles (298 km) of highway.  It also filled Spirit Lake, seen here in the foreground, was filled with debris from the eruption, including trees, other plants, volcanic ash and volcanic debris.  All of this blocked the lake's pre-eruption outlet to the North Fork Toutle River valley, which raised the surface elevation of the lake by about 200 feet (60 m).  In order to maintain the current water level, the U.S. Army Corps of Engineers built a tunnel to allow drainage to South Coldwater Creek.  If they had not built the tunnel, the log dam blocking the lake's natural outlet would have broken, creating a massive flood downstream.

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