Army Corps of Engineers Facts

Mount St. Helens threw a forest into Spirit Lake in 1980, and thousands of those logs still float there today. The landslide raised the lake about 200 feet and buried its outlet. To stop it bursting out and flooding the towns below, the Army Corps built a tunnel over a mile and a half long through a ridge, finished in 1985. It is still the lake's only drain, and it keeps buckling.

They turned Niagara Falls off. In 1969, the U.S. Army Corps of Engineers dumped 28,000 tons of rock into the Niagara River, stopping the American Falls completely for five months. Tourists walked the dry riverbed and found millions of coins - and engineers discovered the fallen boulders below were holding the falls up.