[MUSIC]

Joan Cartan-Hansen, Host: Dams
are amazing to see, but if you

are going to visit, you do need
to be careful.

Be sure to obey all posted signs
and, if you're recreating, stay

well away from the dam itself.
While dams are engineering

marvels, every once in a while,
they do fail.

On average, ten dams fail in the
U.S. every year.

Most of these are very small,
causing little damage.

But when a major dam fails, it
can be catastrophic.

The most famous failure in Idaho
happened in 1976.

Engineers had just built the
Teton dam when it collapsed.

>>"People downstream better get
out."

The residents of Wilford had
only a few minutes of warning

before 80 million gallons of
water ripped through their

homes.
Flood waters wiped out many

communities
And destroyed thousands of acres

of farm land.
In the end, the flood cost

American taxpayers almost half a
billion dollars.

Engineers learned a lot from the
Teton dam failure.

They're using that new knowledge
to make today's dams safer.

For more information about dams,
check out the science trek

website.
You'll find it at science trek

dot org