The Teton Dam was a project of the U.S.
Bureau of Reclamation in
Idaho that
exemplifies the consequences of
unchecked bureaucracy. The dam was built in the early
1970s when the Bureau was running out of good places to put dams, but needed to keep building dams to justify its huge
budget and very existence. The dam was supposed to provide
irrigation water to area farmers, but the amount it would provide was very small, and the project could only be made to appear
marginally profitable with even the most
creative bookkeeping the bureau could muster. The local and state politicians were very much in favor of having the dam built, because huge projects mean jobs, and
tangible things like dams are easy ways to appear to be
getting things done.
The site chosen for the
earthfill dam was openly critcized by
geologists working for the
USGS for being on unstable rock in a
seismically active area, but their objections were ignored and glossed over by Bureau staffers. The rock on the right wall (looking
downstream) was quite
fractured, and as they dug the "bad rock" away they just found more. The fix was to "
grout" the cracked surface extensively before building the anchors for that side of the 300 foot high, 1,700 foot wide dam. The $85
million dollar dam was mostly completed in the Fall of 1975 , and in the Spring of 1976 a
burgeoning snowpack in the Teton Mountains was ready to fill the
reservoir behind the dam. In fact, the decision was made to let the dam fill at twice the normal rate, since the water was coming at a high rate and the main
outlet facilities - which allow dumping excess water at high rates - were not completed. There was actually little choice regarding the fill rate.
In mid-April the reservoir was filling rapidly. On June 3rd small springs, actually leaks, on the right canyon wall began appearing downstream from the dam, indicating that water from the reservior was going around the grouting and through the fractured rock. On June 5th, around 7:30 AM, a wet spot appeared on the face of the dam near the right wall; it quickly grew to a steady flow of water, then frantic gushing from a widening hole. The water flowing around the grout (under extreme pressure) had also found its way into the earthfill interior of the dam, where it turned the soil and rock to jelly as it sought a way out. At Noon the right 1/3 of the dam simply collapsed and disappeared in an incredible torrent.
The resulting
flood wiped out the town of
Wilford and
inundated several more before the flow joined the already swollen
Snake River just above the city of
Idaho Falls, which was spared because the residents had enough warning to
shore up and
sandbag their flood control
levees and the
porous area rock absorbed much of the excess flow. Only eleven people were killed, in large part because the dam had the grace to fail during the daytime when workers were watching. Aside from some petty local
political fallout, there were few consquences suffered by those not living in the path of the flood, and the Bureau returned to
business as usual after a short period of keeping it's head down.
The above summarized from:
"Cadillac Desert, The American West and its Disappearing Water" by Marc Reisner