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

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