Marc Reisner pointed out in 1986 that the most prominent archeological evidence of Americans on this continent is silted-out dams. His forward for the book posits an alien race far in the future that will deduce we were waterfall worshipers, considering how many we will have created.

In 1963, humans stopped time, when the brand new Glen Canyon Dam on the Utah-Arizona border cut off the reddish sediment that naturally eroded the Grand Canyon. Today the river runs vodka clear from the base of the dam.

The destruction of the Glen Canyon Dam is the main through-line of Edward Abbey's The Monkey Wrench Gang. One of the characters, "Seldom Seen" Smith, is a bigamous jack mormon whose family farm was condemned and inundated at the dam's creation. Abbey was inspired to write Monkey Wrench Gang by a mysterious crime wave around Albuquerque NM in the '60s, when billboards along I-25 and I-40 spontaneously combusted, forcing the outdoor advertising companies to resort to steel construction. He hypothesized Doc Sarvis and Bonnie Abzug without knowing how close he was with Bonnie, anyway... in real life, the lady burning down billboards on the outskirts of town was my mother.

Each day on average for the past 60 years, the equivalent of 61 supersize Mississippi River barge-loads of sand and mud have been deposited there. The total accumulation would bury the length of Manhattan to a depth of 126 feet — close to the height of a 12-story building.

Reisner points out that the Army Corps of Engineers has long recognized that the life span of any given dam is 50-80 years, depending on weather conditions... but because of the bureaucratic framework of the ACE, "50-80 years" counts as "eternal" for bookkeeping purposes.

The bureau recently issued ideas to create new outlets for lake water at lower elevations in the dam so it can keep producing power and delivering water to users in the Southwest, Mexico and California. But there’s only one modification that would actually solve the sediment problem: boring two tunnels at the base of the dam, one at grade level with the riverbed. That would kill the reservoir but allow sediment to pass downstream. The bureau said this option had been discussed, but “not further considered.”

It is always discussed whenever a dam silts up, and is promptly rejected because any tunnel you dig will also silt up. The only way to fix a silted dam is to drain it, dismantle it, dig it out and rebuild it. This never happens because it's far more expensive than just abandoning the dam and building another one somewhere else. The trail of dead left by the Army Corps of Engineers is where most of the dam removal projects find fertile ground: it's a rare working dam that is removed, while silted over nightmares can generally be pulled out with nothing more than a fuckton of privately-sourced money.

Mr. DeHoff noted that the Bureau of Reclamation regularly monitored sediment in the early years of the reservoir. But it stopped in the wet years of the 1980s, saying it would take 7 centuries for Lake Powell to fill with soil.

Ahhh yes, the '80s.

A controversy erupted after a speech to the U.S. Chamber of Commerce in September 1983, when Watt mocked affirmative action with his description of a department coal leasing panel: "I have a black, a woman, two Jews and a cripple. And we have talent."

Mr. DeHoff of the Returning Rapids Project thinks the nutrient-rich sediment should be allowed to pass through a decommissioned Glen Canyon Dam, on to Lake Mead, where it could be shipped to farmers in places like California’s Imperial Valley.

Unfortunately the nutrients are soluble. The sediment is not. Silt is mostly sand, which is why the mud is so treacherous. Constant underwater flows generally separate the constituent mud into gravel, sand, decomposing organic matter and chemical compounds. The organic matter and compounds make it to the ocean, that's what makes deltas so lovely. Gravel generally gets left in the slow spots. Sand? Sand builds up in cataracts. A dam is a man-made cataract.

Jack Schmidt, director of the Center for Colorado River Studies at Utah State University, warns this is impossible, given the volume of mud. His solution? Move the sediment further downriver. That will be very expensive — in the tens of billions of dollars. Moving sediment through the dams involves dredging or piping sand and mud long distances. And the dam itself would have to be redesigned to allow silt to pass through it.

This design does not exist, has never existed and will never exist. It is possible to design a catchment basin to minimize the silt accumulated but you can no more make a dam that won't silt than you can make a filter that won't clog.

For now, the Bureau of Reclamation isn’t commenting on draining Lake Powell.

Do you want to be the guy who says "we expect you to be the Salton Sea pretty soon?"

It does have the expertise to decommission Glen Canyon Dam today, and begin studying how to move sediment downriver through the dams. It will take years to implement any plan.

Churchill figured out how to decommission dams with a quickness.

Lake Powell, I believe, is the one that should be drained. And then Glen Canyon should be declared a national park. It was the most beautiful stretch of the Colorado River, and if we allow nature to do its work, the entire canyon would return to what it looked like in Eliot Porter’s book.

Ultimately? We probably shouldn't have so many people inhabiting the Great American Desert.