The Year the Dam (Almost) Broke
The cycle of extreme floods and droughts during the past dozen years illustrates how fragile is our hold on the water that sustains the West.
It seems like ancient history now, but it was only a few years ago that drought busters roamed L.A. streets and issued citations for wasting water; California, Nevada and Arizona were denied Colorado River water for the first time; Lake Powell recorded its lowest levels from 1987 to 1992.
Yet it was during the summer of 1983 that the Bureau of Reclamation almost lost control of the Colorado River to a rampaging flood.
Normal runoff from the snowpack along the Continental Divide was forecast that year, so Lake Powell, which straddles the Utah-Arizona border, was drawn down only slightly. Hot weather and rain altered the picture, and the actual runoff was 210% of normal.
Upstream from Lake Powell, rivers flooded and dams spilled. The raging earth-tinted waters from the swollen tributaries emptied into the placid lake. The water level began its inexorable rise in the 186-mile-long reservoir and neared the top of Glen Canyon Dam.
Afterward, the bureau would state that the dam had never been endangered, but documents show that bureau engineers feared “for the safety of the dam and its foundation.”
Two thousand tons of water per second soared from the dam’s two spillways and river outlets. Rumbling noises were heard in early June. Chunks of rocks and pieces of concrete issued from the spillway tunnels, as if the dam was mortally wounded.
Despite the apparent damage, the spillway gates needed to be kept partially open because the reservoir was rising almost six inches a day. Yet water also needed to be contained. Hoover Dam, 402 miles downstream, had safety problems of its own, and releases from Hoover could cause extensive flooding and damage all the way to the Gulf of California, as it eventually did that year.
Top bureau officials met in late June and established a maximum water level of 3,708 feet above sea level for Lake Powell. At 3,708.40 feet, the engineers thought they would lose control of the spillway gates. Four-foot-high plywood sheets were added to the gates. The water rose and lapped over them. The plywood was replaced by eight-foot steel plates. The water still rose.
When engineers inspected the spillway tunnels, they saw that house-sized holes had been punched through the concrete lining and into the sandstone. They thought the sandstone might erode, causing “an uncontrolled release,” according to a memo.
What would then happen was anyone’s guess. A wall of water could have roared through the Grand Canyon and overwhelmed everything in its path, starting with Hoover Dam. The subsequent huge loss of life, property, power and water would have been disastrous.
The level of the reservoir peaked at 3,708.34 feet on July 15, six-hundredths of a foot below the point where officials feared they’d lose control. It held steady for a few days and then gradually declined.
A collective sigh of relief echoed through bureaucratic corridors in Washington, D.C., and the western states; but only a muted whisper of what actually occurred ever escaped from those confines.
The ghost of the untamed river had almost achieved what Edward Abbey, author of “Desert Solitaire” and “The Monkey Wrench Gang,” and his radical environmental followers had fantasized--the destruction of Glen Canyon Dam.
Repairs were started immediately and completed in 1984, another high-water year. But the bureau was prepared, and Lake Powell was drawn down. The next two years were wet; and then, in 1987, the drought began and reservoir levels shrank.