December 5, 2013
Glen Canyon Dam and the 1983 Flood
by Dana Thomas
This is my second paper for the Fortnightly Club. The first dealt with the disappearance of Everett Ruess during the 1930s in the slot canyons near Escalante,
Utah. This second paper finds us back in the red rock country of Arizona and Utah, but this time not exploring the mythical disappearance of quixotic young man, but rather examining a series of events and miscalculations that put Glen Canyon Dam on the path to failure. A failure that could have resulted in a wall of water 520 feet high rushing down the Colorado River through the Grand Canyon, spreading across Lake Mead, cresting Hoover Dam and reeking havoc all the way to the Gulf of Mexico.
Colorado River Compact
The story of Glen Canyon Dam begins in 1922, long before the dam was conceived, when the Colorado River Compact was crafted to distribute Colorado River water among the seven states of the Colorado Basin. The Compact split the Colorado’s watershed into upper and lower basins. The upper basin consisted of Wyoming, Colorado, Utah and New Mexico. Lower basin states included California, Arizona and Nevada. The agreement used historical water flows from 1899 to 1921 to allocate the water between the basins. This 22 year period suggested that the average annual flow of the Colorado River was 17.0 million acre feet. The agreement specified that the upper basin states would be entitled to 7.5 million acre feet each year, but were obligated to deliver 7.5 million acre feet to the lower basin states. In 1944 a treaty with Mexico provided that 1.5 million acre feet would be allowed to cross the border. Mexico’s allotment would come equally from the upper and lower basins.
The Colorado River Compact based its allocation of water on one of the wettest periods in the American west, leading to a significant over estimate of the amount of water available for allocation. The original estimate of 17.0 million acre feet was higher than the actual average of 14.0 million, forcing the allocation of the Colorado River into a deficit position even before development could begin. Allocating the Colorado, although a long and painstaking process filled with political intrigue was perhaps the easiest part of the job. In 1922, the river was wild and unpredictable and controlling it, much less dividing it up was a theoretical exercise.
Hoover Dam and Lake Mead
In 1934 the Federal Bureau of Reclamation, began to harness the Colorado River by building Hoover Dam at Black Canyon between Arizona and Nevada. Hoover Dam was a huge step forward in engineering and was the most ambitious of the many dams being built in the western United States for water storage, flood control and the generation of electricity. Built to serve the lower basin states it created Lake Mead that stretched northeast into the western end of the Grand Canyon. Lake Mead is the largest man made lake in the United States, holds 28.0 million acre feet of water, has 550 miles of shoreline and is 112 miles in length. Hoover Dam and the new technology introduced during its construction laid the groundwork for the many dams that followed and made Glen Canyon Dam feasible. The dam is a concrete arch-gravity design with both the base and sides sunk into igneous bedrock to ensure maximum strength. The arch design transfers the force of the weight of Lake Mead’s water into the rock on the sides and bottom of Black Canyon. The cost of the dam including change orders and additions was $54 million.
The Bureau of Reclamation calculated that if the concrete was poured in one massive piece, the dam would take up to 125 years to cool. In addition, the stresses caused by the cooling and contraction would cause cracking and put the dam at risk of failure. To solve this problem, the concrete was poured into blocks that were arranged in columns, thus reducing the mass of each pour. To further aid with cooling, pipes were imbedded in the concrete and ice-water from a refrigeration plant was circulated through each successive pour. A total of 3.3 million cubic yards of concrete were used in the dam, through which 582 miles of cooling pipes were run.
Hoover dam did have an engineering flaw that is important to the Glen Canyon Dam story. This flaw was the use of the lower half of the river bypass tunnels as the bottom portion of the spillways. The bypass tunnels were drilled during construction and were used to route the Colorado around the construction site. These tunnels were built with a low gradient. Two spillway tunnels, one on the Arizona side and one on the Nevada side, were designed to prevent the lake from overtopping the dam during times of high water. The spillways were started just below the top of the dam and were routed at a steep gradient until they joined with the bypass tunnels. Incorporating the bypass tunnels into the spillways created an elbow where the tunnels met. This approach saved drilling costs and was believed to be adequate until a belated test of the spillway on the Arizona bank was performed in 1941. The test specified a controlled flow of 13,000 cubic feet per second (cfs), but after the spillway gate failed, the flow increased to 40,000 cfs. When the gate was repaired and flow brought under control, engineers found extensive damage to the spillway. The worst of the damage was at the point where the spillway met the bypass tunnel. The water had carved out a huge hole 115 feet long and 45 feet deep. The damage was repaired and the spillways would not be opened again until the flood of 1983.
Colorado River Storage Project
Hoover Dam and Lake Mead along with downstream dams, Parker and Davis were promoted by California legislators and the project was designed to serve the growing population of Southern California. The upper basin states received no benefit from Lake Mead and Hoover Dam. In order, to use the 7.5 million acre feet of water allocated to them, to consistently deliver the 7.5 million acre feet due the lower basin states and the 1.5 million acre feet promised to Mexico, the upper basin needed to develop their own storage capacity. In 1956, the United States Congress passed legislation authorizing the Secretary of the Interior to build nine dams in the upper Colorado River Basin including Glen Canyon Dam.
The Colorado River Storage Act was from its outset controversial. In addition, to the nine dams eventually built under the act, the original vision called for a dam to be built in Echo Park in Dinosaur National Monument. This dam would have created a reservoir that backed up both the Green and the Yampa Rivers. An array of environmental organizations aligned against the Echo Park dam. The resistance was based upon losing a beautiful natural area, but more importantly the environmental movement led by the Sierra Club and its Executive Director, Dave Brower was loath to allow the precedent of a dam being built in a federally protected national monument. The Echo Park project was defeated in part by an effective grass-roots effort impacting congressional attitudes topped off by a congressional hearing during which Dave Brower effectively refuted the Bureau’s technical and economic claims. Finally, to seal the Echo Park deal, Brower and the Sierra Club agreed to withhold opposition to Glen Canyon Dam. An agreement that Brower made before he had seen Glen Canyon and one that he would regret for the rest of his career.
At the time of the battle over Echo Park, very few people had floated the Colorado River through the stretch that John Wesley Powell had named Glen Canyon. After surviving the maelstrom of Cataract Canyon, Powell and his battered companions found Glen Canyon to be a restful respite from the rapids they had endured and the ones still left to be run. Edward Abbey, the iconic southwest author floated the Colorado through Glen Canyon in a drug-store raft when the river was still wild. In his classic book, Desert Solitaire, published after the dam was complete Abbey mourns the loss of
pristine wilderness buried under the waters of Lake Powell, writing, “I was one of the lucky few...who saw Glen Canyon before it was drowned. In fact, I saw only a part of it but enough to realize that here was Eden, a portion of the original paradise.” The deep canyons of red sandstone with the tranquil river flowing past side canyons that hid treasures such as the Music Temple and Rainbow Bridge was little know when Glen Canyon Dam was approved. As the dam project moved ahead the trips through the canyon increased and environmentalists began to fight to stop dam construction and save Glen Canyon.
The last ditch effort to defeat Glen Canyon Dam was not only based on the desire to save a unique and beautiful ecosystem. Dam opponents raised other issues and highlighted deficiencies in the planned dam. They pointed out that water from Lake Powell would flood Forbidding Canyon to the base of Rainbow Bridge, which was protected as a National Monument, again raising the argument that dams and reservoirs should not infringe on federally protected land. Practical issues questioning the life and effectiveness of the dam were also raised. The Colorado is an extremely silty river, carrying more silt per cubic foot than the mythical muddy Mississippi. Those who opposed the dam pointed out that Lake Powell would fill with silt and drastically shorten the useful life of the dam. The anti-dam group, also put pencil to paper and computed that the evaporation loss from Lake Powell and Lake Mead would waste a tremendous amount of water and make it difficult for the Colorado to fill both reservoirs in all but the wettest of seasons. Despite the environmental, political and scientific arguments, the Glen Canyon Dam project had gained momentum and proved impossible to stop. In the end, recognizing defeat, Dave Brower, the Sierra Club and their environmental coalition turned toward fighting two additional dams planned within the Grand Canyon itself. These proposed dams, tentatively named the Marble and Bridge Dams were defeated, but the controversy around Glen Canyon continues to swirl in the desert southwest.
Construction on Glen Canyon Dam began in 1956 with a ceremonial telegraph from President Eisenhower. Located 15 miles upstream from Lee’s Ferry Arizona, the design of Glen Canyon Dam is similar to Hoover Dam, using an arch to transfer the weight of the water into the canyon walls and floor. Unlike Black Canyon the site of Hoover, where the igneous rock was relative hard and strong, the porous, weaker Navajo Sandstone of Glen Canyon required engineers to design a heavier arch. The greater mass of Glen Canyon Dam would by sheer weight help the arch hold back the waters of Lake Powell by increasing the surface area of the dam in contact with the canyon floor and walls.
Built by the Bureau of Reclamation and primary contractor Merritt-Chapman & Scott the dam was dedicated in 1966. Like Hoover, Glen Canyon was constructed in a series of columns that were cooled by refrigerated water and grouted together. In total, the dam contains 4.9 million cubic yards of concrete. Standing 710 feet from its bedrock foundation the dam has a crest length of 1,560 feet, a base thickness of 300 feet and a crest thickness of 25 feet. The dam cost $135 million, claimed eighteen lives and contributed to the eventual bankruptcy of Merritt-Chapman & Scott.
Construction of Glen Canyon
Dam showing individual columns
Like Hoover, Glen Canyon Dam incorporated bypass tunnels bored during construction into the spillways. The spillways start near the top of the Dam, drop sharply before hitting the bypass tunnels where the grade flattens out forming an elbow. Combined, the two spillways, each 41 feet in diameter, allow 276,000 cfs of water to bypass the dam.
Schematic of West Spillway Tunnel
In addition, to the spillways, Glen Canyon Dam was able to pass 30,000 cfs of water through eight penstock pipes fifteen feet in diameter. The penstocks fed eight gigantic turbines which are able to generate 1,021,248 kilowatts of power every hour. Four, eight foot diameter bypass tubes allowed an additional 15,000 cfs of water to flow through the dam. With spillways running at full capacity, all eight penstocks open and the four bypasses flowing, a theoretical total of 321,000 cfs of water can be moved from Lake Powell, through Glen Canyon Dam to the river below.
East spillway discharge and flip bucket
Glen Canyon discharging from east spillway and outlet pipes
Impounded behind Glen Canyon Dam, Lake Powell is the second largest reservoir in the country. It stretches 186 miles north into canyon country, has 1,900 miles of shoreline surrounding a lake surface of 254 square miles. The lake holds 27.0 million acre feet of water. Before dam construction was complete the bypass tunnels were closed in January 1963, beginning the process of filling Lake Powell to capacity. The lake took 17 years to fill, reaching an elevation of 3,700 feet above sea level in 1980. Water level in the lake fluctuates due to the volatile cycle of drought and flood common in the American west. Today Lake Powell is at 43% capacity holding 11.7 million acre feet of water.
El Nino 1983
Periodically, a band of warm water develops in the Pacific Ocean off the western coast of South America. Known as El Nino, this temperature anomaly drives changes in the weather throughout the western hemisphere and brings intense winters and high precipitation to the western United States. The winter of 1982/83 delivered a historic El Nino.
The operators of dams in the American west walk a tight rope each spring. To maximize both water storage and the production of electricity, dam managers have an incentive to maintain the highest reservoir levels possible, while leaving space for anticipated spring runoff. To successfully accomplish this balancing act they depend upon the hydrologists of the Colorado Basin River Forecast Center (Forecast Center) based in Salt Lake City. To project spring runoff, the Forecast Center uses complex computer models that take into account the snowpack, temperature forecasts and historical data to project the amount of runoff that will be fed into each river drainage. This information is provided to the Bureau and its dam operators who make decisions about how much water to discharge from reservoirs to provide ample headroom for runoff while maximizing storage and the production of electricity. When calculating how far to draw down their reservoirs, operators must also consider information specific to their dams. Spillway and bypass capacity, efficient water levels for the production of electricity and elevation of the penstock openings all come in to play for each dam and reservoir. In addition, each operator must consider the capabilities of upstream and downstream dams and coordinate with their operators to insure that an entire river system is working together to smoothly move water downriver. The accuracy of Forecast Center models are dependent on the weather patterns following predictable cycles based upon history and experience. The events during the spring of 1983 would test and destroy the assumptions that drove Forecast Center models.
The storms that El Nino unleashed on the western states began during the second half of January 1983. First making landfall in California, they tore at waterfront homes, destroyed Santa Monica Pier and buried the Sierra Nevada in snow. Echo Summit near Lake Tahoe recorded 62 feet of snow. Farther east, the storms forced the Great Salt Lake to rise by four and a half feet and moved into the Rockies where ski resorts reported snow depths of 68 feet. After the initial onslaught in February and March, the overall snowpack was 14% above normal and then began to slowly melt. In April, the snow pack in the Rockies increased again and cold storms in May not only added snow but delayed warm weather and prevented a gradual melt. At the end of May, everything changed. The cold snap was replaced by temperatures in the 80’s throughout the Great Basin, releasing the snowpack from its slumber and sending torrents of water into the Colorado River system. This onslaught of water was above and beyond the experience of the Forecast Center, forcing them to create new projections every seventy-two hours, projections that due to the limitations of their models and insufficiency of their raw data led to faulty decisions by Bureau officials who were struggling to catch up with rapidly unfolding events.
Historical records indicate that peak spring discharges on the Colorado of 120,000 cfs were not uncommon, with recorded floods of 170,000 cfs in 1921 and 240,000 cfs in 1884. Analysis of flood residue from the distant past suggest that during the last forty-five hundred years, the Colorado has reached 340,000 cfs several times and once approached 500,000 cfs, or roughly the discharge of the Mississippi River.
The 1983 Flood
The spring of 1983 would not reach these historical flood levels, but the deep snowpack and the speed that the melt occurred made this the biggest challenge in the Glen Canyon Dam’s twenty year history and found the Bureau unprepared. By the end of February the Bureau had emptied Lake Powell to a level that allowed one million acre feet of headroom. As the first of the massive snow melt hit in March, the reservoir began to rise at one inch per day, despite full discharge through the bypass tubes and the penstocks. In mid-April the water level dropped, but resumed climbing again on April 22 raising one-half inch a day until June 1, when the lake had reached a point less three inches below the top of the spillway gates. On June 2, the Bureau made the decision to open the spillway gate on the eastern bank. The east and west spillways combined discharge are adequate to protect Glen Canyon Dam against all but the worst of historical floods. Each spillway is 41 feet in diameter, drops 500 feet and skirts the dam abutments. Near the bottom of the tunnel, the spillways flatten out as they meet the old river bypass tunnels. The upstream end of the bypass tunnels had been filled with a concrete plug to keep water from working backward toward the dam’s foundations. When the water reaches the river at the bottom of the spillway it is traveling 120 miles per hour, hits a concrete flip bucket and shoots into the air in a huge plume of spray and mist that fills the narrow canyon below the dam. Dam managers prudently lifted the spillway gate only slightly on June 2, watching and listening for signs of trouble, well aware of the incredible power generated by the falling water. Initial indications were that the spillway was performing, so the gate was opened another two inches and plans were made to open the gate even further on Monday, June 6.
At midnight on Sunday, June 5, an assistant dam operator descended into the depths of Glen Canyon to perform a routine inspection in the tunnels that interlace the dam. An important part of these inspections is to listen for noises and sense vibrations that are outside of the norm, hoping to catch and fix problems before they become major. In the early hours of Monday morning, June 6, the operator arrived at the eastern abutment of the dam, where he began to hear an unfamiliar sound. The noise was soft, but listening carefully he began to hear a deep rumbling sound coming from within the eastern canyon wall. The sound was not continuous and there would be silence, followed by a series of booms, calling to mind a rock tumbling along a creek bed. Alarmed and worried the operator called his supervisor, Dick White, who came immediately to the gallery that overlooked the eastern flip bucket, where he was joined by Dam Manager, Tom Gamble. As the sun began to rise, a dark object flew out of the eastern spillway, hit the flip bucket and catapulted into the river. The object appeared to be large, perhaps weighing hundreds of pounds. The discharge of the spillway should have been an unbroken flow of water, but as Gamble and White watched they saw that water was exiting the spillway in a series of blasts, that were pushing out a great amount of water mixed with concrete, gravel and twisted rebar. It was obvious to the men that the water had begun to tear apart the tunnel, but even more alarming was that the water was red, indicating that the water had broken through the concrete and was eroding the Navajo Sandstone of the canyon wall. Tom Gamble ordered the spillway gate closed and placed a call to the Bureau’s Engineering and Research Center in Denver.
The knowledge that the eastern spillway at Glen Canyon Dam was disintegrating sent the Bureau into action, immediately dispatching Phil Burgi, the manager of the Bureau’s Hydrology Lab to assess the damage. This required that Burgi be lowered into the spillway tunnel in a small wheeled wagon controlled by a winch and cable. Once he had viewed the damage, he would than be winched back to the top to deliver his report. In the best of times, riding a metal cart into the steeply inclined tunnel would be a daunting task. The current circumstances made it more harrowing. Lake Powell was being held out of the spillway by two radial gates each weighing 174 tons and with the reservoir at record levels the lake surface was less then three inches below the top of the gates. As Burgi was lowered into the tunnels, it would have been easy to imagine a gate failure, a rapid and rough ride down the tunnel, over the flip bucket into the air, ending up in the cold Colorado.
Ten minutes into his ride and close to the elbow where the spillway met with the old bypass tunnel, Burgi stopped the cart and stared at a series of ragged holes in the spillway’s concrete lining. Searching further, he found above each hole a small bump or nodule in the concrete, a bump that would have caused the rushing water to jump and form air bubbles, unleashing a hydraulic phenomena know as cavitation. As Burgi continued down the spillway, each successive hole was larger and deeper until finally the cart’s progress was stopped by a cavity too large and with too much exposed rebar for the cart to pass. As he was pulled slowly to the surface Burgi speculated that if cavitation theory held true, there was a truly giant hole at the elbow allowing the water moving through the spillway to eat into the sandstone of the canyon walls.
Cavitation is caused when a rough surface forces free flowing water to jump or skip over a surface allowing air bubbles to enter the water flow. The high speed collapse of these air bubbles creates shock waves of incredible pressure making the water highly erosive. During Glen Canyon’s construction, care was taken to make the concrete in the spillway tunnels smooth, but even a relatively small nodule or irregularity in the concrete can cause cavitation. Once the air bubbles are introduced cavitation will leapfrog down the spillway causing ever-greater damage to the lower portion of the tunnels. Add the turbulence and erosion potential caused by the elbow between the spillway and recycled bypass tunnel and the potential for damage was staggering. In the years since Glen Canyon had been built, the Bureau of Reclamation had learned that by introducing air into the water using aerator tubes, the impact of cavitation can be mitigated. These aerators were introduced into spillways of the Yellowtail Dam in Wyoming after the Bureau observed cavitation damage, but the decision was made not to retrofit the Glen Canyon’s spillways with aerators.
Looking down into a Glen Canyon spillway
Phil Burgi emerged from the tunnel on Monday afternoon, June 6 with terrible news for Dam Manager, Tom Gamble; further use of the eastern spillway would risk erosion of the sandstone in the canyon wall, perhaps putting Glen Canyon Dam at risk. It was reasonable to assume that the western spillway, although still intact would suffer the same damage if a decision was made to open its gates. To complicate matters, the western spillway ran closer to the dam abutment, multiplying the risk of erosion in the western wall. With Lake Powell within inches of pouring over the top of the spillway gates and record snow melt rushing into the lake, Gamble had lost his most effective tool to pass the flood waters around Glen Canyon Dam.
With projections calling for Lake Powell to breach the spillway gates during the evening of June 7, a stopgap measure was drastically needed while the Bureau’s engineers analyzed their options. The dam’s maintenance crew arrived at a desperate, but innovative solution; plywood. Raiding hardware stores in Page, Arizona the crew bought all the pieces of four by eight, three-quarter inch marine grade plywood available. Starting at sundown on the night of the sixth and working between the cold water of the lake and a 52 foot drop off to the mouth of the spillway tunnel they began to weld together steel frames, attaching them to the top of the spillway gates. The plywood was than bolted on the frames, effectively raising Glen Canyon Dam by four feet. A very leaky four feet, as water found its way around and in between the joints of the plywood, but enough of a solution to provide the time for the Bureau to regroup.
As the engineers studied their options, the four bypass pipes began to leak at their expansion joints. Adding pain to misery, it was necessary to shut down the bypass pipes for repairs, further increasing the speed that the lake was creeping up the precarious plywood barrier. With their backs to the wall, the dam operators began to send a small amount of water down both the east and west spillways. Unfortunately, the combination of this limited spillway release, the water from the now repaired bypass pipes and the eight penstocks routing water through the generators, was not enough to keep Lake Powell from continuing to climb-up the backside of the dam.
The Bureau has always maintained the that integrity of Glen Canyon Dam was never in jeopardy during the flood, but in the first days of June 1983, in the midst of the crisis the workers and managers may have had a different view. With the spillways eroding at low discharge levels, concrete and rocks spewing forth into the river, the reservoir rising daily and the dam itself vibrating, it must have been conceivable for the men on the ground that the dam could indeed fail. Failure of Glen Canyon could have occurred in two ways. The first would be that the water would overwhelm the spillways allowing the water to rise and crest the dam creating a large waterfall raining down on the power station at the foot of the dam. This scenario would be dramatic and cause significant damage, but it was possible that the dam would survive, the waterfall subsiding as the spring runoff came to end.
The second failure scenario, although not as dramatic as a 700 foot waterfall pouring over the dam crest, was possibly more dangerous and could lead to permanent failure of the dam. If erosion of the rock below the spillways worked backward to the lake bottom, the dam could be breached along the sides. This breach would allow the entire lake to begin to wash through the fissure. The water pressure of the lake would drive ever increasing erosion that could rapidly turn a small opening into an uncontrollable stream of water leading to massive flooding. If this occurred the dam would be washed away or become useless, a large concrete monument anchored in the middle of Glen Canyon with the Colorado River flowing around its sides.
If the dam was to fail rapidly, modeling estimated that the initial surge would be 520 high and travel downstream at twenty miles per hour. Navajo Bridge, downstream from Lee’s Ferry and 460 feet above the river would be washed away. The flood would roar down the Grand Canyon into Lake Mead, where the water would overwhelm Hoover Dam, reap destruction through the Colorado’s floodplain and continue to the Gulf of Mexico.
On Monday, June 13 with the water rising at a rate of five inches per day and the snow melt projected to continue, Bureau engineers in Denver made a decision to hold the western spillway at a low discharge and increase the flow through the damaged east spillway. The east tunnel, which had been drilled at a greater distance from the dam abutments and the lake bottom was going to be allowed to erode while protecting or holding the western tunnel as a backup. On Wednesday, June 15, the east spillway was opened further, bringing the dam’s total discharge to 60,000 cfs. This strategy appeared to be working until Saturday the eighteenth when discharge from the eastern tunnel began to surge intermittently. Water would shoot out in a continuous stream and then hesitate before coughing out a gulp of air. The cough would be followed by water and debris, again to be followed by a gasp of high pressure air. Deep inside the tunnel a pile of debris had accumulated causing water to back up in a wave, forming a water jump and allowing air and water to mix in a destructive combination. To blow out the debris and force the water to return to a less erosive continuous flow, the spillway gates were opened to the point where the east tunnel was carrying 20,000 cfs alone. This surge of water was successful, cleaning out the tunnel and allowing the spillway’s discharge to be dialed down. Unfortunately, this respite was temporary, on Tuesday night June 21, with the lake climbing to within four inches of the top of the plywood, the dam operators opened up the east spillway until the dam was passing a total of 70,000 cfs through the spillways, bypass pipes and penstocks.
When the operators opened up the spillways to allow 70,000 cfs into the Colorado, the Grand Canyon was filled with rafters. Boaters were making the trip in huge rubber motor rafts; called baloney boats, smaller oar rafts and wooden dories. Each trip consisted of paying customers and professional guides. The total number of people rafting the Canyon in early June was close to 1,300 in 213 boats as part of 38 commercial and 16 private trips. As water levels climbed during the early days of June the guides began to see a side of the Colorado they had never before witnessed. Rapids that were relatively harmless in the past began to sprout teeth, others were buried by the increased flow and disappeared. Water levels rose filling side canyons and covering beaches, the speed of the river doubled from three to six miles per hour and guides were forced to find new routes through rapids, discover new camping sites and moor their rafts and dories in unfamiliar locations.
In response to the increased discharge, the Park Service closed the river to new launches at Lee’s Ferry and began to drop waterproof and weighted notes from helicopters onto the beaches inside the canyon. The notes warned of the coming deluge and cautioned rafters to camp high. The flow of 70,000 cfs created monsters of some of the most famous rapids in the Grand Canyon and rafts trying to negotiate the rapids began to flip, tossing passengers into the swollen river. One of the most notorious of the Grand Canyon rapids is Crystal, created by a massive discharge of debris in 1966 out of Crystal Creek at river mile 99. Always a dangerous rapid, at 70,000 cfs, Crystal channeled a smooth tongue of water into a standing wave that was estimated to be 30 feet tall. On June 23, the standing wave at Crystal began to flip 35 foot long baloney boats, throwing multiple passengers and guides into the water. Unbelievably, no one was killed in these accidents, but on Saturday June 25, this changed when a small group misjudged the line around the standing wave allowing Crystal to claim a life.
A baloney boat flipping in Crystal Rapid, 1983
At 11:00 on Saturday night June 25, three experienced dory guides, Kenton Grua, Rudi Petschek and Steve Reynolds, quietly and illegally launched a wooden dory named the Emerald Mile into the roaring Colorado at Lee’s Ferry. Guides sleeping on their rafts, waiting for the Park Service to reverse its closure of the river, helped to push the Emerald Mile into the current and watched as Grua stroked the boat downriver and out of sight.
A legendary figure within the guide community, Grua and his boat-mates were determined to use the record discharge from Glen Canyon Dam to set a speed record for a trip from Lee’s Ferry to the Grand Wash Cliffs at the headwaters of Lake Mead. Taking turns rowing, running swollen and now unfamiliar rapids without the benefit of stopping to scout, they flew down the canyon arriving at mile 99 and Crystal at 9:30 in the morning on Sunday, June 26. Without stopping the Emerald Mile attacked Crystal and it’s standing wave head-on, rising vertically up its face, before tumbling back, capsizing and ejecting the three guides into the churning whitewater. Grua and Petschek were able to cling to the boat, while Reynolds who had leaned over the bowsprit as the boat climbed the wave took a bump on the head and went underwater twice for extend dunks before emerging and swimming to his partners. Together they righted the dory, gathered what gear they could and despite being dazed and battered continued their run, past the remains of overturned, destroyed rafts and through the remaining formidable rapids. Surviving all the challenges, the Emerald Mile emerged from the Grand Canyon at 11:38 in the morning of Monday, June 27. Grua, Petschek and Reynolds had run the entire 277 mile length of the Grand Canyon in 36 hours and thirty-eight minutes beating the previous record by ten hours.
Ken Grua relaxing in the Emerald Mile
Grua rowing into the non-flood standing wave in Crystal Rapid
Shortly after the Emerald Mile completed its run, the Bureau reacting to forecasts that another runoff surge was headed for Lake Powell, opened Glen Canyon’s east and west spillways further, allowing a total of 92,000 cfs to escape from the dam. This release moved quickly down through the Grand Canyon, forever changing the landscape. In the case of Crystal, the surge swept away the piles of debris on the river-bottom and the standing wave fell from a thirty foot monster down to a manageable ten feet. The Bureau held the discharge at 92,000 cfs for thirty-six hours until upstream gauges showed that the worst of the melt was over. Based upon these reports, Gamble and his crew began to slowly close the spillway gates, monitoring the the water level, allowing the lake to rise while hoping to hold damage to the spillways at a minimum. With the lake falling below the bottom of the plywood flashboards, welders climbed out onto the top of the spillway gates and replaced the jury-rigged metal and plywood extensions with steel bulwarks. Finally, on July 15, the lake level peaked allowing Gamble to fully close the spillway gates, bringing the crisis to an end.
On July 23, Gamble sent men down into the spillways to assess the damage caused by the extended period of high water flows. What they found was shocking! The concrete lining in each spillway was eaten away and the damage descended deep into the underlying sandstone. The destruction was the most pronounced and the most disturbing at the elbow where the spillways met the old bypass tunnels. Gamble, knowing that the spillways would have to be ready for the not too distant spring of 1984 began repairs immediately. This time the Bureau’s engineers concentrated on the smoothest concrete finish possible, but also on installed aerator tubes to help eliminate the damage caused by cavitation. These repairs, costing $32 million or 27% of the cost of the original, dam were completed in time for the 1984 runoff season.
Damage to the east spillway, 1983
Glen Canyon Dam had faced the threat of flood and survived. The Bureau of Reclamation in it’s video “The Challenge at Glen Canyon Dam” spins the crisis as an unavoidable and unforeseen natural catastrophe dealt with efficiently by courageous and heroic men. A portion of this is true. Once the Bureau found itself in a crisis, the men on site performed in an innovative and creative manner. The men who built the plywood flashboards, Burgi’s trip down the east spillway and all those who worked long hours under stress had performed heroically. Where the Bureau failed was in the decisions made during the construction of the dam, their unwillingness to update the dam’s spillways and in planning for the 1983 snowmelt. The decision to use the existing bypass tunnels for a portion of the spillways was a cost cutting decision, not one based upon solid hydraulic engineering. The subsequent decision not to retrofit the spillways with aerators despite evidence of problems with Hoover and Yellowtail was also a glaring error. The worst mis-judgement, however, was the Bureau’s limited drawdown of Lake Powell despite the large snowpack that built up during the winter and spring of 1983. The Bureau maintains to this day that Glen Canyon Dam was never at risk, but one only has to remember to the plywood flashboards, view the photos inside the spillways after the threat was past and think about the desperate release of water without notice onto the backs of over a thousand rafters in the Grand Canyon to understand the desperation the dam operators were feeling in June of 1983.
The cost of the flood and near failure of Glen Canyon Dam are difficult to add up. In addition to the $32 million for repairs and the death in Crystal Rapid, the uncontrolled releases from Glen Canyon Dam forced the operators of Hoover Dam to open their floodgates causing economic losses in the Colorado’s flood plain and accounting for six additional downstream deaths.
Hoover Dam discharging during the flood of 1983
Despite the Bureau’s contention that Glen Canyon Dam was never at risk, David Keys, long time engineer with the Bureau of Reclamation and its commissioner from 2001 to 2006 was quoted in the Sacramento Bee in 1997, saying, “How close did we come to losing Glen Canyon in 1983? We came a hell of lot closer than many people know.”
Controversy continues to swirl around Glen Canyon Dam. Loss of environmental treasures, rapid siltation, water loss due to evaporation, damage to the riparian habitat in the Grand Canyon and the inability of the Colorado to fill both Lakes Powell and Mead in all but the wettest years fuel those who would like to see Glen Canyon Dam removed. Flood control, generation of electricity, recreation on Lake Powell and water storage drive the opposing view that Glen Canyon is an unquestionable benefit to the desert southwest. What is often forgotten is the lessons of the flood of 1983 and how close the Bureau came to losing Glen Canyon Dam.
Sources and References
- “A Story that Stands Like a Dam, Glen Canyon and the Struggle for the Soul of the West” by Russell Martin
- “Colossus, Hoover Dam and the Making of the American Century” by Michael Hiltzik
- “The Emerald Mile, The Epic Story of the Fastest Ride in History Through the Hear of the Grand Canyon” by Kevin Fedarko
- “Images of America, Glen Canyon Dam” by Timothy Parks
- “Desert Solitaire” by Edward Abbey
- “Beyond the Hundredth Meridian, John Wesley Powell and the Second Opening of the West” by Wallace Stegner
- “Colorado River Storage Project-Authority to Construct, Operate and Maintain” Chapter 203-Public Law 485
- “Dam Failure Study at Glen Canyon Dam” by Stephen E. Latham, Bureau of Reclamation Publication, July 1988
- “Beware the Bubble’s Burst, Increased Knowledge About Cavitation Highlights the Destructive Power of Fast-Flowing Water” by David Catchpoole,
- “The Dam Is Not Going to Break” by James Powell, University of California Press
- “The Challenge at Glen Canyon Dam” a video by the Bureau of Reclamation, www.youtube.com
- “Dam Details - Glen Canyon Dam” by the Bureau of Reclamation, www.usbr.gov