Too Much Dam Hubris...Lake Powell and the Future of the Colorado River

The Colorado River is a wonder of nature. Starting from glacial cirques high in the Rocky Mountains, the river flows through one canyon after another, culminating in the grandest canyon of them all, the Grand. For 1,450 miles, the river is a corridor of life, and webs extend out in numerous directions, providing life in some unlikely locations, like Las Vegas, Los Angeles, and Phoenix. Irrigation from the Colorado grows vast amounts of crops in desert valleys throughout the southwest.

The river has exposed an incredible geological story, and has played an important part of my life in my development as a teacher and geologist. It was a catalyst in my own life as I explored a corner of it on my first geology trip, and more recently as I floated a raft through the Grand Canyon for the first time last summer. So it is that I feel a little bit of ownership of the river (along with about 35 million other people).

I first became aware of the abuse of the river system as a teen when I came into possession of a dogeared copy of On The Loose, by Terry and Renny Russell, which was in part a eulogy for the canyons that disappeared beneath the stagnant waters of Lake Powell, backed up behind Glen Canyon Dam. I had grown up learning of the giant mega-dams as the greatest achievements of mankind (did anyone else get taught "Roll on Columbia, Roll on" while in grade school?), and I was duly impressed when I saw Lake Mead and the newly completed Glen Canyon Dam when I was a child on vacation. I started to learn that there were more issues at stake in regards to these giant mega-dams. Yes, flood control. Yes, cheap renewable clean energy. But at the cost of the some of some of the most amazing scenic canyons in existence, and at the cost of an entire river ecosystem. I know that those arguments don't hold much sway in a capitalistic society that measures the value of something in dollars earned. The thing is, the main purpose of these dams is imperiled by changing climate. One has to wonder if they were a gigantic mistake in the end. Do the benefits truly outweigh the costs?

One of the most incredible stories of Glen Canyon Dam is that it came perilously close to failing during an extraordinary runoff event in 1983. I've covered this story in the past, but it bears repeating (especially if you not familiar with it). Instead of using floodgates and spillways at the top of the dam for emergency drainage, designers utilized the diversion tunnels used to channel the Colorado River around the dam site during construction. They proved woefully inadequate to the task in 1983 as cavitation caused the walls of the diversion tunnels to rip out. In places the powerful flow of water cut 32 feet (10 meters) into the soft Navajo Sandstone and threatened the structural integrity of the dam itself. The diversion tunnels had to be shut down, and the lake threatened to flow over the crest of the dam in an uncontrolled fashion. This could have led to catastrophe, as such uncontrolled flow could have eroded and weakened the sandstone abutments of the dam. Failure of Glen Canyon dam would have led to the domino-like destruction of other large dams downstream, and the decimation of the water-supply infrastructure of some thirty million people. The disaster was averted by the construction of an 8 foot high dam of wood flashboards that held back the water long enough for the flood to subside. The structural integrity and survival of the dam came down to about one inch...the distance between the water level and the top of the flashboard dam in 1983.

There is an inherent conflict between water storage for irrigation and energy production, and flood control. One requires a reservoir to be mostly full; the other requires sufficient storage space for unusual events like those of 1983. The conflict requires a balancing act on the part of the water masters. Getting the balance wrong can lead to catastrophe downstream.

The scary part is that the 1983 event was not actually all that unusual. It happened because of a lack of storage space in the reservoir at the time (it had filled for the first time ever in 1980). The flooding involved flows of over 111,500 cubic feet (3,160 m³) per second. This was statistically a 25-year flood, one that has a 4% chance of occurring in any given year. Unfortunately, the statistics that guided the design of the dam have been called into question because of analysis of flood deposits upstream near Moab, Utah. New research suggests that there have been more than 40 large floods in the last 2000 years. Of these, 34 exceeded floods expected to strike once a century (20 would be expected under the old models), and 26 were larger than the so-called 500-year flood (only four of these would be expected under the prevailing models). Two of the floods were monsters that exceeded the design standards of the dam, even with the enhancements added after 1983.

At the other extreme of dismal news is the ongoing drought, 13 years and counting. The lake is hovering around 50% of capacity, and is expected to rise only modestly this year despite good snow conditions in the Rocky Mountains. We may be at the point where we are depending on the occasional El Nino event just to maintain a usable amount of water in the reservoir. There are some who think the reservoir will never have enough runoff to ever fill again.

All in all, this calls into question the wisdom of trying to control such a variable and unpredictable river. And we haven't even dealt with the question of sediment infill. The giant mega-dams are filling with silt at an astounding rate that is shortening their useful life. Ultimately our gigantic engineering projects will give way and the river will once again be in control. It's happened before with gigantic lava flow dams and blockages like Hoover Dam and Glen Canyon Dam will also give way.

Such were my thoughts as I stood on the hilltop overlooking this "mighty work of man". We hit the road again, headed towards Grand Staircase-Escalante National Monument, the largest single park on the Colorado Plateau.

Thanks to Wayne Ranney over at Earthly Musings for the heads up on the recent Colorado River research!

Tse' bighanilini and Hasdestwazi, "the place where water runs through rocks", and "spiral rock arches."

Glen Canyon was a beautiful, magical place that was unceremoniously flooded under the waters of Lake Powell (and I'm pretty sure John Wesley Powell would have been appalled that his name was given to the lake). Despite the gigantic eyesore of Glen Canyon Dam, there are some incredible places to explore in the immediate vicinity. One of them is Antelope Canyon, one of the Tribal Parks managed by the Navajo Nation. The two parts, upper and lower, of the canyon are called Tse' bighanilini, which means "the place where water runs through rocks", and Hasdestwazi, or "spiral rock arches."

Natural arch within Lower Antelope Canyon

Each of the canyons is worth a look. The upper canyon is justly famous for the noon hour beams of sunlight piercing the near total darkness of the deepest passages. It is also level from one end to the other. But it also requires a ride from town that includes an unbelievable race up a pure stretch of loose dune sand. And it is crowded, especially during the aforementioned noon hours when you might find yourself standing shoulder to shoulder with hundreds of other people. It's not a place for the claustrophobic.

On our recent tour, we opted for the lower canyon. It doesn't have the piercing beams of sunlight, and it is not level, requiring steps and ladders for access. But you don't have to be ferried up Mr. Toad's Wild Ride, and it tends to be far less crowded (in my three trips, anyway).

The tours of these incredibly beautiful works of nature begin beneath the shadow of the monstrous coal burning power plant just outside of Page. The coal mines are sixty miles away, but the energy infrastructure is here near Glen Canyon Dam. We were given a short safety lecture before walking down the end of the lower canyon.

It's hard to believe that such a treasure lies hidden in these folds of crossbedded Navajo Sandstone. The canyon is more than a hundred feet deep in most places, but only a few feet wide at the top. The guide politely asked us not to jump across the top of the canyon, prompting me to wonder what story was behind that rule...

Antelope Canyon drains an area of dozens of square miles, but the rushing waters of the occasional flash floods are forced to cross two ridges of Navajo Sandstone. The rock is cemented well enough to form vertical cliffs, but at the same time the sandstone is easily and quickly eroded by fast-moving sediment rich water. The result is an incredible labyrinth of looping and curving channels.

The natural curves of the canyon are accentuated by the crossbedding of the Navajo Sandstone. The Navajo formed as a gigantic sand dune sea that extended from Wyoming and Colorado to Nevada and eastern California. The crossbeds are the preserved slipfaces of the sand dunes. The dunes were present during the Jurassic Period, when dinosaurs wandered across what is now the southwest United States.

The narrow canyon can be dangerous. Storms that are dumping floodwaters upstream might not be visible from the parking lots. After a horrific tragedy in 1997 that caused the deaths of eleven people, rescue measures have been put into place, and tours aren't offered when rain threatens the headwaters region.

The canyon is full of abstract shapes and forms, and a photographer could wander for hours through the passageways (two hours to be exact, for an extra fee). Photography is allowed and encouraged by the guides, and they offer advice on shutter speeds and the like. It's been said that one can't take a bad picture here, but believe me, it's more than possible! The sharp contrast between light and dark wreaks havoc with photo framing. It challenging, but wonderful fun as well.

My favorite pictures occur where the sunlight is indirect and reflecting from above. The resulting yellow and golden hues are beautiful; the rocks seem to glow with inner light.

The texture and light are unique. If you are ever in Page, don't be afraid to put out the tour cost (between $20-35, with a $20 premium for those noontime tours in the upper canyon).

As is usual with my visits to the canyon, I have more pictures then I have words. Enjoy!

For the second time in my three tours through the lower canyon, our guide offered some beautiful flute music in the deepest part of the canyon. Here's the video:

Then it was time to go. We climbed up the last ladder into the blinding sunlight.

A Rock Outcrop, a River, and Sand flow into a Point Bar...

And the bartender said "is this some kind of joke?"

But it's not a joke of course, it's a simply stunning example of what happens when water flows over stone for a long time. What you are seeing here Horseshoe Bend on the Colorado River a few miles downstream of Glen Canyon Dam and Lake Powell outside of Page, Arizona.

A point bar is a real thing with rivers. When a river loops back and forth as a series of meanders, point bars form as sand ridges develop on the inside of the loop where the water flows more slowly. In the most technical sense, the sand bars in the picture above can be consider an example of the feature, although they are more familiar where rivers are flowing in flat floodplain.

It's obvious that Horseshoe Bend is no longer a flat floodplain! It may have been one at one time, but uplift of the Colorado Plateau (or the subsidence of the lands around the edge of the plateau) caused the river to speed up and start to erode downwards, forming an entrenched meander.

The approach to Horseshoe Bend is a sandy trail about three-quarters of a mile up from a parking lot about five miles south of Page on Highway 89. Although views are wide-ranging along the trail, there is barely a hint of the incredible view that awaits when one arrives at the brink of the cliff and looks down nearly a thousand feet to the river. Stunning is the only word for it.

My old camera couldn't show the entirety of Horseshoe Bend, so I was thrilled I was able to get these wider angle pictures with my new one. It's almost like looking at a petrified rainbow, although it should be said, this view is not entirely natural.

When Glen Canyon Dam was completed in the 1960s, the river was changed forever in terms of a human lifetime. Instead of the normal red silt-laden water, the river flows clear and cold (almost refrigerator cold, about 46 degrees; I can attest to this as I almost drowned in the river last year). As a result, green algae grows in the unnaturally blue river. It's beautiful to look at, but is kind of sad to consider what it should have been. Many of the native species of river life are in decline and cold-loving invasive species are thriving.

A trip-planning note just in case you are headed out to the region this summer: Highway 89 between Bitter Springs and Page was closed down by a serious slope failure along the Echo Cliffs Monocline. It may be years, if ever, before the highway will be repaired. In the meantime, the Arizona Department of Transportation has constructed a newly paved highway replacing Navajo Route 20. Although the detour is supposed to be temporary, I suspect it is permanent despite any feelings of the Navajo Nation about a new busy highway in a formerly isolated part of the reservation. There are far fewer engineering problems where the new highway crosses the monocline.

A Dam Big Shame, and Things Lost and Gamed...

A different "Paradise Lost"...

It just doesn't get much better than this, to stand on the brink of a high cliff in the barren desert, and to see a stream of life-giving water in the depths below. Of course, if you are in trouble and dying of thirst, you are pretty well screwed, since the cliffs are pretty much unclimbable! There is a story behind the dramatic appearance of the river in the photo. It not a genuine river anymore, not exactly. It is a blunt instrument, wielded badly.

Glen Canyon Dam was built between 1957-1964 after a contentious environmental battle over whether national parks (Grand Canyon – Bridge Canyon dam) or National Monuments (Echo Park dam-Dinosaur National Monument) should have reservoirs extending into their boundaries. Glen Canyon was at the time protected by neither designation. The dam is 710 feet high (216 m) and 1,560 feet (475 m) wide, with a volume of 5,370,000 cubic yards (4,110,000 cubic meters) of concrete. It is anchored in Navajo Sandstone. When full the lake is 186 miles (299 km) long, with 1,960 miles (3,150 km) of shoreline, and a total capacity of 26.2 million acre feet (equivalent of two years of the average flow of the Colorado River). The lake is a popular national recreational site today, but Glen Canyon was once one of the most beautiful valleys along the Colorado River. Unfortunately, when the dam was completed, only a few hundred people had floated down the river to see the stunning canyon (and therefore explaining my title of things "lost and gamed"; the dam was built here by threatening to put dams elsewhere).

After construction was completed in 1964, the lake slowly filled (since water use downstream did not cease, only surplus water was used to fill the lake) and did not reach capacity until 1980. In 1983, the dam came perilously close to failing due to a major flood and design errors. Instead of using floodgates and spillways at the top of the dam for emergency drainage, designers utilized the diversion tunnels used to channel the Colorado River around the dam site during construction. They proved woefully inadequate to the task in 1983 as cavitation caused the walls of the diversion tunnels to rip out. In places the powerful flow of water cut 32 feet (10 meters) into the soft Navajo Sandstone and threatened the structural integrity of the dam itself. The diversion tunnels had to be shut down, and the lake threatened to flow over the crest of the dam in an uncontrolled fashion. This could have led to catastrophe, as such uncontrolled flow could have eroded and weakened the sandstone abutments of the dam. Failure of Glen Canyon dam would have led to the domino-like destruction of other large dams downstream, and the decimation of the water-supply infrastructure of some thirty million people. The disaster was averted by the construction of an 8 foot high dam of wood flashboards that held back the water long enough for the flood to subside. The structural integrity and survival of the dam came down to about one inch...the distance between the water level and the top of the flashboard dam in 1983.

Dam engineers are confident that modifications to the spillway tunnels will allow the dam to withstand future flooding events, but other concerns have become prominent. The southwest has been suffering an extended drought, and lake levels in recent years have become perilously low, threatening to turn Lake Powell into a “dead pool” incapable of producing electrical energy. In 2013 the lake was filled to less than 50% of capacity. Some water experts suggest that the lake may never be able to fill to capacity again, in part from drought, climate change, and upstream diversions of water.

Back to that photo at the top of the page...it isn't the whole story. The spot is called Horseshoe Bend, and it lies just a couple of miles downstream of Glen Canyon Dam. It is an entrenched meander, which developed when the land was uplifted, while the originally sluggish winding river started cutting downward instead of laterally. The rainbow-like pattern of red rock and green-blue water is an artifice of the reservoir. Unlike the olden days when copious amounts of silt caused the river to flow red, the water draining from the lake today is transparent and cold, in the 40-50 degree range. For a river in a hot desert, this is extraordinary. The ecosystem of the river evolved in different conditions than this, and species are sensitive to the new regime. Natural species of fish, amphibians and insects are in a difficult situation. For we humans it is ironic that river rafters have look out for hypothermia in their crews if people get dumped in the river on a day when the temperature is over 110 degrees.

So the view is just stupendous, but sobering at the same time. It can be reached by a short 3/4 mile long sandy trail from a parking lot on Highway 89 just 4-5 miles south of Page, Arizona. The highway is closed because of a serious landslide farther south but is open to the parking lot. It is well worth your time if you are ever in the region.

Accretionary Wedge #36: How does life affect geology? Surviving on the Colorado Plateau

There was a day this home was abandoned. There was a day that something happened, a decision was made. Were they under attack? Did people die? Or was it a moment that a family knew the crops had failed, and there would be no food that winter? Or no more water in the nearby streambed? Were they called away to another place by a chief, or a shaman? Lots of questions, questions that are hard to answer. But abandoned it was, along with hundreds or thousands of similar homes in the region. Abandoned for hundreds of years before others came into the region.

Tourists seek out these former homes, and many of them remark on the permanence of these structures, still standing after 800 years. I look at them and I think of the permanence of stone, maybe, but also the transitory existence of people and populations. Before the decision to leave, generations of people had lived in these structures, and throughout their lives they never thought of being anywhere else. They didn't plan on enduring whatever catastrophe or threat that led to the decision to leave. But leave they did. There are lots of hypotheses, but I feel pretty strongly that they finally exceeded the capacity of the land to support human populations. That led to whatever else happened, I suspect.

Accretionary Wedge #46, hosted this month by Knowledge Flocs asks the question: How has life or civilization been affected by geology or how has geology been affected by life? I pondered this question essentially for the whole month before sitting down tonight and writing this. I was out there on the Colorado Plateau a few weeks back, and I almost mindlessly snapped a picture that I didn't give a second thought to. It was part of the view from the Wahweap Overlook at Lake Powell on the border between Arizona and Utah, and I was snapping a series of shots to get sort of a panoramic record of the view.

Tonight it caught my eye. A coal-burning power plant on the shores of an artificial desert lake. What is the carrying capacity of this land? There are thousands of people living in the immediate vicinity, but there are lines of copper wire leading out like a web to literally millions of homes in the wider region, especially places like Phoenix or Las Vegas. Looking at the coal-burning powerplant is to realize that the present-day population is depending on sunlight that fell on plants 70 million years ago to survive. They are depending on water that used to exist only in a deep inaccessible canyon. And to propel their vehicles they import the remains of plankton and one-celled organisms that lived by trillions upon trillions 200 million years ago in oceans and seas that don't even exist on Planet Earth anymore. Their food in large part is grown in other states or other continents.

And we take for granted that we will be living here permanently. We barely ever give thought to the intricate web of connections and imported energy that keeps this civilization alive. What happens when a piece of the web breaks?

I ask in particular because of that white strip along the shoreline of Lake Powell. It's the bathtub ring of the reservoir. It doesn't look like much from my lofty perch, but that is a terrifying lake level if you are one of the watermasters responsible for providing an allotment of water needed to keep things going downstream. The Colorado is the most important source of water in this arid land except for groundwater, which is pretty much non-renewable and is being used up in many areas. The region has been suffering through a decade-long drought, and global warming is leading to changes that may intensify the droughts for the conceivable future.

There are limits.That is the effect of geology on human life in this region. There is only so much water, and there is only so much coal. And populations and societies are not stable. Some will last longer than others, but the changes will come. Will we know when the limits have been reached and act? Or will we be caught off guard, and realize we need to move someplace else? And where will we go?

I'm appalled when I hear politicians say that the most important questions facing our generation have to do with the marriage of the gays and how important it is to de-fund Planned Parenthood.

Hidden Right Under My Nose: A gem outside Page, Arizona

It must have been so frustrating to be among the first Europeans to explore the Colorado Plateau, whether a Spaniard, a Mormon, or Mountain Man. It is so easy to get around on a vast plateau, because everything is so flat. Except that this is no normal plateau. Every time an explorer came to a river, it was almost always ensconced in a valley hundreds or thousands of feet deep, with vertical cliffs separating the travelers from the life-giving water below. Even worse, the deep canyons were a serious impediment to travel. Even as late as 1928, there was only one place where a vehicle could cross the Colorado River between Moab, Utah, and Needles, California, and that crossing was by ferry (Lee's Ferry to be specific).

The rivers were just as confusing for the first geologists who explored the region, like John Wesley Powell, Grove Karl Gilbert, and Clarence Dutton. To geologists who had grown up with well-integrated river systems like the Mississippi or Ohio, these western rivers made no sense at all. The rivers crossed mountain ranges, or entered mountain ranges, only to swing around and exit the mountain range on the same side. The general landscape would slope north, yet the rivers flowed in canyons that sloped south. Huge abandoned dry channels littered the landscape, with no rivers anywhere nearby that could have carved them. It was a puzzle to be sure, but the work of Powell, Gilbert and Dutton to try and solve that puzzle led to our understanding of many basic principles of geology, including graded streams, antecedent streams, superimposed streams, base level, and isostasy. But as hard as they struggled, they could not completely comprehend the history of the Colorado River. Even today we still don't have a complete picture of how this landscape evolved.

What we do know is astounding. For nearly a billion years, the earth's crust in this region has been near sea level and stable, but in the last few million years, that same crust was uplifted en masse some 2 vertical miles. Ancient rivers were rejuvenated, and new rivers formed as headward erosion tore away at the edges of the plateau. The entire river system that may have existed for tens of millions of years had been upended, and some rivers, the Colorado in particular, ended up flowing in a totally opposite direction of the original watercourse. The old meandering rivers were trapped in their channels as the land rose, so they cut straight down, maintaining the original river loops in what are called entrenched meanders.

We were in the vicinity of Lee's Ferry during our reconnaissance journey last week. I was looking for interesting stops to add to our AAPG field seminar in July (a trip you are welcome to consider joining!). A volunteer at the Navajo Bridge Visitor Center pointed out that I might want to check out Horseshoe Bend outside of Page, Arizona. I have to admit I have never really explored Page all that much. I never got a chance to see the original Glen Canyon, and neither did anyone else except the few hundred people who had rafted the river through the canyon by the time that Glen Canyon Dam shut the floodgates in 1963. It was apparently one of the most beautiful river canyons in the world, but it now lies beneath hundreds of feet of stagnant water and silt. Page was the town where the dam workers lived during construction, and to me it represented everything that was wrong with the choices we've made in land and resource use (the giant coal burning power plant on the outskirts of town doesn't help). And with the ongoing decade-long drought, the dam and reservoir are in danger of becoming totally useless as far as their intended use as water storage and power generation.

I walked the sandy three-quarter mile trail in the hot late afternoon sun, and reached the edge of the precipice. At this point, the Colorado River is flowing through a thousand foot deep gorge cut into the thick Navajo Sandstone. It is just a few miles downstream of Glen Canyon Dam, and a few miles upstream of the Echo Cliffs and Lee's Ferry where the river briefly flows along a stretch without cliffs. It almost immediately plunges into Marble Canyon, and the Grand Canyon. Taken in pieces, like the shot above, and the one below, the canyon is scenic, colorful, and spectacular. It is always stunning to stand on (or lie on, for the acrophobics) a thousand foot vertical cliff. But taken as a whole, Horseshoe Bend is special...

From the viewpoint at the end of trail, we are standing at the outer edge of one of the entrenched meanders, so we have the spectacle of the river running in a nearly complete circle. It's hard to photograph without a wide-angle lens, but it is an incredible sight.

I was there at one of the harder moments to take pictures, though. The late afternoon sun was directly ahead of me, and it had been a dusty day, so all my pictures have lens flares galore. I can certainly imagine a serious photographer spending an entire day at this one spot, catching all the moods and sun angles.

Horseshoe Bend is accessed along Highway 89 just a few miles south of Page, Arizona. There is a parking lot on the west side of the highway. The hike is just 1.5 miles round-trip, but it is almost all in loose sand. Take water!