Quarter-full or three-quarters empty?
Looking at the up- and downsides of a disappearing Lake Powell

Unlike other dams, Glen Canyon does not provide any meaningful flood control. It doesn’t regulate streamflow to stretch out the irrigation season. And it isn’t so great at storing excess water because, well, there is no excess water. At best, it serves as an overflow basin for when Lake Mead fills up. But with both Lake Powell and Lake Mead holding only about 25% of their total capacity, the upper reservoir has become redundant – at least from a water storage standpoint.

It is from this redundancy that the Fill Mead First philosophy has emerged. Wouldn’t it make more sense, adherents of this school ask, to drain Lake Powell and put what water remains there into Lake Mead, so that you’d have one half-full reservoir rather than two quarter-full ones? So that you’d have billions of gallons of water evaporating off just one reservoir rather than two?

It’s a great question. And it brings up another one: Why Lake Powell? As in, what purpose does Glen Canyon Dam still serve in a climate-changed, diminished Colorado River world?

Let me start by saying that I believe the construction of Glen Canyon Dam was a crime against nature. It inundated countless cultural sites, killed 186 miles of the mainstem of the Colorado River along with hundreds of additional miles of side canyons and tributaries, and deprived everyone born after 1963 of the opportunity to experience one of our nation’s natural marvels. It radically altered the ecology of the Grand Canyon and further endangered already imperiled native fish.

Why was this sacrifice made? Primarily to enable the Upper Colorado River Basin states to comply with the Colorado River Compact.

The compact did two big things: First, it divided the assumed average annual flows of the river between the Upper Basin states (Colorado, Wyoming, Utah and New Mexico) and the Lower Basin states (California, Arizona, Nevada). The Lower Basin got 8.5 million acre-feet per year; the Upper Basin got 7.5 million acre-feet per year. Mexico was added later, getting 1.5 million acre-feet.

But there was something else: To ensure the Lower Basin would get its share, the Compact mandates that the Upper Basin “not cause the flow of the river at Lees Ferry to be depleted below an aggregate of 75 million acre-feet” for any 10-year period. In other words, the Upper Basin couldn’t merely take out its 7.5 MAF share each year and let whatever remained run down to their downstream compatriots. It had to deliver an annual average of 7.5 MAF.

That’s no problem during big water years, but during years when less than 15 MAF is in the river, the Upper Basin would have had to reduce its take accordingly, while the Lower folks would still get their share. During some dry years, the total flow of the river has been lower than 7.5 MAF, meaning the Upper Basin States would be left high and dry.

Unless they had a savings account. Or, in this case, a reservoir above Lees Ferry (Lake Powell) to store enough water in wet years to be able to release the Lower Basin’s 7.5 MAF during the driest years. If not for Lake Powell, the Upper Basin States would have been in deep doo doo over the past couple of decades, because they would have had to substantially cut consumption or go to war with California.

So you could say the Colorado River Compact’s downstream delivery mandate is the main reason we now are cursed or blessed with Lake Powell. It’s also perhaps the biggest hurdle for Fill Mead First folks to clear: You can’t really get rid of Glen Canyon Dam without scrapping the Compact, for better or worse.

The mandate and Lake Powell have another consequence: they force the Upper Basin states to count evaporation losses against their consumptive use of the river (because they have to deliver the 7.5 MAF after evaporation occurs). Meanwhile, the Lower Basin states can simply take their allotted share out of the river, regardless of evaporation: Another inequity baked into the system.

Glen Canyon Dam serves other purposes, too, such as:

• Silt control: Well, “control” may not be the right word, because no one has control over the clay and mud and sand (and other less savory sediments) carried down the Colorado and San Juan rivers. But Lake Powell does a good job of catching the silt and keeping it from continuing downstream to clog up Lake Mead. Silt was piling up in Mead at a rate of up to 137,000 acre-feet per year before Glen Canyon. Now it’s down to less than 10,000 acre-feet annually, thanks to that big silt-catcher upstream.

• Hydropower production: We’ve written about this a lot. The short version: If you did away with Glen Canyon Dam, you’d be depriving the grid of enough electricity annually to power about a quarter of a million homes in the Southwest. It would also drain between $100 million and $200 million annually from dam electricity sales, which helps fund endangered fish recovery programs. That said, by putting that water in Lake Mead, you’d offset some of those losses by increasing the generating capacity of Hoover Dam’s hydroelectric plant.

• Recreation: I will confess, when the Blue Ribbon Coalition announced its “Fill Lake Powell: The path to 3,588” initiative last year, I laughed. After all, the motorized recreation lobbying group was calling for massive consumption cuts by all Colorado River users not to save the river or keep the system from collapsing, but to keep Lake Powell boatable. That just seemed like some slightly lopsided prioritizing. But then a friend and Lake Powell lover called me out on it, and I do have to admit that I’ve done some recreating on Powell myself, and loved it.

The first time I saw Lake Powell was in the mid-1970s when the reservoir was still filling up. My parents’ friends had rented a houseboat, and we spent a week or so with them exploring side canyons, camping, swimming – which for me was floating around in my life jacket – in the warm waters, and hiking to out-of-the-way places that the reservoir and boat had made easily accessible.

There’s something surreal, even shocking about this vast body of water within an arid sea of stone. It’s easy to imagine someone heading off from their houseboat for a hike, getting lost, running out of water, and dying of thirst on a precipice hanging over a trillion gallons of water. It’s otherworldly in that it seems horribly out of place in this world, which maybe is why it played the part of a post-apocalyptic planet in the opening scene of “Planet of the Apes.”

But the otherworldliness is part of the appeal, I suppose. Over the years, I would return to Lake Powell with friends to camp out on the sandstone shores, sometimes getting there with boats, other times taking creaky old cars on sandy backroads to sections of shoreline that are now miles from the water. We spent a summer solstice or two on the reservoir, and it was so damned hot and the days so long that early each morning, I’d peel myself out of my sun-cooked and sweat-soaked sleeping bag and head straight for the tepid water.

It was usually a lot of fun: A luxurious change from the death march backpacking trips I tended to go on and a sort of novelty to be able to go on a big swim behind the Slickrock Curtain. Well, besides that time that some friends and I encountered a half-submerged cow carcass in the murky water near shore, its legs jutting skyward out of a horribly bloated body, Coors Light cans floating nearby like offerings to a bovine God. But, hey.

Back in 2006 or 2007, my wife, Wendy, and I headed to Powell for a different sort of trip, setting out from Halls Crossing in sea kayaks for a three-day tour. There’s something eerie about being right down in the glassy, dark water like that. When out in the main channel, I tried not to think about how those waters went down below me for hundreds of feet. I tried not to think about the story my cousins used to tell about how divers searching for one of the reservoir’s many victims didn’t find the body but did encounter 12-foot-long catfish in the depths. I tried not to think of what would happen if one of those monster houseboats crashed into me in my skinny little skiff. But all in all, it was a marvelous trip and a great way to see that part of the world. I’ve been plotting a longer journey ever since, one in which maybe we hitch a ride with a motor boat up the Escalante or something.

My experiences notwithstanding, recreation at Lake Powell is not only big business but has also become critical to the economies of the communities that have sprouted near its shores. A National Park Service study found nearly 3 million visitors to Glen Canyon National Recreation Area spent $332 million in and around the park in 2021 (down from $420 million in 2019 when reservoir levels were higher).

Page, Ariz., was established to house the workers who constructed Glen Canyon Dam and later became the park’s main gateway community, housing its employees, boats and businesses that cater to park visitors. When the Navajo Generating Station coal plant shut down in 2019, a lot of folks worried that Page would collapse, economically. But it has stayed afloat – pardon the pun – thanks in part to Lake Powell tourism.

If you drained Lake Powell, would tourism to the area dry up, too? I doubt it. Plenty of folks – myself included – would flock to the place to see what the actual canyon looks like, even if it is half silted over. Others, I’m sure, would want to witness the carnage of climate change-wrought collapse. Hell, I’d pay good money to be on a house boat as the reservoir drained just to see the place revealed in real time.

I suspect Powell will be drained or drain itself in the next few decades, but I doubt it will happen in the next few years. The Bureau of Reclamation is clearly intent on keeping reservoir levels viable for as long as possible, even if it means bringing the hammer down on the states and forcing cuts in consumption. Combine those efforts with a few good snow years and, who knows, the reservoir might just rebound somewhat.

The Land Desk is a newsletter from Jonathan P. Thompson, author of “River of Lost Souls,” “Behind the Slickrock Curtain” and “Sagebrush Empire.” To subscribe, go to: www.landdesk.org