You can drown a river. They did so to one of the greatest of the world’s rivers, and now you can rent a houseboat and float hundreds of feet above what was once the high water of the Colorado, whose bed lies buried nearly 200 miles under the weirdly named Lake Powell. Weird because 19th-century explorer John Wesley Powell was the first great evangelist of the West’s water scarcity, and this lake just upstream of the Grand Canyon that isn’t a lake but a reservoir comes out of a moment that thought it could cheat nature, cheat fate, cheat Powell’s prophecies, and control the river.

Tens of thousands of boaters visit Lake Powell annually for petroleum-based outdoor adventure. So did we last spring, though my collaborators, the photographers Mark Klett and Byron Wolfe, and I had a specific purpose: to think about time, place, climate change, and possibility in this fraught and loaded location. What is the right way to feel when you’re floating across damage? It’s hard to know, when the light is as beautiful as it was last spring, when the two photographers and I searched for the lost landscapes Eliot Porter photographed for his 1963 book, The Place No One Knew: Glen Canyon on the Colorado.

The Colorado River seems like time itself when you float down it on the undammed stretches below Glen Canyon Dam. If you know the tremendous power of the free-flowing river, the water trapped behind the dam in the misnamed Lake Powell feels stagnant, paralyzed, static. And its ever-fluctuating levels are reminders that government engineers control the reservoir. When the water rises, shoreline saplings die. When the water falls, clams die. The unstable shoreline is a landscape of infidelities and a graveyard, full of small betrayed dead things.

The rise and fall of the waterline is marked more dramatically on the canyon walls, the infamous bathtub ring of Lake Powell, which rises and falls depending on how much water or electricity people want downstream. If you look at Lake Powell carefully, it’s disturbing – disturbing that the other half of the red rock landscape you’re looking at is underwater.

We found one of Porter’s locations bisected by water, the upper half still visible, the lower half submerged. It’s unsettling to look at a field of lithic fragments from the original canyon inhabitants and know that they were dropped hundreds of feet farther from the shore of a river than they now are from the reservoir. Or to take a powerboat up a slot canyon that before the 1960s you walked up. What lies beneath, and when will it reemerge?

The conflict over the fate of Glen Canyon, now sunk beneath the waters of the reservoir for the last 200 miles of its length before the dam, was one of the great environmental battles. The Sierra Club lost it, but the effort transformed the group from a western hiking club with conservation interests into perhaps the first modern environmental organization. Earth First! announced its birth with a symbolic action against the dam in 1981. Edward Abbey railed against it again and again and sent his characters to blow it up in the novel The Monkey Wrench Gang. The Glen Canyon Institute exists to see it undone.

The dam is all kinds of failure. It’s silting up. It was supposed to store excess water, but it turned out the Southwest was so thirsty there isn’t a lot of excess. And the evaporation the environmentalists battling the dam in the late 1950s promised is real. In fact, when this is added to seepage into the porous sandstone below, Lake Powell loses as much as 750,000 acrefeet annually, according to the Glen Canyon Institute – greater than what the City of Los Angeles uses in a year.

The dam’s future is an open question. We know now that dams are mortal, but the people debating the dam half a century ago, whether for or against it, didn’t foresee how mortal it would be. And they didn’t imagine the role climate change would play in dooming it. Scientific studies indicate that within the next 30 years, thanks to less rainfall, more evaporation, and unceasing demand for water, Lake Powell and Lake Mead downstream are in danger of hitting dead pool. That’s the point at which the water is so low it doesn’t turn turbines and generate electricity. We can decide to revise the fate of the river, and shorten the time until the river itself is back in control and the ecology returns to something a little less distorted. The Colorado has cut a mile deep into rock a billion years old. In the long run, the river that carved out the Grand Canyon is not going to be stopped for good by a plug of concrete several hundred feet high. Just give it time.

But it could be liberated sooner.