A deep drought has dropped the lake by nearly 150 feet in the last five years, leaving it less than half full. As the reservoir has receded, the red rocks have emerged again into the desert sun. Stunning formations with names like Cathedral in the Desert, archaeological sites and slot canyons have appeared after 30 years in watery seclusion. Side canyons like this one are once again open for miles of hiking not possible since Glen Canyon Dam, the last big water project of the West, was completed in 1963 and the Colorado River began backing up to create Lake Powell.

Up ahead, Chris Peterson hikes beneath an arched rock wall streaked with desert varnish. Peterson, now the executive director of the Glen Canyon Institute, an organization dedicated to draining Lake Powell, was among the first to discover that the rapidly falling water levels were unveiling treasures that hadn't been seen for decades.

I holler, asking if he's hiked this side canyon before. "No. My first time," he shouts back, the words echoing softly. "Probably the first time anyone has."

What Peterson means is we may be the first to hike through since the drought. We're certainly not the first. Before the dam, these sun-burnished red rocks were visited often by hikers, scouts (the trip was a final requirement for Eagle Scouts from Salt Lake in the late 1940s and 1950s), fishermen, and others. They came to see signature places with names that told of their epic grandeur, places like Rainbow Bridge, Music Temple, Hidden Passage, Forgotten Canyon, Hole in the Rock, Lost Eden, and Cathedral in the Desert, which the author John McPhee called the most beautiful spot in Glen Canyon.

Before the dam, this 200-mile stone trough was much as 1,200 feet deep in places, inspiring reverie from the days John Wesley Powell first led an expedition through here in 1869. Barry Goldwater floated the river in 1939, recreating Powell's journey, stopping here at Smith Fork to take pictures and fill canteens. The water, he wrote, was very good.

Novelists Edward Abbey and Wallace Stegner explored the canyon before and after the dam, extolling its lost virtues. "The canyonlands did have a heart, a living heart, and that heart was Glen Canyon and the golden, flowing Colorado River," Abbey wrote after the lake had filled.

The veins and arteries of that heart are side canyons like this one, laced with bridges, knobs, cool grottoes, potholes, amphitheaters, meandering streams and soft thickets of green cottonwoods, willows and tamarisk.

Peterson's assertion that we're the first here is symbolic of the feeling of joyous rediscovery that comes as we stumble over rocks and pad barefoot through soft stream beds that have been submerged for a generation. To get back here, our boat crept around bluffs of Navajo sandstone then weaved through a line of cottonwood skeletons, their trunks still submerged. While the water is low, it's not dropped enough to reveal some famous Anasazi petroglyphs near the mouth of Smith Fork.

Now, in this stream bed open once again to hikers, Wade Graham, a Los Angeles landscape architect and Glen Canyon Institute board member, and I walk from the beach where we've anchored our boat. The lake has been rising a foot a day thanks to an unusually large snow melt. Soon, this will be under water again, at least until the lake recedes in the fall and winter. The stream is cool, the sediment comforting on our feet as we head around a bend, the telltale white ring still high above our head. We wind our way upstream looking for a slot canyon referred to in a guidebook that Graham pulled out as we puttered down here from our wind-whipped campsite.

The stream bed gets drier as we progress. We find a small grotto where the other three in our party, including Peterson's brother, Brad, decide to spend the afternoon swimming. Later, they tell us the pool is filled with large crayfish.

Eventually, we catch up to Peterson, who points out a cottonwood that has reached about 12 feet tall. He'd promised the swift return of the ecosystem would be surprising and it was. Much of the sediment deposited by the lake had been washed out by the stream. Cottonwoods, willows and some tamarisk have grabbed hold. In the stream, we spot a frog, tadpoles and a fish we can't identify. We meet a couple and their dogs, who offer advise on the way ahead.

We find one dead end, culminating in a stagnant pool with a spectacular view of a dead cottonwood framing a rock knob. Up a ways in a dried mud stream bed thick with growth, we come across trees downed by beavers, who made a dam not long ago.

After we've passed the high water mark, we climb rock mounds, scrambling along a ledge, then across a sloping slick rock face and back down to the dry stream bed, the canyon continuing to close in on us. As we round one last curve, we come to the rock-strewn wash of the slot canyon, twin walls rising 60, 70 feet above us, sandstone streaked with desert varnish that looks like dripping burnt chocolate. As we follow the bend to the right, the slot narrows with the midday sun spotlighting the walls, and the rocks under foot give way to fluffy sand. Peterson and others have spoken of the reverence they felt entering these spaces and I now understand. The slot is quiet and magnificent, both eerily imposing and gently comforting.

"It's Grand Canyon scale here," Peterson had told me earlier. "It's so epic. It's America's lost national park."

To me, Glen Canyon doesn’t possess the overwhelming scale of the Grand Canyon. It’s more intimate while still evoking a sense of vast, timeless beauty. Stegner wrote that the province of the Grand Canyon was awe, while the province of Glen Canyon was delight.

Stegner correctly predicted Lake Powell would become "one of the great water playgrounds." "And yet," he wrote in 1969, "vast and beautiful as it is, open now to anyone with a boat or the money to rent one, available soon (one supposes) to the quickie tour by float-plane and hydrofoil, democratically accessible and with its most secret beauties captured on color transparencies at infallible exposures, it strikes me, even in my exhilaration, with the consciousness of loss. In gaining the lovely and the usable, we have given up the incomparable."

As Lake Powell's reach has receded, more and more of these intimate, incomparable places have opened to hikers and boaters once again. In Smith Fork, Graham has fallen behind, nursing feet sore from the previous day's adventure, when Peterson and I stop, sit beneath the arching walls and have a snack of cereal bars and water. It's about all the dry food we have left.

Peterson, 30, had hiked much of the Colorado Plateau from the time he was a teen, but he'd never been interested in the area around Lake Powell. He calls the reservoir a "black scar" on the map. Then in 2002, he hiked down the lower Escalante River, one of the lake's tributaries."I always wandered what the canyons were like under there," he says. "I knew the water was lower. I wanted to see some of these places I'd heard about." He was able to go about seven miles downstream from the confluence of the Escalante and Coyote Gulch. Two years later, he was able to walk 14 miles. He was stunned by the swift return of the vegetation and the animals. He saw birds, fish and cougar tracks.

"It is like you have explorer syndrome," he'd told me before our trip. "You're John Wesley Powell or some other early river runner seeing places that haven't been seen. You're witnessing a very rare and exciting point in history, witnessing this restoration. Nothing like it has occurred in the last couple of hundred years. It's very cool."

Peterson took pictures from his hikes to the Glen Canyon Institute and, after working as an intern, was hired as the nonprofit's executive director and pied piper leading the chorus calling for the lake's draining. In the last year, Peterson and other Glen Canyon representatives have been leading hiking and camping trips into the canyons along the lake.

He and Graham had been on one of those trips camping north of our hike near Hite for a couple of days before I arrive. When their boat's engine failed above a Class IV set of rapids that appeared thanks to the snow melt, Peterson hiked a couple of miles to cell phone range to call his brother for rescue.

After they pick me up at Bullfrog Marina, we motor -- slowly at times in the wind and chop -- a couple of hours north to find Peterson and Graham on a small island next to Fort Moqui, an uncovered Anasazi dwelling. The lowered water has exposed a signature carved into a rock on the island: "John Powell 1872." That's the date of Powell's last expedition, though it's impossible to know if the marking is authentic.

They'd grown impatient -- Peterson isn't the kind of guy to sit around -- and decided to shoot the rapids in their inflatable raft without an engine or paddles. The boat flipped, ending up on the side of the shore with a sheer cliff. So they had to use a kayak to ferry their gear across a ferocious current and camp in the open. Fortunately, one of the few things that remained dry were their sleeping bags.

By the time we reach them it is late in the day, so we cruise for a friendly shore as the wind whips up rollers. We settle on a cove on the lee side near Traychyte Creek with views of massive red rock formations.

We unpack our gear and then Peterson, Graham and I get in a quick hike up a portion of Traychyte Creek, where Peterson points out coyote tracks. Back at camp, he cooks refried beans, onions and peppers for burritos. We set our sleeping bags on rocks and packed sand that had been underwater for decades. The wind is relentless, though, and none of us sleep well.

Still, the night provides a contrast between the past and the present -- and perhaps the future. The past was the muddy Colorado River coursing through the canyon, carrying hikers, campers and river runners on rafts or boats. Our trip is a glimpse of the past -- hikes up tributaries, campsites on desolate stretches of the canyon.

After the river became a reservoir, houseboats and speedboats proliferated. Two generations of Westerners have grown up using Lake Powell as a giant water park, skiing, clowning off slides on the back of houseboats and cruising in relative luxury. The number of visitors peaked at nearly 3.6 million in 1992, was more than 2.5 million in 2000 and dropped to 1.8 million last year as the lake receded. Two of the five marinas on the lake have been closed and the park service and marina operator have spent millions pouring concrete extending boat ramps to the new water level and relocating marinas. In addition to recreation, Lake Powell provides water storage upstream for the larger Lake Mead, which supplies water to 18 million people in California, Nevada and Arizona.

When Graham and Peterson gaze into the future, they see the lake slowly draining. Most years, more water is flowing out through releases required by law and evaporation than is flowing in. Water would be more efficiently stored in underground aquifers, they say. And while the big spring snow melt eased the drought, the long term forecast is dry. "Lake Powell is going away," Graham says, though he admits he doesn't expect it to happen for perhaps 30 years.

"Mother Nature has made the decision for us," adds Peterson. He says the area’s economic model could change to promote river running, hiking and camping. Already, boat tours to unveiled attractions like Cathedral in the Desert have started.

Proponents of the lake, including groups like Friends of Lake Powell, argue that droughts come and go and that draining the lake would deprive millions of a stunning recreation spot. 

Peterson is unconvinced. After our boat weaves back through the dead cottonwoods to the main channel of the lake, I think of the sights we've passed during our two days meandering in these waters -- The Horn, Castle Butte, Forgotten Canyon, Tapestry Wall. Why not keep the lake at some lower level without draining it? I ask.

To Peterson, there's still too much hidden below the waves. "Is it the rocks that are beautiful or is it the lake?" he asks. "I say what makes Lake Powell beautiful is Glen Canyon and we're only seeing the tip of the iceberg. If it's the rocks that make it beautiful, then let's see more rocks."

It may be years before we’ll know whether rocks or water will win the long battle for Glen Canyon. In the meantime, the drought offers a rare moment to enjoy both.

Jim Morrison once slept overnight 240 feet high in a giant redwood while reporting a story for Smithsonian. He puts his Glen Canyon adventure high up with that one.