As the lake recedes, will they stampede?

In A PANORAMA OF SNOWY SLOPES, STILL WATER AND MUD flats, I stand on a grassy ridge, eye to eye with a furry mammal that outweighs me by half a ton and once played a starring role on nickels. He is drinking. I am withholding information.

Call him a buffalo, as most civilians like to, or call him a bison, as zoologists say we ought to. Either way he’s a big bull, brown fur rippling in the 35-degree breeze, indelicately slurping at a puddle. He comes up from his drink looking like an Allman Brother at closing time, all dripping whiskers and droopy eyes.

Tended by state rangers and their forebears, he and his forebears have lived here on 28,022-acre Antelope Island for more than a century, surrounded by the shallow waters of the Great Salt Lake, the largest lake west of the Mississippi. But unlike his parents, this buffalo could roam. If he only knew it, he could stroll right off this chunk of land, pad across the mud flats, trudge through a suburb or two and make his debut in downtown Salt Lake City society.

In other words, his island isn’t an island anymore. And the Great Salt Lake isn’t so great. A drought of several years has reduced it to less than half the surface area it covered just 15 years ago.

“The lake would be right here,” said Bruce Thompson, education director of the Friends of the Great Salt Lake, kicking at a patch of damp dirt near the lake’s south end as we began our tour one morning last week. Then he turned his gaze toward the horizon.

“It’s probably close to a mile out there now,” he said.

The lake’s waters, up to about 35 feet deep and laden with more than 4 billion tons of salt, still cover about 1,600 square miles, harboring vast quantities of brine shrimp and brine flies. On its busiest spring and fall days, this lake harbors as many as 5 million birds. It’s a startling experience to drive across the man-made causeway to Antelope Island, look out at the fowl-speckled, sky-reflecting lake on either side, and feel like a flea creeping across a crack in a vast mirror.

So what does it mean when the mirror is eventually interrupted by a mile or two of mud? We understand this about as clearly as my friend the buffalo does.

Last week, the lake’s level was 4,195 feet above sea level, having fallen seven feet since 1999. Most authorities blame the drought for most of this, but as Thompson was quick to point out, nobody in Utah is sure how much water from feeder rivers is being diverted to serve development. Nor is it clear what the lower levels mean for plants and animals.

“The lake has always changed. The lake will always change. And the birds change patterns with the lake,” said avian biologist John Luft of Utah’s Division of Wildlife Resources.

The avocets and black-necked stilts, which like to nest in marshland, have actually been gaining coveted ground as the lake recedes. But for the white pelicans and snowy plovers -- both species whose nesting areas are now more vulnerable to other animals -- these are uneasy days.

Already, the mud flats have tempted a handful of illegal off-roaders, whose tire tracks stand out clearly amid the otherwise blank expanses near Antelope Island. Applying their tracking skills to the tire marks, the island’s rangers have surmised that the trouble boiled down to four yahoos, who stopped doing doughnuts last month when some new fences went up. The most uncomfortable animals so far seem to be the humans engaged in the multimillion-dollar business of harvesting brine shrimp and selling them around the world as food for prawns. As nearly as the experts can tell, the brine shrimp population is doing fine, but with the water levels so low, the shrimpers’ boats can’t always get where they want to go. Antelope Island State Park manager Ron Taylor estimates that the shrimping fleet is half the size it was last year.

The last time the water was this low, in the early ‘60s, some scientists publicly warned that the lake could vanish altogether. Instead, the weather changed. By the late 1980s, a series of wet years was sending so much water into the lake that Interstate 80 was threatened and the governor had to spend more than $71 million on a trio of massive pumps to send water into the western desert. Now the pumps sit idle.

On the lake’s north shore, an even stranger apparition stands in the shallows. In 1970, 32-year-old avant-garde artist Robert Smithson chose that spot, where the algae-tinged pink hue of the water reminded him of blood, for an immense earth artwork. By his design, a mystified team of tradesmen arranged piles of black basalt rocks in a 1,500-foot-long, 15-foot-wide curlicue. Smithson titled it “Spiral Jetty.”

But Smithson didn’t count on the lake’s variability. By the time he was killed in a plane crash three years later, “Spiral Jetty” was already vanishing under the rising waters. For close to 30 years, it remained under water. Now “Spiral Jetty” has reappeared. As for those bison, none have gone AWOL yet, perhaps because life is pretty good. Their freshwater springs remain wet, and their fertility rates and longevity are good enough that the state park’s wildlife ranger counted about 670 head during a roundup two weeks ago, about 170 above the herd’s target size. To keep the population in balance and raise some revenue for the park, rangers will sell most of those extra animals (some to ranchers, some to carnivores stocking winter meat lockers) and have issued half a dozen permits to hunters (at $1,105 to $2,605 each), who next month are expected to slay one bison each.

Hey, buddy. You with the dripping beard and the nickels in your history. If they come for you, I suggest you hit the mud at a full gallop. Then head north and east until you see a sign that says Yellowstone. Just don’t drink at that puddle they call Old Faithful. These mountain west waters -- you just can’t trust ‘em.

To e-mail Christopher Reynolds, read his previous Wild West columns and view his photos, go to www.latimes.com/chrisreynolds.