Jon Bohach knows the frustration. As a longtime river guide, he remembers when rafting down the Rio Grande, with its roiling haystacks, was a wild adrenaline rush. Now, it's more like canoeing in a bathtub. In fact, if the boat goes over, all you have to do is stand up - and you won't even get your shorts wet.
A decade of drought and greater water use on the Rio Grande have been turning some stretches of the once-mighty river into dry gravel. In May, it stopped flowing in Big Bend National Park for the first time since the 1950s. "People call and ask about a raft trip, and you tell them, 'Well, the river is really low and canoeing is about all you can do on it right now.' Then you hear a click," says Mr. Bohach, his eyes hidden from behind sunglasses and a cowboy hat.
But tourism is not all that's hurt here in one of the nation's largest and most remote national parks. Plants and animals, which depend on the river, are also threatened. There are days when air pollutants from coal-fired power plants on both sides of the border create the highest concentration of sulfates and the worst visibility of any Western national park.
Operating with a budget shortfall of more than $6 million a year, Big Bend is routinely considered one of the top 10 most endangered parks in the US. Now, to help preserve it, park enthusiasts are trying to revive an idea nearly seven decades old: the creation of an international park.
Getting the US and Mexico equally invested in Big Bend, the thinking goes, will make for more effective, more holistic preservation of the salmon sandstone cliffs, the wide brown plateaus, and the pink-snouted peccaries that look like pigs with long gray hair.
"Ecosystems do not stop at a border," says Sharon Cleary, head of international programs at the National Park Service in Washington. "You may be trying to protect half of it, while losing the other half."
And degradation of one half of an ecosystem eventually leads to degradation of the other half - as is the case in Big Bend.
But observers say Mexico should not be held solely responsible for the West Texas park's environmental problems. Many days, the pollution that obscures the magnificent gray-green vistas and the rolling, cratered plains comes from as far away as El Paso, Houston, even the Ohio River Valley. And water from the Rio Grande is being siphoned off in large quantities on the US side of the border as well.
"In the past, it was so easy to blame it on Mexico. But studies show that 66 percent of the air pollution is coming from the US," says Jim Nations, vice president of the National Parks Conservation Association's State of the Parks program. His organization just released a report detailing the extent of the problems in Big Bend and calling for the establishment of an international park in the area.
Currently, there are 169 binational protected areas in 113 countries. This would be the second in the US, after the 1932 establishment of Waterton-Glacier International Park along the Canadian border. The idea for a similar park along the Mexican border here in the Big Bend area was first proposed in 1935, but negotiations were interrupted by the start of World War II.
When President Franklin Roosevelt finally established Big Bend National Park in 1944, he said: "I do not believe that this undertaking in the Big Bend will be complete until the entire park area in this region on both sides of the Rio Grande forms one great international park."
For its part, Mexico has taken significant steps in recent years to preserve the land across from Big Bend. In 1994, then-President Carlos Salinas designated 500,000 acres of the Maderas del Carmen area as a national preserve, but the Mexican government never purchased any land and it remained in private hands.
Two years ago, a Mexican cement company bought 136,000 acres to be set aside for a wildlife refuge, and today, the idea of an international park has the backing of Mexico's new parks director.
But experts agree that reviving the idea comes at a particularly bad time for the US. Since the terrorist attacks of Sept. 11, border security has been a top priority - even in parks that bump up against national boundaries.
At Big Bend, for example, informal border crossings have been shut down, and visitors are no longer allowed to cross into the United States though the park at Waterton-Glacier. Congress provided border parks with an extra $2.5 million in security funds last year.
"Since 9/11, the international border has become less porous rather than more porous," says Craig Allin, a political science professor at Cornell College in Mount Vernon, Iowa. "So I'm surprised to hear anyone talking about this idea in a progressive way."
Dr. Allin, a specialist in wilderness preservation and management, thinks the idea of an international park is good in theory. But in practice, he says, "interagency cooperation is not all it's cracked up to be."
That doesn't mean the need for cooperation is not there - especially along the US/Mexico border, he says. "Often, there is less development along the Canadian border. By contrast, parks across from Mexico frequently have enormous population press and poverty. So the park service is trying to maintain the quality of the ecosystem under situations that make that impossible to do."
But officials at Big Bend say there have been some success stories in recent years. Black bears, for instance, were extirpated through hunting and loss of habitat by the early 1950s and placed on the Texas endangered species list in 1987. Today, there are between 25 and 30 bears in Big Bend - and they've come, ironically, because low water levels in the Rio Grande meant they could cross into the park from Mexico.
Desert bighorn sheep and peregrine falcons, whose populations were also eradicated from the park, are also beginning to make a comeback.
"These are things that we are really proud of," says Big Bend National Park Superintendent John King. While he strongly supports the idea of an international park, he also believes that most of the 300,000 visitors that come to Big Bend each year still enjoy themselves - even if they're aware of the environmental problems threatening the area.
Keith Gardner is one of them. He and his wife, Bobbie, had heard of Big Bend all their lives and are finally spending a week here. They've been on a Jeep tour, a canoe tour, and hikes across the park's 800,000-plus acres.
"We are loving it," says Mr. Gardner, sweating and smiling after a canoe trip through the Santa Elena Canyon. "But when we were driving into the park that first morning, we saw all this smog. It felt like we were back in Dallas."