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In the final 100 miles of the Pecos River, as it journeys south through far West Texas to empty into the Rio Grande, there is one public access point.
A Val Verde County road crosses the river near Pandale, an abandoned pioneer settlement 55 miles from the closest population center. The next direct link to urban civilization on the river comes only after 50 more miles, at the U.S. Highway 90 bridge. In between, signs of modern human life are limited to the rare ranch house on a distant river bluff.
Its rocky rapids — navigable only by canoe or kayak — and its long stretches of windy lakes keep all but the most dogged paddlers from its waters.
“You are confronted with all this harsh desert beauty. It’s a very, very tough trip,” said Greg Williams, who has traveled to the Pecos region for 25 years through his work with the San Antonio-based Rock Art Foundation, which supports the preservation of archaeological remains on the river. “It’s remarkable, and it will change you. But it’s tough. It’s a very humbling experience.”
Isolation has allowed the Pecos to avoid some of the challenges that increased development has brought to many of the state’s other waterways. But it has not been spared from a less direct threat — the gradual ecological changes wrought by the manmade lakes bookending its passage through the state.
Starting in the mountains of northern New Mexico, the river enters and leaves Texas through two reservoirs. Before joining the Rio Grande to fill Lake Amistad, it runs about 350 miles through Texas after hitting the Red Bluff Reservoir on the state’s border with New Mexico.
About 100 miles west of Midland, the Red Bluff captures much of the water that flows from the river’s source in New Mexico, leaving the upper reaches of the river heavily dependent on rainfall for replenishment.
The stored water that does flow downstream is salty after picking up the minerals left behind in the reservoir, contributing further to the river’s naturally occurring high salinity. Salt levels are also magnified by surface water withdrawals for agricultural purposes — the river is the sole source of irrigation for acres of arid farmland in the region. Drought makes all of it worse.
The high-salt conditions are perfect for a species of coastal algae toxic to freshwater fish, said Tim Birdsong, the ecosystem and habitat chief of Texas Parks and Wildlife’s Inland Fisheries division. After first invading the upper Pecos in the mid-1980s, he said, the algae have spread to other rivers in the state, including the Trinity and the Brazos, triggering widespread fish kills. The algae blooms on the Pecos have imperiled its diverse aquatic life, including a kind of minnow known as the Pecos pupfish, whose primary habitat is certain parts of the river and its tributaries.
In the last decade, the state has invested about $4 million in an attempt to understand how to control the algae outbreaks, Birdsong said. Several universities have also picked up on that research, but it has not resulted in a successful method of curbing the algae’s growth in Texas waterways.
“We have done just about all we can to get at this issue and we aren’t seeing any real cost-effective strategies at managing algae blooms in streams and rivers,” he said.
As the river flows south, it is increasingly fed by groundwater springs, creating a healthier ecosystem, Birdsong said. The land it travels changes to deep limestone canyons, in some areas soaring 150 to 200 feet, making the water difficult to withdraw for agricultural purposes.
“As far as access, it’s almost nonexistent,” said Missy Harrington, whose family has ranched in the area since the late 1800s. “We always laughed that my great-grandfather bought the land sight unseen because they told him there were rivers on three sides, but they didn’t tell him there were 200-foot bluffs.”
The early ranching operation raised cattle, she said, but her family discovered, as many in the area did, that cattle needed costly supplemental feed to stay alive on the sparse countryside that surrounded the river. Now, the only livestock they keep are sheep and goats, which are hardier and require less water.
“I don’t think it’s changed much in the last hundred years, and I doubt that it’ll change much in the next hundred years,” Harrington said. “Maybe whenever places sell, and land gets chopped up — it’s a beautiful place to build a house, I guarantee it. But it’s kind of remote so you’re going to have to want to live in the country.”
Harrington’s land is on what is known as the Lower Pecos, which runs through the canyons that begin along about 60 miles north of Lake Amistad. The freshwater springs that feed the lower portion of the river, which is home to some of the continent’s oldest rock art, make it less susceptible to low flow and water quality issues that plague its upper reaches. But the reservoir at its mouth has also left its mark.
“What you see the Pecos now looking like as you cross Highway 90 is not what the Pecos River looked like at all. Really at that point it’s the reservoir,” said Carolyn Boyd, a Texas State University archeologist. “Underneath that bridge there’s 80 feet of silt underneath the little water that’s actually there.”
The paintings and rock carvings created by the nomadic hunters and gatherers who occupied the region 12,000 to 4,500 years ago are unusual both for their narrative composition and superior preservation, said Boyd, who directs the Shumla School, an organization dedicated to studying the region’s rock art.
“Essentially what we are looking at are the oldest known books in North America that line the river,” Boyd said.
The paintings are in dry rock shelters protected from water damage and were produced by combining animal fat with colors produced by chalk-like river rocks, a method Boyd said improved their longevity.
The construction of Amistad in 1969 brought a new element to the climate that had kept the paintings preserved for so long. Surface evaporation from the lake has added more moisture to the arid desert air, Boyd said, which has led to increased mineral accretions and microbial growth on the cave walls that hold the art, accelerating its deterioration.
The effects of the reservoir on the river, said Williams of the Rock Art Foundation, are only just now being seen.
“There are deposits on the walls, there’s insect populations that weren’t there before,” he said. “The humidity has increased, and the full extent of that I don’t think we know.”
This story is part of the Texas Tribune's "Troubled Waters" series, examining the state of Texas' rivers. Find the rest of the stories and a map of the rivers in the series here.