The Pecos River is the Rio Grande’s longest tributary, and it’s famously the threshold of the West. It’s also among the most endangered rivers in the United States. Dams and the impacts of agriculture and oil and gas have taken their toll, and in parts of West Texas, the river is often a muddy trickle at best.
But that’s not the whole story. Dr. Kelbi DeLaune is a Sul Ross State University professor and scientist with the Meadows Research Institute for West Texas Water. In studying the Pecos, she’s discovered the surprising resilience of this storied stream.
“I mean, it's always been harsh out here, right?” DeLaune said. “The system has never been what we would consider a big river. But for a desert river, it's stunning, and it has robust communities. The things that need to be there are there, and the ecosystem's functioning.”
The Pecos runs for nearly 1,000 miles from New Mexico’s Sangre de Cristo Mountains to the Rio Grande. As DeLaune notes, its passage through the Chihuahuan Desert has always been harsh. Laden with salt from desert soils, its waters sickened 19th century pioneers and their horses; legendary rancher Charles Goodnight called the Pecos the “graveyard of the cowman’s hopes.”
But the construction in 1936 of Red Bluff Reservoir, on the Texas-New Mexico line, transformed the Pecos here. The river below Red Bluff Dam no longer pulsed with spring snowmelt, and salinity skyrocketed. DeLaune studied this “Forgotten Reach” of the Pecos in her PhD research, and her findings were surreal.
“We have sections of the river where it's so salty that it's almost even too salty for things that live in the bays and estuaries, those transition zones,” she said. “It's full-on marine environments.”
Native aquatic creatures had essentially vanished. Practically the only fish here was an Atlantic Ocean native: the Gulf killifish. Somehow this marine creature has adapted, changing how it mates and where it lays its eggs. The fish seems to subsist on cannibalism.
But it’s not all a zombie watershed. In Culberson County, the spring-fed headwaters of Salt Creek, a Pecos tributary, sustain a population of Pecos pupfish – a deeply imperiled native. And south of Interstate 10, amidst limestone canyons, springs and tributaries like Independence Creek revive the Pecos.
The greatest impact of these tributaries, DeLaune found, was not on water quantity or quality. Rather, the tributaries change the material on the river bottom, the substrate. They introduce a diversity of rocks, cobbles and pebbles and create swift channels and backwaters.
These nooks and crannies give mayflies, dragonflies and beetles places to feed and reproduce. In turn, the invertebrates support native fish in the Lower Pecos Canyonlands.
“There’s greater diversity,” DeLaune said. “The habitat has changed. It doesn't all look the same, and it's not channelized. It's still wild.”
Restoring the Pecos would be no easy thing. Red Bluff Reservoir is so full of salt and waste that opening the dam could be catastrophic.
But at the Meadows Institute, DeLaune’s geologist colleagues are working to understand the springs that sustain the Lower Pecos. And many local landowners love the river fiercely. DeLaune said that collaborating with landowners to protect groundwater and spring flow is key to preserving the Pecos.
“If we can align those goals to where we're sharing some kind of future goal in terms of protecting the river surface flows and the species that depend on them,” she said, “then we can ensure we all have water for various needs. I think landowners are a big part of this next chapter for me, which is exciting. I feel like that's meaningful work.”
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