Fri April 5, 2013
Drought Tests the Rio Grande
Editor's Note: This piece originally aired in April, 2013 on KUNM.
The muddy waters of the Rio Grande are still flowing through Albuquerque. But New Mexico is in the grip of long-term drought and there’s little water left in upstream reservoirs. That means this summer will probably be like last year—when 52 miles of the Rio Grande dried up south of Albuquerque.
Laura Paskus headed out to take a look with one of the world’s leading experts on desert rivers and sent us this audio postcard.
We’re walking along the edge of the Rio Grande about 15 miles south of Albuquerque. “We probably don’t want to go walk out there then, unless you want to get up to your knees in mud.”
That’s Clifford Dahm, a biology professor at the University of New Mexico.
This stretch of the river was dry last summer and fall. During irrigation season, much of the Rio Grande is channeled into ditches, then onto fields and yards. Irrigation season has already begun for the year, but for now, there’s still water in the riverbed—and also welling up from beneath the surface.
“I suspect that if we walked right out into this area, where the water is starting to show up,” says Dahm, “we would find that it would liquefy under us.”
The river and the groundwater beneath are connected. They’re two parts of one system.
Dahm points to a “backwater” – a puddle the length of a truck. “Here’s an area that clearly the groundwater is seeping in, couple different locations, starting to produce a little bit of flow. It’s very slow as you can see.”
It’s fed by a trickle of water coming from beneath the ground. The puddle isn’t muddy like the river. Instead, the water is clear. Like a bathtub ring, green algae circles the edge of the puddle and provides food for bugs and fish. The groundwater, river water, algae, fish, birds: everything is connected. Including the trees towering above the bank.
“Most of the large cottonwoods that you see along the Rio Grande come from some major floods that occurred in 1921 and in 1941,” says Dahm. “So that when people have attempted to date these trees, they find that many of them are 70 or 90 years old.”
Those floods last century sent water churning down the river and across the floodplain. They ran probably 20,000 cubic feet per second. That couldn’t happen today. Today, a big flood might run a quarter of that or about 6,000 cubic feet per second. That’s because today the river’s water is moved downstream from one reservoir to the next. And, we’re in a drought.
“The current drought that we’ve been in is pretty remarkable,” says Dahm, “both in terms of the lack of water we’ve had for the past two years and for the temperatures that have been associated.”
These days, flows like the ones that spawned the cottonwoods are more like wishful thinking: This spring the Rio Grande through Albuquerque’s been running around 400 - 500 cubic feet per second. Dahm says this meager flow is serious. “Our water supplies have been very much stressed, and larger and larger parts of the river are now without water—and they’re without water for longer periods of time.”
People still talk about the 1950s drought. But it’s just as dry today as it was back then. Dahm says the river ecosystem is adaptive. But just how adaptive is a question that lingers.