State begins an aerial assault on a water-sucking weedSOCORRO, NEW MEXICO — Late-summer air traffic over Socorro County in central New Mexico is generally pretty sparse — usually only a few light planes or high-flying Stealth bombers from nearby military bases. But it jumped in September, when herbicide-loaded helicopters began to spray poison across sprawling stands of saltcedar on the Rio Grande. Spurred by hopes that killing the exotic plant on a major scale would “salvage” significant amounts of scarce water, the New Mexico Legislature has allocated more than $6 million for saltcedar control projects over the last two years.
Reviled across the West as a “scourge,” saltcedar — or tamarisk — has spread wildly over an estimated 1.2 million acres in 11 states (HCN, 5/25/98: Tackling Tamarisk). Some say it sucks up the equivalent of the water supply of nearly 5 million people each year. New Mexico environmentalists joined forces with the state soil and water conservation districts to lobby for money to target a common plant enemy.
“We thought it would be a lever for ecological restoration,” says Steve Harris of the group Rio Grande Restoration. “Not just bombing the saltcedars back to the Stone Age.”
But with a June 2004 spend-it-or-lose-it deadline looming, the soil and water districts in control of the money opted for a quick-kill weapon — an herbicide called Arsenal. They’ve sprayed thousands of acres along the Rio Grande and its tributaries.
However, tamarisk might not be the only casualty. Biologists fear that the aerial spraying could kill native cottonwood trees, while farmers and ranchers are worried about their crops. And the lack of a restoration plan for the river could spell disaster in the future.
“Anything you do like that will have consequences, because if you kill off a lot of saltcedar, it will affect other organisms,” says retired University of New Mexico biology professor Cliff Crawford, who has studied the Rio Grande ecosystem for years.
How effective is it?Landowners voluntarily sign up for the aerial spraying and public notices are issued. Pinpoint satellite guidance technologies assure accuracy, even avoiding buffer zones around endangered southwestern willow flycatcher nests, say soil and water conservation district officials.
Jim Tompkins, product manager with the U.S. Environmental Protection Agency, says Arsenal “does not pose an unacceptable risk” to humans. Because the chemical isn’t supposed to be used on or near waterways, the agency had to issue an exemption for spraying. But according to Tompkins, the agency may soon lift that prohibition entirely, because of the ruling that the herbicide poses no “unacceptable risk.”
Not everyone agrees spraying is harmless. Farmer Leo Mendoza, who lives in Socorro County, turned down aerial spraying because he remembers what happened in his neighborhood 50 years ago. Back then, Mendoza says, a spray project “killed everything except the saltcedar.”
Farmers, lost crops, and the land didn’t recover for several years, he says. Near Albuquerque, the Middle Rio Grande Conservancy District has decided to forgo aerial spraying because of fears it would kill the cottonwoods, says district biologist Sterling Grogan. Instead, managers control saltcedar by sawing down the trees and quickly injecting them with hand-delivered herbicide.
Other control methods, such as ripping trees from the ground or grinding them up, are being tested in areas where saltcedar is interspersed with other growth, and the Legislature has allocated $100,000 to see if goats can be used to eat the trees. But New Mexico goat farmer John Noel says the goat experiment pales in comparison to spraying by the “herbicide lobby.”
The prime benefactors, it turns out, may not be the rivers but the chemical companies. On the Rio Grande spraying alone, the districts spent $1.4 million — mostly for Arsenal, which costs $250 a gallon.
Afterlife of a cedar standAnd the environmental benefits of the program may have been oversold. Saltcedar control advocates often point out that a single tamarisk can “drink” about 200 gallons of water per day. “That’s a number pushed by a lot of people,” says UNM biology researcher James Cleverly. “It’s not possible for any plant to use that much water per day.” Actual water increases gained by eliminating saltcedar can vary widely, and they don’t always show up in actual stream flows.
Touting big gains helps justify projects like the aerial spraying, Cleverly says, because “the more water they say they are saving, the more contracts they get.”
Environmentalists say the overriding question, however, is what will happen after the saltcedar is removed.
“Everybody seems to be in a hurry-up mode,” says Kevin Bixby of the Las Cruces-based Southwest Environmental Center. Conservation district revegetation plans are incomplete and “unrealistic,” he says, in some cases simply calling for burning or bulldozing dead saltcedar stands.
Despite the thousands of acres it involves, the aerial attack is in fact only a start. In the Pecos drainage, officials figure only 25 percent of the infested lands have been tackled, and even less than that along the Rio Grande. But more money may be on the way: Sen. Pete Domenici, R-N.M., is pushing for a $50 million river restoration bill, which could bring $10 million a year to the state for the next five years — much of it for saltcedar control.
The author writes from Socorro, New Mexico.
Rio Grande Restoration 505-266-3609
Southwest Environmental Center 505-522-5552
New Mexico Department of Agriculture Agricultural Programs and Resources, 505-646-2642
New Mexico Association of Conservation Districts 505-981-2400