Verlin Smith, the BLM's branch chief for renewable resources in Utah, calls the rise of cheat grass, tamarisk, Russian olive and other invasive species a public lands epidemic that is strangling rangelands and wildlife habitat, and sucking up precious water resources in the nation's most arid region.
In addition, he noted, "It changes the whole fire cycle. Normally, fire in a vegetative ecosystem occurs every so-many years. But with cheat grass and other invasive plants, that time frame shortens considerably. It perpetuates the cheat grass and almost wipes out the possibility that the native species will be able to re-emerge and reclaim the site.
"This is an effort to reclaim some of these lands from invasives. Herbicides are one of the tools we have at our disposal."
The application of herbicides in Utah, much of it from the air, will occur all over the state, Smith said, with a focus on the cheat grass problem on the grazing lands of the west desert.
But the proposal, which is in a public comment period through Jan. 9, has generated opposition. Environmentalists and others fear the unknown consequences of the aerial spraying of herbicides in a wide array of areas, including national monuments and conservation areas.
One group, the Organic Consumers Association, has launched a nationwide petition drive in a bid to halt the program, which they say includes the use of toxic pesticides, such as 2,4-D, bromacil, chlorsulfuron and others.
"My concern is we just continue to make problems worse and worse," said Jim McMahon, an ecologist and activist based near St. George. "The aerial spraying of herbicides and pesticides to kill weeds is borderline insanity. You're talking about dropping stuff on the ecosystem that will enter the food chain.
"While the intention may be good and they're saying it will be safe, the fact of the matter is we don't know what the long-term ramifications of this will be. Often we find 15 to 20 years after something like this that it was just a bad idea."
BLM officials say they have gone to great lengths to ensure the herbicide program is safe.
"This program has taken a long time to develop, and the reason it has is because the risk assessment took a long time," said Smith, the agency branch chief. "We spent a long time analyzing the true risk of using herbicides at that level. We can do it, and do it safely so long as we follow the label directions and apply the appropriate mitigation processes. This isn't something where we're going out and spraying without planning or analysis of the sites."
Smith says herbicides will not be used universally. Mechanical or biological methods also are options that the agency will employ, on a case by case basis.
"It comes down to what's most effective," he said. "If we're treating juniper invasions, for instance, herbicides are probably not the best tool. Mechanical methods may be more appropriate."
The BLM official says the agency has the backing of ranchers and the Legislature in Utah. But herbicide opponents claim there are other alternatives. Some also say the BLM is probably fighting a losing battle.
"It's too late," said McMahon. "It's a global ecology. There will always be different species invading. We're really past the point of being able to do anything about it."