Not a grand mountain by Western standards, it's a stoop-shouldered hill that bears the University of Montana's "M'. It is covered mostly by open meadows, and, like much grazing land in western Montana, it is infested with weeds alien to North America.
Most everyone from ranchers to recreationists agrees the weeds must be eradicated. But a proposal to aerial-spray leafy spurge and spotted knapweed has incited an emotional debate.
Because the weeds have no natural predators here, they've spread quickly, forcing out native plants as they move. Leafy spurge has infested 600,000 acres in Montana and 1 million acres in North Dakota. Economists estimate the weed already costs U.S. farmers $100 million in yearly losses.
Steve Cooper, an ecologist with the Montana Natural Heritage Program, the scientific arm of Montana's Nature Conservancy, calls exotic weeds "a plague that keeps growing." Alien weeds can cause birds, small mammals and grazing animals to avoid infested areas. In some cases, the land loses its ability to hold moisture, leading to erosion into local waterways that harms fisheries. Some exotics increase fire danger.
That's why authorities at the University of Montana, which owns 480 acres of Mount Sentinel, thought the local community would rally behind its plan to attack the weeds. One part called for biological control - establishing an insectary to collect and breed insects that have been shown to attack certain weed species. The second part was the sticking point - aerial spraying of pesticides.
At a public forum last year, environmental writer Richard Manning readily threw his support behind the spraying plan. Manning became interested in noxious weeds while researching his latest book, Grassland.
"I began tracing things down and discovered how dangerous exotic plants can be," he says. "They take the primary productivity out of the land in terms of building biomass for everything from grasshoppers to elk."
About four years ago, Manning sprayed his property in Lolo, Mont. He feared a band of elk would abandon the area as leafy spurge spread uphill. Now, there is a distinct line of demarcation between the native grasses on his property and his neighbors' weed fields.
Manning believes western Montana could be knapweed-free if all landowners sprayed.
But, except for one other land manager who spoke in favor of the plan that evening, Manning found himself outnumbered. Seventy-eight citizens spoke out against spraying the mountain with Tordon. Their clear message: We don't want pesticides sprayed on Mount Sentinel - ever.
Testimony was sometimes emotional: One woman equated the spraying plan to the extermination attempts on Jews and Gypsies in Europe during World War II.
Terry Egenhoff, who has written weed management plans for the Lolo National Forest, says those feelings are common. "People active in weeds and pesticides tend to gravitate toward extremes that are almost religious in nature," he says.
Bryony Schwan, director of a nonprofit group called Women's Voices for the Earth, calls people opposing any release of chemicals into the environment "toxic environmentalists."
"People have been spraying those weeds for decades," Schwan says, "and now they are a greater problem than they used to be. Spraying pesticides obviously isn't a long-term solution."
Schwan, a native of Zimbabwe, emigrated to Montana 12 years ago. She became interested in the effects of chemicals on human life while enrolled in the university's environmental studies program.
Schwan thinks exposure to chemicals, such as those contained in pesticides, have contributed to rising cancer rates and other health problems. She points out that cancer is close to surpassing heart disease as the number one cause of death in Montana, according to state health statistics.
Chemicals in pesticides can also harm the reproductive capabilities of animals, Schwan says. "After massive spraying with pesticides, you may end up with healthy meadows of native grasses," she says, "but there may be no animals there to eat them."
Ever since Silent Spring, Rachel Carson's book exposing the disastrous effects of DDT on wildlife, some researchers have tried to find alternative ways of controlling noxious weeds - with some major successes.
Thirty years ago, the Oregon dairy industry was jeopardized by infestations of tansy ragwort, a plant toxic to livestock in its mature stage. Introduced to the state in the 19th century, the bright yellow flowering plant steadily took over entire pastures across the state.
Now the tansy ragwort is considered only a common weed, thanks to the work of two insects introduced from Europe and Asia, the cinnabar moth and flea beetle.
"If you don't address the underlying causes of the infestation, you don't address the problems," says Norma Grier of the Northwest Coalition for Alternatives to Pesticides.
Despite successes like these, some ecologists in western Montana say there is no choice but to use pesticides there to save native plants before they disappear forever.
"There's too much lag time in developing natural predators," Cooper says.
Richard Manning is well aware of the health risks involved with pesticides, but he's willing to take a personal risk to save the ecosystem.
"I'm the one walking around with the backpack sprayer," he says. "I may lose some forbs or animals because of my spraying, but I feel we must hold the line on the ecosystem. All we have is bad choices. And spraying is the best of the bad choices."
These days, the University of Montana is reconsidering its plans to spray the mountain.
Mark Matthews writes from Missoula, Mont.