Lethal Rotenone Plan Aims to Trade Wilderness Rainbows for Cutthroat

Montana’s picturesque Absaroka-Beartooth Wilderness, just north of Yellowstone National Park, holds reams of recreational opportunities including hiking, backcountry skiing and fishing. The latter is due to the human introduction of rainbow trout beginning in the 1930s across the wilderness area, including in Hidden Lake, which flows into Buffalo Creek.

Montana’s Custer Gallatin National Forest released its final decision in August to go forward with plans to administer a chemical piscicide on a 46-mile stretch of Buffalo Creek to kill off nonnative rainbows and replace them with another nonnative species: the Yellowstone cutthroat trout.

The plan, a joint effort between the Forest Service; Montana Fish, Wildlife and Parks; and Yellowstone National Park, seeks to protect native Yellowstone cutthroat trout downstream in the Lamar Valley, according to the release. It authorizes up to 81 helicopter landings and 60 days of motorized tool use to administer the EPA-approved chemical piscicide known as rotenone.

Missoula-based environmental group Wilderness Watch filed a federal lawsuit against the Forest Service on Nov. 8, saying the plan will “poison miles of stream and wetlands” and challenging the agency’s “unlawful decision.”

“At its core, it's an attempt to make this place be what [land management agencies] want it to be, rather than what nature wants it to be,” George Nickas, executive director of Wilderness Watch, told Mountain Journal. “And that really is the antithesis of wilderness.”

When Nickas says “wilderness,” he’s referring to the Wilderness Act of 1964, which established the framework for conserving federal land as national wilderness areas. The lawsuit argues that the Buffalo Creek plan violates this piece of legislation on multiple fronts.

Hidden Lake and upper Buffalo Creek are naturally fishless. The lawsuit argues that replacing one nonnative species with another is fundamentally disruptive. Additionally, the use of helicopters and motorized equipment are prohibited by law barring their necessity for preserving the natural state of the wilderness. As far as being necessary, Nickas said, “this plan obviously isn’t.”

Rotenone would kill any gill-breathing aquatic life in the creek, alongside the targeted rainbow trout, which Nickas believes would have a cascading impact all the way up the food chain.

The plan is an attempt to expand cutthroat trout beyond their native range to protect the population across Greater Yellowstone, the release said. The fish occupy just 43 percent of their native range, according to a 2017 National Park Service report, and are challenged threefold by nonnative trout species through predation, competition and hybridization. The Forest Service identified Buffalo Creek as the Lamar River drainage’s primary source of rainbow trout hybridization.

Wilderness Watch is awaiting a response and subsequent court date issued by the federal government. Nickas said cases like this typically wrap up within a year, providing enough time for the case to work itself out before implementation would begin next year.

“These projects represent a mindset and an approach to managing wilderness that is anathema to wilderness,” Nickas said. “If these kinds of projects go forward … then really nothing less than wilderness itself is at stake.”