A federal appeals court has sided with environmental groups in a long-running dispute over domestic sheep grazing in Colorado’s Rio Grande National Forest, ruling that the U.S. Forest Service (USFS) acted arbitrarily and capriciously when it approved grazing permits that could threaten the health of native bighorn sheep.
In a decision by the 10th Circuit Court of Appeals, judges reversed a lower court’s dismissal of a lawsuit filed by WildEarth Guardians and Western Watersheds Project, who challenged the agency’s 2017 approval of the Wishbone Allotments. The environmental groups argued the agency ignored its scientific model, which predicted a high risk of disease transmission from domestic sheep to bighorn sheep and instead relied on unsubstantiated local factors to justify the grazing plan.
The court agreed, concluding that the agency’s reasoning lacked adequate support and violated the Administrative Procedure Act (APA). The case returns to the district court to determine how the agency must remedy the error.
Background
According to court documents, Rocky Mountain bighorn sheep remain a federally designated “sensitive species on National Forest System lands” due to long-term viability concerns. While habitat loss from other activities has contributed to their decline, the most significant threat is respiratory disease, specifically from pathogens like Mycoplasma ovipneumoniae, which domestic sheep can carry without symptoms.
To prevent such contact, USFS uses a tool called the risk of contact model (RCM), which estimates the likelihood that domestic sheep will encounter bighorn sheep within core herd home ranges. In earlier decisions, the agency had relied on this model to close grazing allotments deemed too risky.
USFS began in 2011 analyzing the risk of disease transmission from domestic sheep to Rocky Mountain bighorn sheep in Colorado’s Rio Grande National Forest. Court documents show that based on the RCM, USFS found the Fisher-Ivy/Goose Lake and Snow Mesa allotments posed a high risk of contact and potentially fatal disease transmission. The agency vacated those allotments, concluding that management strategies alone were insufficient to prevent interspecies contact, especially where pastures overlapped bighorn habitat.
However, when evaluating the proposed Wishbone Allotments in 2017, which overlapped with previously closed areas, USFS downgraded the RCM’s high-risk finding to moderate based on untested “local factors” like terrain and monitoring improvements. Despite objections from conservation groups citing a lack of scientific support, USFS approved the new allotments in 2018, asserting that combined mitigation strategies could sufficiently reduce risk.
In January 2019, the environmental groups filed suit in the U.S. District Court for the District of Colorado, challenging USFS’ authorization of the Wishbone Allotments. The court allowed intervention by the permittees Wayne and Jerry Brown, the Colorado Woolgrowers Association, J. Paul Brown and the Colorado Farm Bureau Federation. In March 2024, the district court denied the groups’ motion for summary judgment, prompting the appeal.
On appeal, the groups raised three claims under the APA and National Environmental Policy Act (NEPA), arguing the USFS violated NEPA by approving the Wishbone Allotments without preparing an Environmental Impact Statement and by issuing a Supplemental Information Report that avoided further NEPA review.
Final decision
In its decision, the 10th Circuit Court of Appeals concluded the USFS violated NEPA by failing to take a hard look at the environmental impacts of creating the Wishbone Allotments in the national forest. The court criticized the agency for arbitrarily downgrading the high-risk finding of its contact model, which predicted disease transmission between domestic and bighorn sheep every four years, based on untested local factors, such as topography and herding practices.
The court noted that the USFS failed to provide any scientific data to justify modifying the model’s results and instead relied on untethered logic and assumptions contradicted by evidence in the record.
“Given this data and the lack of any countervailing scientific studies,” the court wrote, “the USFS’s assertion that a combination of local factors could lower the RCM’s predicted risk rating was arbitrary and capricious.”
It further faulted the agency for overstating the effectiveness of management practices and for failing to analyze cumulative impacts to bighorn herds across the region.
The court returned the case to the district court to decide what should happen next. The appeals court said the lower court must weigh how serious the agency’s mistakes were and whether undoing the decision would cause disruption. Since the grazing hasn’t occurred since 2020, environmental groups argued that canceling the decision now would have minimal impact. — Charles Wallace, WLJ contributing editor
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