Carter Reservoir Mustangs, Inc. v. United States Department of Interior

Case Overview

Carter Reservoir Mustangs is a challenge to the Interior Department's plan to round up hundreds of wild horses across three herd management areas in northeastern California. In late 2025, the Bureau of Land Management adopted its 2025 Gather Plan authorizing the removal of 470 horses from the Carter Reservoir area, 273 from Buckhorn, and 113 from Coppersmith, with the roundups scheduled for September 2026. Two nonprofits, Carter Reservoir Mustangs, Inc. and Wild Horse Education, along with individual advocates, sued in the Eastern District of California, arguing BLM's overpopulation finding rested on outdated "appropriate management levels" set decades ago and never re-evaluated, in violation of the Wild Free-Roaming Horses and Burros Act, the Federal Land Policy and Management Act, the National Environmental Policy Act, and the Administrative Procedure Act.

Judge William Shubb granted a preliminary injunction blocking the roundups. The court found BLM likely acted arbitrarily and capriciously because it relied on an assumed population growth rate while its own environmental assessment showed the herds' actual growth had been far lower, and in many years negative. The gathers are halted while the case proceeds.