2023 Simplot Slurry Spill in Caribou-Targhee National Forest
In 2023, the J.R. Simplot Company (Simplot) estimated 1000-1500 cubic yards of phosphate ore slurry (powdered ore mixed with water) leaked into Caribou-Targhee National Forest (CTNF) from a pipeline connecting the Smoky Canyon Mine (near the ID/WY border) to the Don Plant in Pocatello. Idaho government agencies kept it largely quiet.
In September 2023, while moving cattle within their CTNF grazing allotments, the Rassmussen Ranch-owner's son encountered a large quantity of dark substance in a dry creek bed. The Rasmussens reported their discovery only to learn that the U.S. Forest Service (USFS) was aware of the May 2023 spill as reported by Simplot. The Rasmussens expressed frustration with not being informed because they could have diverted their cattle away from the spill area.
On May 2, 2025, the Rasmussens filed a $280M lawsuit against: Simplot; the Idaho State Department of Agriculture (ISDA—which oversees the USFS/CTNF district); the Idaho Department of Environmental Quality (IDEQ); and the U.S. Environmental Protection Agency (EPA).
The NOW-CLOSED (voluntarily dismissed) lawsuit sought damages for alleged toxic contamination of Rasmussen cattle characterized in a 212-page complaint as “nothing short of an ecological disaster.”
On 7/29/25, a legal “Notice of Voluntary Dismissal” was filed by the plaintiffs preceded by a defendant filed "Stipulation of Dismissal With Prejudice" quietly ending the entire case on 07/30/25.
With the Rasmussen case closed, no judge or jury will decide the merits of all the evidence. We are left to simply trust that public interests were protected over conflicting interests. Unfortunately, the lawsuit raises many unanswered questions.
--Why was the slurry spill kept largely quiet from public awareness? Per a public record request, the USDA/USFS created only one notice dated October 2023 and the agency is unable to confirm it was posted on their public information page on their Caribou-Targhee webpage.
--Why did the regulatory agencies rely almost entirely upon Simplot to conduct its own investigation and report their findings. Isn't independent verification the responsibility of regulatory agencies?
--Why did Idaho officials accept the initial Simplot 5-gallon leak estimate (later revised and significantly increased)? Note: Simplot slurry is transported via a closely monitored pipeline requiring extreme pressure which cannot be shut down for long periods. The smallest of leak would produce a sizeable amount of material very quickly.
--Did the USFS/CTNF investigate the pipe breach in May 2023? If not, why?
--Despite snowpack and remoteness, upon notification of the slurry spill, did the USFS/CTNF fail to verify the quantity of the spill using available inputs (i.e. diameter of pipe, PSI (1500psi), the quarter-sized hole, slurry density, etc.) and to take timely action to mitigate/slow the spread of the phosphate ore slurry, ultimately allowing material to spread approximately 2.4 miles across public forest land and into waterways?
The public is not served when information is kept from them. We deserve honest, timely reports of incidents, and answers to these questions.
