BLM Wild Horse Roundup 2026: Sand Wash, Fifteenmile and the $30M Plan

What's happening in the BLM wild horse roundup 2026 season

The BLM wild horse roundup 2026 season reached two closely watched herds this month: Wyoming's Fifteenmile gather ended Sept. 18, and Colorado's Sand Wash Basin gather began around Sept. 19. Days later, the Bureau of Land Management (BLM) announced $30 million from the U.S. Department of Agriculture (USDA) to expand fertility control, a month after a New York Times investigation put BLM wild horse sales in the spotlight.

This page sticks to what's documented. Official numbers are labeled as BLM's, advocates' claims are labeled as theirs, and anything we couldn't confirm stays out.

Fifteenmile wild horse gather: the final count

The gather ran Sept. 15–18 in the Fifteenmile Herd Management Area (HMA), about 81,000 acres of Wyoming's Bighorn Basin northwest of Worland. BLM cited severe drought and a herd far above what the range can carry.

• Gathered: 356 horses (131 stallions, 157 mares, 68 foals)
• Shipped to the off-range facility in Rock Springs, Wyoming: 235
• Released back to the range: 109
• Deaths: 12, all classified by BLM as pre-existing or chronic conditions; none were listed as sudden or acute

Advocacy groups that monitor gathers post their own photos, counts and observations. Those are claims, not official findings, and BLM's gather page is the official record to check them against.

Sand Wash Basin horses: still in progress

Sand Wash Basin in northwest Colorado is one of the state's best-known herds, with a volunteer team that has darted mares with fertility vaccine for years. BLM says the herd has grown to about 505 horses, roughly 140% of the top of its target range, on drought-strained land.

• Helicopter-assisted work was expected to take about 11 days, depending on weather and safety.
• As of Sept. 22, BLM reported 138 horses gathered (62 stallions, 56 mares, 20 foals) and no deaths.
• BLM's daily reports for Sept. 21 and 22 scored all gathered horses 4 to 5 on the Henneke body condition scale, which runs from 1 (emaciated) to 9 (extremely fat).
• Of the 55 horses to be returned, 22 are slated for fertility control before release.

Why Colorado is pushing back

On Sept. 3, Gov. Jared Polis and U.S. Rep. Joe Neguse asked the Interior Department for an "immediate freeze on upcoming roundups," calling helicopter drives "inhumane and unnecessary." They asked for a broader stakeholder process and closer work with Colorado's Wild Horse Advisory Committee, which state lawmakers created in 2025 through a law that also set up a state birth-control (immunocontraception) program for wild horses.

Their letter came days after the Piceance–East Douglas gather in northwest Colorado, which BLM lists as running Aug. 1 to 31. BLM records 894 horses gathered and nine deaths. It classifies six as chronic or pre-existing conditions, such as physical deformities, blindness, a badly healed neck injury and a fractured shoulder blade, and three as acute: a mare fatally injured during trailer transport, a colt found dead in temporary holding and a mare that died unexpectedly, likely of heart failure. BLM's position is that drought is shrinking forage and water, and that removals protect both the horses and the range.

The New York Times report on BLM wild horse sales

On Aug. 20, The New York Times reported that BLM sold about 3,700 wild horses in 2025, more than double previous years, some for as little as $25. The Times said it found evidence that some of those horses later entered a slaughter pipeline to Canada.

Context that helps you read the story:

• Sales are legal; BLM says slaughter isn't. A 2004 amendment to the 1971 wild horse law directs BLM to sell animals older than 10, or offered unsuccessfully for adoption at least three times, "without limitation." BLM says federal law prohibits commercial slaughter of these animals, and buyers must certify they don't intend to sell them for slaughter.
• BLM's own data shows the jump. The agency lists 3,718 animals sold in fiscal 2025 (2,387 horses and 1,331 burros), up from 1,509 in fiscal 2024.
• BLM's response. It says it does not sell or send wild horses to slaughter, that buyers sign a bill of sale promising not to, that it has strengthened that language, and that it works with law enforcement when credible information suggests a violation.
• The gap critics point to. Coverage of the investigation noted that once a horse is sold into private hands, the government's ability to track it is limited.

The $30 million fertility control plan

On Sept. 21, at a National Wild Horse and Burro Roundtable in Washington, BLM announced a $30 million USDA investment in fertility control. BLM says the money will add field capacity, train and deploy more applicators, and expand vaccine delivery across remote herd areas.

What BLM says about how far it goes:

• BLM gave 921 fertility-control treatments in fiscal 2025: 484 PZP, 99 PZP-22 and 338 GonaCon.
• Slowing herd growth takes treating about 75% of mares every year, which BLM says isn't feasible across most western rangelands.
• BLM says gathers are "still generally required" to treat horses with fertility control, calls removals the safest way to shrink overpopulated herds, and says fertility control works best once herds are down to sustainable sizes.

Groups including Humane World for Animals, American Wild Horse Conservation and Return to Freedom took part in the roundtable. Many advocates want fertility control to replace helicopter roundups rather than follow them, and Colorado's governor has asked for a freeze on the roundups. That is the core disagreement to watch as the money is spent, and the announcement did not include a timeline or a list of which herds will benefit.

Why wild horse gathers happen

The Wild Free-Roaming Horses and Burros Act of 1971 makes BLM responsible for wild horses and burros on its public lands. For each herd, BLM sets an appropriate management level (AML): the number it says the land can support alongside wildlife, livestock and other uses. Animals above AML are to be removed.

Nationally, the gap is wide:

• On the range: 85,466 wild horses and burros as of March 1, 2026, up from 73,130 a year earlier
• National maximum AML: 25,592
• Growth rate: most herds grow 15–20% a year, enough to double in roughly four to five years

BLM uses two main capture methods. Helicopter-assisted gathers push bands toward temporary corral traps and are used for large, remote herds. Bait-and-water trapping lures horses into pens with feed or water; it is slower and suits smaller numbers.

Critics, including Colorado's governor, say helicopter drives cause panic, exhaustion and injuries. BLM says crews follow its Comprehensive Animal Welfare Program, which sets humane handling standards for gathers, holding and transport.

How PZP darting works

PZP (porcine zona pellucida) is a vaccine made from the protein layer that surrounds pig eggs. It prompts a mare's immune system to make antibodies that stop sperm from fertilizing her eggs. It is non-hormonal, mares keep cycling, and the effect fades as antibody levels drop.

How a darting program runs:

1. Know the herd. Volunteers or staff identify each mare by color, markings and band.
2. Get close. BLM says a darter needs to be within about 30–50 yards.
3. Dart. A trained applicator fires the vaccine from a dart rifle.
4. Boost. A first dose is followed by a booster, then yearly boosters; BLM says PZP is generally effective for one to two years.
5. Record. Every dart is logged so the team knows which mares are covered.

Does it work? In Nevada's Virginia Range, a large free-roaming herd, volunteer darters pushed treatment coverage above 70% within four years, and foaling in 2022 was 58% lower than in 2020, according to a 2024 peer-reviewed study.

The catch is access. BLM says darting works best when a herd is near its target size and the horses are approachable, identifiable and trackable, and that most horses in larger, remote herds can't be darted. There, horses are usually gathered, treated and released, which is why 22 Sand Wash horses will be treated before going back out.

Two other tools show up in BLM's numbers: PZP-22, a longer-acting form of PZP, and GonaCon-Equine, which targets reproductive hormones and, BLM says, can last up to five or six years with a booster.

Where the horses go after a gather

1. Off-range corrals. Horses get a vet exam, vaccinations, deworming, a Coggins test, an age estimate and a freeze mark for ID. (New to these terms? See our health basics and glossary.)
2. Adoption. Suitable horses are offered at adoption events, adoption centers and BLM's Online Corral. BLM placed 4,330 animals by adoption in fiscal 2025; our adoption guide in Related below covers fees and requirements.
3. Sale. Horses over 10, or passed over for adoption three times, become sale-eligible.
4. Long-term holding. Unadopted animals live in off-range corrals or pastures, many on Midwestern ranches. As of May 2026, 58,025 animals were in off-range care.

Holding is the program's biggest bill: $101 million, or 66% of spending, in fiscal 2024. BLM estimates that each horse adopted or bought by a responsible owner saves about $15,000 in lifetime care.

What to watch next

• Sand Wash Basin's final tally. BLM posts running totals on its gather page; the operation was planned for about 11 days, so expect final numbers around the end of September or early October.
• How the $30 million is spent: which herds, how many new applicators and how fast.
• Sales scrutiny. Watch for any changes to sale rules or bill-of-sale enforcement after the Times report.
• Horses entering adoption. Mustangs removed this fall will reach adoption events after processing.

How to follow it (or help) responsibly

• Read BLM's gather pages and advocates' posts side by side, and note which numbers are official.
• Comment when BLM opens public comment on a herd plan.
• Ask about volunteering with a fertility-control partner near you; BLM says it needs more trained applicators.
• Thinking of adopting a mustang? Start with our safety and groundwork guides, then read the adoption article in Related below.
• Curious about the horses themselves? Browse breeds and behavior.