- Yellowstone National Park (YNP) and the National Park Service (NPS) have been facing two significant lawsuits over their new Bison herd management plan.
- The State of Montana has filed a lawsuit to halt the implementation of the plan, alleging violation of the NPSOA and other federal acts.
- Conservation Groups have also failed a lawsuit claiming that the new plan is not backed by research and is nothing more than a “senseless harassment.”
Yellowstone National Park is home to America’s largest and most iconic wild bison herd, a living symbol of resilience and a magnet for tourism and scientific interest.
In 2024, the National Park Service (NPS) introduced a new Bison Management Plan, aiming to manage herd size, update disease control measures, and incorporate new scientific insights.
Yet, instead of calming the debate, this plan triggered two significant lawsuits: one filed by the State of Montana, led by Governor Greg Gianforte, and another by conservation groups—the Alliance for the Wild Rockies and Council on Fish & Wildlife.
The lawsuits reflect two opposing drives: Montana’s livestock protection concerns versus conservation groups’ push for more robust wildlife preservation.
Hi. In today’s blog, I will walk you through the legal claims on both sides, the previous management context, and what’s at stake for conservation policy, Native American partners, and West Yellowstone’s future.
So, if these are some of the things that you want to know, keep on reading till the end…
Historical Background Of Bison Herd Management
Since the late 19th century, bison populations have been decimated, with populations plummeting from tens of millions to a few hundred.
Yellowstone preserved the last wild survivors, and recovery efforts have shaped modern conservation strategies.
However, in the year 2000, the government established the Interagency Bison Management Plan (IBMP). It involved the NPS, U.S. Forest Service, APHIS, Montana’s livestock and wildlife departments, and tribal partners.
Now, its goal was pretty simple:
- Maintain a wild, free-ranging Yellowstone bison herd.
- Reduce risk of brucellosis transmission to cattle.
- Manage bison migration outside park bounds.
- Sustain Montana’s brucellosis-free livestock status.
As time went by, herd size fluctuated between approximately. 2,400 and 5,500. Throughout this period, no documented case of bison transmitting brucellosis to cattle occurred, though elk have been implicated in several transmissions.
Yellowstone’s New 2024 Bison Management Plan: Did Anything Change?
In July 2024, the National Park Service (NPS) finalized a new plan related to Bison Herd Management. This was the replacement of the 2000 version.
While reading about this revised plan, two primary things stood out to me. These were:
- The new herd target range was changed from 3,500 to 6,000 animals, raising the former upper limit substantially.
- It expanded the tolerance for herd roaming beyond the park’s northern and western boundaries, giving the bison “greater flexibility to roam beyond the tolerance zones.”
As per KBZK News, NPS stated that the decision to update the BMP was the “culmination of an Environmental Impact Statement (EIS) and National Environmental Policy Act process that began in 2022.”
About the Yellowstone Bison Herd Lawsuit
At present, there are two lawsuits going on against NPS and Yellowstone’s Bison Management Plan. These are:
- Montana’s Lawsuit.
- Conservation Groups’ Lawsuit.
As you can already understand, these suits are not like the ones filed against Olaplex. These are some of the most popular lawsuits of 2025. In this case, the tiff is between two public agencies.
Let’s take a look at these two, shall we?
Montana’s Lawsuit Against Yellowstone
On December 31, 2024, Montana Governor Greg Gianforte, joined by the Department of Livestock (DOL) and Department of Fish, Wildlife & Parks (FWP), sued the Biden administration and NPS (among other defendants) to halt implementation of the new plan.
Why? Well, according to the official announcement from the governor’s office, NPS violated the National Environmental Policy Act (NEPA) by failing to incorporate Montana’s input during the planning process meaningfully.
Here’s what Gov. Gianforte stated:
“The National Park Service has repeatedly and consistently failed to engage with the State in a meaningful and transparent manner as required by law throughout the planning process…We will always defend our state from federal overreach.”
Additionally, the lawsuit also claimed that the implementation of the new plan would violate the National Park Service Organic Act (NPSOA) (and potentially the Yellowstone Park Protection Act), which mandates cooperative conservation and state involvement.
Conservation Groups’ Lawsuit
Shortly after Montana’s lawsuit, on 17th January 2025, conservation groups, the Alliance for the Wild Rockies (AWR) and Council on Fish & Wildlife, filed their own lawsuit against the National Park Service.
As per Buckrail, these conservation groups condemned the new plan for enabling “senseless harassment and pointless slaughter” of bison.
The groups argue the plan doesn’t expand bison range or restore their natural range, instead relying on outdated assumptions leading to unnecessary kill-offs.
They allege that although studies have proved that the former brucellosis plan was working, the NPS plan completely ignored these recommendations from the 2020 brucellosis study that highlight scientific uncertainties and potentially harmful management strategies.
Additionally, Alliance For The Wild Rockies states, “Park Service also failed to analyze where and when natural Yellowstone bison migration paths might overlap with cattle grazing on Bureau of Land Management and Forest Service lands outside Yellowstone National Park.”
In their announcement, the Conservation groups mentioned that the new Bison herd management plan “fail[ed] to provide any rational reason whatsoever to continue hazing, capturing, and slaughtering the nation’s last herd of wild bison.”
What Was The Response From NPS & Tribal Supporters?
NPS and tribal authorities like the Fort Peck Assiniboine & Sioux Tribes argue the plan is science-based and balanced, providing necessary flexibility while addressing all stakeholder concerns.
Superintendent Cam Sholly states that Montana had opportunities to contribute analyses and even submit alternatives. Additionally, they state that limiting the herd to 3,000 could threaten bison conservation.
Yellowstone officials pushed back, asserting that the 2024 management plan was properly put into effect after a fresh environmental impact statement identified Yellowstone as being able to sustain the new target range of 3,500 to 6,000 bison.
This is in line with the recent 10-year average of about 5,000 bison, as per the YNP record of decision from July.
YNP officials say this revised population goal represents not only changes in the landscape and public opinion since the 2000 plan was agreed upon but also significant changes due to research that has substantially altered the manager of wildlife and livestock’s understanding of the transmission of brucellosis.
Apart from the fact that fewer cattle are grazing near the park today, the researchers have concluded that elk are the source of brucellosis infection in cattle, whereas bison have not been infected and are not carriers.
Furthermore, the tribal supporters emphasize the plan’s ecological and cultural importance, noting how bison connectivity supports tribal heritage and ecosystem function.
Your Legal Guide: Potential Outcomes Of The Yellowstone Bison Herd Lawsuit
Here’s what the potential outcome of the Yellowstone Bison Herd lawsuit looks like:
At stake is not just how many bison roam Yellowstone, but how we balance wildlife restoration, agricultural safety, and collaborative management.
Montana’s lawsuit underscores economic and livestock protections; conservation groups press for ecological integrity and humane methods; NPS and tribal partners advocate for adaptive, science-based management.
These cases could shape future national park governance, wildlife law, and Native American collaboration.
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