BILLINGS, Mont. (AP) — Two conservation groups are working to raise $500,000 to fund modification and construction of quarantine pens near Yellowstone National Park so more bison can be transferred to tribes and avoid slaughter, officials said.

The park’s fundraising branch — Yellowstone Forever — and the Greater Yellowstone Coalition pledged to each raise $250,000, The Billings Gazette reported Thursday.

“This is one of the park’s highest priorities,” said Yellowstone Forever CEO Lisa Diekmann, who added that her group is also more than halfway toward its goal. “I think in some ways bison are even more iconic than other Yellowstone wildlife. Hopefully, our constituents love them as well.”

Greater Yellowstone Coalition Executive Director Scott Christensen said the group is just over half its goal.

The Park Service is expected to provide another $500,000 to fund the project. Yellowstone lead bison biologist Chris Geremia said construction could begin this summer with plans to expand by next winter.

Quarantine facilities are used to hold a small selection of bison for disease testing, including testing for brucellosis, a condition that can cause abortion in cattle and other animals. However some diseased animals can be trucked to slaughter facilities to reduce the park’s bison population. The process can take up to three years before bison are declared disease free and can be moved to other herds.

The Fort Peck Tribes built a state-of-the-art quarantine facility in northeastern Montana four years ago, but the state does not currently allow Yellowstone bison to be shipped to the facility until they have passed the first two of three phases of quarantine. Legislation to allow bison quarantine before phase two was tabled in committee.

The money being raised will pay for fencing to divide an existing pen in half and build two new pens, officials said. Each pen requires double fencing so the animals don’t make nose-to-nose contact, which is one way brucellosis can spread. Water infrastructure and a corral used for testing the animals would also be built.

Yellowstone National Park is currently maxed out with 105 bison in two existing pens, the additional pens would increase the capacity to 250 animals and is projected to cut the park’s slaughter program almost in half. The new pens could boost bison transfers to Fort Peck Tribes from about 30 to 80 animals a year.

Since the program began in 2016, 154 bison have been transferred to the Fort Peck Tribes, which already have a herd of more than 300, officials said. Another 45 Yellowstone bison were transferred to 17 tribal entities across the U.S., including Alaska.

Today there are about 400,000 plains bison in North America, with nearly 20,000 of them protected in about 60 publicly owned conservation herds, park officials said.

“There’s so much positive momentum now with Native American tribes to do ecological and cultural restoration of bison,” Christensen said. “The thing I like about this is it has us all pulling in the right direction — conserving and transferring Yellowstone bison to tribes to divert them from slaughter.”