The National Park Service is looking for competent hunters to volunteer to help thin the Grand Canyon bison herd. The herd size is getting too large for the area, damaging park resources including water sources.

The bison herd has about 600 head, and the Park Service says the area should only support about 200. On top of that, the herd is moving into territory where normal hunting is banned. If the herd isn’t culled the Park Service estimates that it will grow to over 1,500 animals in the next 10 years.

As a result the Park Service is hosting a lottery for hunters. They are issuing 122 tags in the first year. Hunters must not only prove their marksmanship to qualify, they must also be physically capable of hunting in the region on foot. Selected hunters will receive a once-per-lifetime tag.

The National Park Service and its Grand Canyon staff are still working out all the plan’s details. It’s possible that some of the herd will be relocated. Still, culling is a simpler and cost-effective way to deal with overpopulation.

“I would go if I had a chance to retain a portion of the meat,” said hunter Travis McClendon to KSDK. “It definitely would be worth going, especially with a group.”

The team is modeling the hunt on multiple successful culls in Colorado, North and South Dakota and Wyoming. These Western states have had to deal with overpopulated and diseased elk herds in the past.

Organizing hunters is just one part of the task. The Park Service also needs to ensure that the volunteers picked are up to the job. While the Park Service will pack out the bison heads, hides and meat on snowmobiles and sleds — and by helicopter if necessary — the hunters won’t be allowed to use vehicles while hunting.

Currently, requirements are likely to include that hunters be capable of putting a 5-shot group on a paper plate at 200 yards. That works out to just over 4 MOA. Physically the hunters must be capable of hiking 8 miles a day carrying a 60-pound pack.

The physical requirements are realistically steeper than the shooting requirements. Most of the hunt will take place on the northern rim of the Grand Canyon, at altitudes of around 8,000 feet. Planners expect the hunt to take place while the park is closed, in October through May.

Park organizers faced a similar challenge in North Dakota in 2010. Some volunteers did not make it through a week.

“We had quite a bit of snow, so you’re not in a vehicle, you’re not on a horse,” said Theodore Roosevelt National Park spokeswoman Eileen Andes. “You’re hiking through snow to shoot elk and haul them out. It was exceedingly strenuous.”

Because the bison belong to the state of Arizona, the heads and hides of the bison will be shared between tribes and federal and state agencies. The meat will be portioned out between the hunters.

Ranchers introduced these bison to the state at the turn of the 20th century to cross-breed with cattle. The National Park Service will release more details about the volunteer program when they’re finalized.