Here’s what it means for those wanting to do the popular Rim-to-Rim-to-Rim run.

The National Park Service announced today that it will begin issuing Special Use Permits on an interim basis for organized, non-commercial rim-to-rim and extended day hiking and running at Grand Canyon National Park.

The Grand Canyon has become a bucket-list destination for ultrarunners, many of whom travel to Arizona to do the “Rim-to-Rim-to-Rim” run in a single day, a 42-mile journey starting at one rim, going down into the canyon, up to the top of the other rim, and returning.

The NPS estimates that up to 800 people are traveling into the canyon during peak weekend days in the spring and fall. Between 400 and 600 of them are hiking or running rim-to-rim in a single day.

RELATED: Changes Coming for Grand Canyon Runners

The permits will mostly affect organizers of groups going down into the canyon and not individuals doing the trek on their own. According to the release, the NPS identifies groups requiring permits as having one of these traits:

• Having advertised to the general public

• Required individuals to sign up prior to participation

• An organizer who has been compensated for their services

The NPS will not limit the number of permits it passes out, but will limit the size of the groups to 30 individuals. An organizer will be limited to one permit per day.

Commercial rim-to-rim day use will not be authorized.

Permits will be issued to groups with activities planned for after Sept. 15, 2014.