About this permit
Boating anywhere in Dinosaur National Monument requires a permit, and the Split Mountain daily section has its own. It covers a nine-mile day run on the Green from the Rainbow Park boat ramp to the Split Mountain boat ramp — no camping, one launch per permit, launch and take out on the printed date and at the printed locations.
The quota moves with the season: one permit a day from March 7 to May 10, two a day from May 11 to September 11, then back to one from September 12 to March 6. NPS releases permits from March 7 of one year to March 6 of the next starting at 8 a.m. MT, and a person may hold only one Dinosaur permit at a time.
There is no lottery on this section, which makes it different from the Green through Gates of Lodore and the Yampa. Cancellations are re-released "randomly within 24 hours," so watching the calendar is the realistic way in once the initial release is gone.
The route
The run is nine river miles from the Rainbow Park boat ramp to the Split Mountain boat ramp. NPS calls the section "the last section of the Green River in Dinosaur National Monument," and it is a single day: launch and take out on the date and at the locations printed on the permit, with only one launch allowed per permit day.
The canyon is proposed wilderness and managed as such, so there are no motors and no vehicles visible from the water anywhere along the trip. The rapids are what NPS calls "notorious" for a nine-mile day run — Moonshine, S.O.B. and Schoolboy sit in the middle of the section — separated by riffles and fast flat water.
Many groups camp at the launch the night before because of how far it is from anywhere. Rainbow Park Campground has four sites holding eight people each, a vault toilet and no running water. At the Split Mountain take-out there are reservable group sites, seasonal flush toilets, year-round vault toilets and a seasonally operational groover dump.
Why it matters
Dinosaur's famous permits are the multi-day Green through Gates of Lodore and the Yampa, both lotteries, both booked a year out. Split Mountain is the day version — same monument, same wilderness management, no motors, no vehicles visible anywhere along the trip — and it is the one you can still plausibly get. What makes it hard is arithmetic rather than a draw: one permit a day for most of the year, two at peak. Miss it and there is no second allocation.
The feeling
You put in at Rainbow Park with the mountain standing in front of you and no obvious way through it, and then the river takes you into it. The canyon walls fold visibly — the strata are bent, not stacked — and the water moves fast enough that nine miles goes by quicker than you want. NPS keeps the put-in deliberately undeveloped "to help the visitor transition to the wilderness environment of the canyon," and it works.
