Fall

The Cave Falls Run is a long run starting near Yellowstone National Park that is mostly easy cruising punctuated with large drops that are at least sometimes portaged. Users report the run is great fun for rafts above 2000 cfs, and below 2000 cfs is too boney for rafts and mostly class III with one class IV a few miles into the run, plus Sheep Falls. A good minimum flow for kayakers is 600-700 cfs.

The line on the first class IV is on the right, and scout on river right due to possibility of wood in this drop. It's a pretty good slide on the right, while river left is a 10-15 fott vertical drop. A few miles below this is sheep falls, a class IV+ or Class V+ drop depending on the channel you take. The main flow is pretty manky, however the left channel is a sloping drop most of the way with about 6-8 feet of vertical at the end. The left channel is hard to hit and if you miss it you will go into the heart of the mank. Raft portage of this drop would be difficult.

Note that the uppermost gauge [USGS 13046995 FALL RIVER AB YELLOWSTONE CANAL NR SQUIRREL ID] is the flow until a diversion dam, which is a half mile above the bridge at the end of the run. From the dam, paddlers can either portage left to paddle the remaining half mile when the river is high enough, or portage right and paddle the canal to the bridge.

See G. Amaral, Idaho: the Whitewater State (Watershed, 1992).