Tonegawa, Minakami, Gunma Prefecture
Class III-IV
Outfitters: Uncle Bear Rafting and Kayak (site has water levels), Great Outdoors, Top Minakami
Logistics: Mapple 53 D7. The put-in for the full run is on the downstream river right side of the Highway 63 Bridge across the XXX River. For those who want to skip the most challenging rapids of the canyon section you can put in closer to town. Area Map.

Addition Information: Feature Article on Minakami rafting

Season: April to June during snow melt. Flows are fairly consistent as it is regulated by dam release.

Scenery: The first section through the canyon is very scenic with beautiful bedrock walls and and a mixed deciduous forest. As the run opens up into the hot spring town of Minakami the run passes through an urban setting. The final third of the run cuts through a shorter gorge section that is scenic and popular with day hikers.

Description: During the spring snowmelt Tokyo area paddlers flock to this run for some of the best whitewater within a day trip from Tokyo. Minakami is better-know as a hot-spring town at the base of the mountains in the far reaches of Gunma Prefecture. Hot spring inns and ski slopes dot the mountains surrounding town (Takaragawa Onsen). When it's up the river is fast and continuous which makes rescue a challenge--many have had to search for their gear several kilometers downstream in the reservoir.

Within a couple hundred meters of the put-in on a tributary you'll be dumped onto the Tonegawa. The canyon consists of two kilometers of continuous whitewater with two distinct class IV drops. The first can be scouted from a bedrock island on river left (photo). The line takes you down the main tongue on center right through the exploding waves and powerful hydraulics. After more continuous and powerful III+ whitewater the river drops into the next class IV rapid. You can't scout this drop from above, but you want to work your way right and stay out of the Room of Doom eddy on river left. The action continues with more continuous whitewater down to the railroad bridge. The rapids in the canyon are not particularly challenging technically, but the water is big and powerful. A swim will likely continue all the way to the railroad bridge at the bottom of this section as there are very few places to perform a rescue, and even if you could get someone into an eddy their are even fewer places to empty and reenter a swamped boat.

Once you exit the canyon the river opens up slightly but the swift current and bedrock-formed rapids provide continuous class III+ action for the next 8 km. This section starts just upstream of the Minakami train station. After paddling past the train station you pass under a bridge and enter the Minakami Hotspring Hotel Canyon (photo, video 2.3 MB). A wall of hotels lines the bedrock canyon on both sides for a bit less than 1 km before opening up to swift class II/III. The next major rapid is The Devil's Staircase (Akuma no kaidan). There is a high bridge overhead and a walkway along the bedrock wall on river left that makes a great scouting trail. This III+ rapid consists of a series of bedrock ledges that form waves and holes (video 5.6 MB).

A short distance downstream the river plunges through the final two drops of the run. The first contains a large hole on river right, but a smaller hole upstream to the left requires that you enter the rapid just right of center and then quickly move across to river left. The run ends with one more straightforward class III+ rapid. Take out on river left just after passing under the bridge. Some decent whitewater continues downstream but the rapids begin to spread out and become easier with longer stretches of flatwater in between.