Wisconsin
C) Grandfather Falls (1 mile)
| Difficulty | II-III+(IV) |
| Length | 0.89 mi |
| Avg Gradient | 60 fpm |
| Gauge | Grandfather Falls Natural Channel |
| Flow Rate as of 42 minutes | -953 cfsbelow recommended |
| Reach Info Last Updated | March 15, 2025 |
River Description
Our 'virtual gauge' subtracts the penstock capacity from the USGS gauge to approximate flow in the natural channel.
Better gauging for this run is available from https://www.wisconsinpublicservice.com/environment/hydrodata#ID0EGBAA
Between Grandfather Dam and the powerhouse lies very nearly a full mile of wide river, with an amazing assortment of rocks, bedrock, and ledges. With adequate water, this wild stretch of river should allow many options of routes and plenty of play possibilities. Various sites list 89-93 feet of drop, however (best that I can tell) that is the available head-height used by the powerhouse, thus includes the height of the dam, which we have subtracted to list the available drop of this section.
There is one ledge about 2/3 of the way down which rates the '(IV)' in the description at flows around/above 2000 cfs . At low-to-moderate flows, this reach may be more in the II-III range, but the continuous nature of the rapids, and pushiness (as it heads to higher water levels) should not be taken lightly.
There is a section of the Ice Age Trail on river left which may be used for scouting, and the road parallels the river not far back from that.
The capacity of the penstock and powerplant is reportedly 2,820 cfs, which would seem to indicate flows in excess of that should put water in this reach. I have seen the river at 'fish flow' (summer trickle), and it would appear that (at least parts of) this reach could certainly be boatable with much less water than the full stretch requires for boatability.
A flow study was conducted May 24, 2014. Participants in that flow study suggest that the run might be broken up into three (very roughly equal) sections, which are detailed in the rapids descriptions below.
A very interesting
...River Features
Put In
Granddad Ledge - Center (Right) Line
There is a 'right side' route (center-river at Granddad Ledge) which opens up at mid-range flows. This was run at 1800 cfs, but most likely was also available at 2000 cfs. No scouting was done of this line at 4000 cfs. A large rock in the middle of the landing zone would be of concern for higher levels. See the picture -- the rock could piton and vertically pin a boat.
Granddad Ledge - Main (Left) Line
While not all that tall a ledge, this develops a pretty mean-looking hole at quite a variety of flows, so is definitely worth a scout (and likely a portage). Sneak lines to the left were popular choices during the flow study, with the hole only being punched at 2000 cfs in the channel (when the hole appeared to be flushing best).
Check out the following video, scouting the ledge (no boater in video) at 3600 cfs on the Merrill gauge:
(Note: This was from summer of 2017, while the penstock was being replaced, so all flow was in the river channel.)
Take Out
Trip Reports
Log in to add a reportRelease level was about 1800 according the to the friendly dam operators. The first rapid below the dam is a solid class III which can be tricky with no warm-up. Next rapid can be run either down the main center/left channel or the right channel. Most of the river was read and run class II-III with some decent eddy lines and surf waves.
We scouted the big ledge on river right the first run. The far right channel drops over two small ledges and would be an easy sneak if the current over first ledge wasn't pushing immediately into a slightly undercut boulder with wood. Nobody ran the right line. Scouting on river left immediately above the drop is much easier. Running tight left is a bit scrapy, but it avoids the big ugly hole. Then just deal with some squirrely waves/holes and punch the bottom hole. I ran this line, and the others in our group walked. Someone should run down the middle and tell me how it goes.
The last rapid before the powerhouse has a neat creeky line down the far left channel. At the bottom of this rapid on river left is a decent surf wave and ender spot with eddy access.
Overall, this stretch has a few lively rapids with OK play for a half-slice or full-slice. It was a bit scrapy in places; definitely some paddlesnakes in there to watch out for. Very pretty. Easy shuttle. Mosquitos plentiful. At 3.5 hours from the Twin Cities, it's a hike for me for such a short run, but it might be nice to try to schedule these releases on a Friday afternoon before a Wausau release.
Here is a video of the main drop at 3600 cfs per merril USGS gauge.
https://youtu.be/1jgnOFwzIiQ
Too low, very rocky.
There were many line available for this ledge drop at the levels of 1500,1800,2000,4000 cfs in the channel.
Helge Klockow and Bryan Foster begin their run at the base of Grandfather Falls Dam.
Grandfather Falls Dam, FERC P-1966.
This is the big ledge in the Grandfather Falls sequence, shot at low water (June 24, 2008).
Grandfather Falls dam releases only in early spring to release in this usually dewatered section of the Wisconsin river. What follows down from the dam is continous II-III water for nearly a mile.