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 39 minutes | -1085 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
Note:
The following is transcription of comments provided by Bryan Foster on 2014-05-26, after his participation in the flow study.
Four different levels were used for the flow study. All levels referenced below are 'in channel' levels. To translate listings below to their appropriate USGS gauge readings, you would have to add 2820 cfs. (We are now using a 'virtual gauge' which uses that calculation.)
I: Dam to Pool
The first difficulty is getting safely into the river. As flows increase, the current in the put-in eddy near the dam gains strength, making it difficult to get into your boat and then to charge out into the current. The first two rapids can be scouted by walking along the trail on the East side of the river (a section of the Ice Age trail). Just below the first rapid there is a rock outcropping you can walk out onto scout both drops. This may be used as an alternate (though less than ideal) put in.
The first rapids has 2 main lines. The left line is to the right of a large rock. There are a few waves and one rock that pops up just before a large rock at levels below 1800cfs in the channel. The right line is harder to get to, as you need to ferry across a lot of water to get there. You then run the current about 15 feet off the right bank.
The second rapid in this first sequence forms a catch-on-the-fly wave at levels above 1500cfs which increases in strength to 4000cfs, but is still playable. The river splits, with most of the flow going straight into a boulder garden, and a lesser amount heading off to the right. This first section ends in a large pool before the next section begins.
II: Pool to Ledge
After the pool the pace picks up once again. This is generally a read-and-run section, since the path for scouting is far from the river through this stretch. There are a few eddies to hop down the right bank and a few play opportunities at the entrance and by the eddies, but be on the look-out for a few pour overs in this stretch.
The rapid takes a gentle left hand bend then straightens out and the gradient eases as you approach the Main Ledge drop. Scouting from the left is done for various sneak routes and for punching the meaty hole at certain levels. You can also scout from the right bank for a double drop.
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.)
III: Below Ledge to Powerhouse
Just after the ledge some large wave holes form at 1800+ cfs. There is large rock pour-over just off the left bank, and just to the right of it is where the wave-hole forms. The pour over offers eddy access to this rodeo hole. The gradient eases and most of the water makes its way over to the right bank, as do most boaters. The gradient builds through some waves that offer play spots and a number of eddies down the right shore. One small ledge/pour-over forms in the middle, but is easily missed by following the wave trains down the right side. A short slack-water breaks up the top of Mark Falls from the middle of Mark Falls. The bottom section contains fewer waves and eddies but more holes and pour-overs, so keep you guard up! The holes did not washout from 1500 cfs all the way to 4000 cfs -- things just got bigger. There is one more slackwater before a runout section with most boaters getting back to the left side of the river. This portion ends with boaters ferrying across the outwash from the Powerhouse to the takeout on river-left.
Take Out
Trip Reports
Log in to add a reportGrandfather Falls Release 5/17/2025 - Chris Evans
May 28, 2025
Release 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.
Bryan Foster
Jun 12, 2017
Here is a video of the main drop at 3600 cfs per merril USGS gauge.
https://youtu.be/1jgnOFwzIiQ
Bryan Foster
May 24, 2014
There were many line available for this ledge drop at the levels of 1500,1800,2000,4000 cfs in the channel.
Thomas O'Keefe
May 24, 2014
Helge Klockow and Bryan Foster begin their run at the base of Grandfather Falls Dam.
