American, S. Fork - 5. Slab Creek Dam to Rock Creek Powerhouse

American, S. Fork, California, US


5. Slab Creek Dam to Rock Creek Powerhouse (Slab Creek)

Usual Difficulty IV-V (for normal flows)
Length 6.5 Miles
Avg. Gradient 89 fpm
Max Gradient 120 fpm

Slab Creek Dam spilling

Slab Creek Dam spilling
Photo by Dave Steindorf taken 10/30/03 @ 600

Gauge Information

Name Range Difficulty Updated Level
So. American Below Slab Creek Dam
dream-670 500 - 3500 cfs IV-V 00h45m 12 cfs (too low)

River Description


The Slab Creek reach begins with several class IV+ rapids that are within sight of the put-in. The river has a very continuous nature for the next four miles. Many of the rapids are long and require good class IV skills.   Mosquito Road Bridge at river mile 3.6 provides alternate access options.  The most significant rapid on the run, class V Motherlode Falls, occurs shortly after the bridge. 

The gradient eases after this point and the run becomes class II/III in nature. There also is more vegetation, primarily Alders, in the river channel in the lower section. Rock Creek enters on river right at river mile 6.5. The Rock Creek Power House could provide a potential put-in providing access to the class II/III section when SMUD completes a future downstream take-out.

Put in:   From Highway 50 in Placerville, take the Schnell School road exit and go north to Carson Rd. till N. Canyon road.   Follow N. Canyon Road to Slab Creek Reservoir road and follow that to a junction near the Slab Creek dam.  Two gated roads head downhill.  One road leads to the right and to the dam.  The other leads to the river a short ways below the dam.  Unless we can arrange otherwise, parking will be in the turnouts along the road above the USFS gates. The area by the gates must be kept clear as a turn around. Carry boats 3/10s of a mile down to the river. This will be the site of the future improved put-in.

Take out:  In the interim of a new Slab Creek Take-Out to be constructed by SMUD, the Rock Creek Powerhouse located on the north side of the river at mile 6.5 will be the public take-out.  From Highway 193 in Placerville go east 6 miles on Rock Creek Road.  The entrance to the powerhouse will be the second road on the right after you cross over Rock Creek.  The gate will be open during scheduled recreational releases by SMUD and limited parking is available by the powerhouse.  The gate will be closed all other times but public access to the river is still allowed.  BLM has made special arrangements for parking during recreational releases and we ask all boaters to respect the resource or it can be closed to our parking use.  Please DO NOT BLOCK THE GATE.

Mosquito Road Bridge is an alternate take out allows boating the steepest few miles while avoiding Morthelode Falls and the easier water below.  Unfortunately there only 3 to 5 parking spaces at this bridge.  Make sure the bridge stays clear.  There are some parking options further away.


From a rafting perspective River Runners President, John Kosakowsky wrote this excerpt from “Slab Creek: The Run That Time Forgot”:

I logged 8 trips on Slab Creek in December and January (some friends of mine rafted it 20 times!). The flows varied between 550 and 1600 cfs. At the low end, we R2ed 10 and 12 foot rafts. You can run all of the holes at low flows and are more worried about big rocks in the way than anything else. It’s a beautiful slalom course and it isn’t very pushy which is nice. At flows around 1000 cfs, a 13’ raft is ideal as there are really powerful drops and holes that want to surf your craft. At 1600 cfs it’s fast and powerful. There are at least 3 river wide ledges that have only one weakness to drive through. The lines are blind at times with the waves crashing high into the air. It starts to feel closer to Class V, and I’m sure the swims would feel at least that serious.

Read the full article on the River Runners website –


Jason Bates wrote at boof.cem,,,,,

Got in their yesterday with a bunch of folks, GREAT time had by all at about 1000cfs (falling slightly during the run). Not sure what other runs to compare to honestly, but of the runs you listed I'd say that at that flow I think Slab is a tad bit easier than Cherry Creek and the South fork of the Salmon. While none of the rapids have moves that are more than class 4 in difficulty (except Motherlode), most rapids do require some strong "read and run" skills to spot the holes and/or find the tongue or boof to deal with them.

There are a few surprises in there to keep you on your toes, but low to medium flows tend to be fairly open and forgiving while higher flows makes for a lot of very large and grabby holes. Less water things slow down a bit more, and there are more eddies to break things up but the lines get a bit more tight and technical. At moderate flows most class 5 type boaters will likely consider this run more class 4 in nature, while most class 4 boaters will likely find the run just a bit too exciting.

Taking out at Mosquito rd bridge eliminates Motherlode falls (which is a bit of work to sneak/portage). The rapid intensity builds from the bridge to Motherlode, with the last rapid or two above Motherlode being a bit of a step up from anything above the bridge. Other take outs involve more effort, in terms of hiking up out of the canyon or paddling across Chili Bar lake.

Overall I'd say this run is an a real classic: tons of fun challenging rapids, very little wood, very little "mank" or "sketch" factor, beautiful canyon, and a nice easy shuttle. It's such a shame that this canyon doesn't have flows more often, but while it does it's quite a nice treat to get to paddle it.



Thomas M. wrote ot

I think medium flows are between 900-1300. The river starts to get more difficult above 1500 and is much more technical the lower it gets like 600-800
I would rate the run class IV+ overall at medium flows with the exception of mother lode falls V which has a sneak rout on the far left and a semi difficult portage on the right. Another option if you want your shuttle shorter and to avoid portaging mother lode is to take out on river left at Mosquito Ridge rd.


I did the run today with 1200, last year at ~3000. At optimal flows between 1000-1500 I think the best way to describe it is a notch above Chamberlain's and a notch below 49 to Bridgeport. At that level it is very clean and generally pool drop but every rapid, one right after the next, all the way from put in to (Mosquito) bridge is class IV. At 3000 it's significantly pushier but not really more dangerous (though I'd rate it higher). Lower flows would actually worry me more since it would get quite rocky in a few places.

I highly recommend the take out at the bridge. Motherlode is definitely a bigger rapid than the rest but I didn't think it was all that memorable/worthwhile. And then there's quite a bit of flat water until the long, steep hike out...

There's some video from today on my blog:  
Last edited by bryant_burkhardt; 06-07-2010 at


Other Information Sources: 
Upper American River Project main page.
Upper American River Project Schematic.pdf
Chili Bar Reservoir Planning Unit.pdf 

Video-2009-by Bryan Burkhardt


StreamTeam Status: Not Verified
Last Updated: 2018-03-03 05:12:30

Rapid Summary

Mile Rapid Name Class Features (Legend)
3.6Mosquito Road BridgeN/AAccess Photo
4.0Motherlode FallsVIPhoto
6.5Rock Creek & PowerhouseN/AAccess

Rapid Descriptions

Mosquito Road Bridge (Class N/A, Mile 3.6)

Big hole at the bottom

Big hole at the bottom
Photo by Darrick Hilbert taken 05/23/05 @ 3500cfs

 the Mosquito Road Bridge at river mile 3.6 can provide alternate access and also warns of the approach to the hardest section of the river.   Below the bridge several rapids get harder, culminating in Motherlode Falls.

Motherlode Falls (Class VI, Mile 4.0)

Motherlode Falls

Motherlode Falls
Photo of Jerry Jascomb by Dave Jeffrey taken 07/15/96 @ 2800 cfs

Below Mosquito Rd. Bridge, several rapids get progessively harder as they lead towards the biggest rapid on this run.  Motherlode Falls  is an awkward portage for many boaters.   Reportedly there is a sneak line on far river left. 

Rock Creek & Powerhouse (Class N/A, Mile 6.5)

Rock Creek enters on river right at river mile 6.5. The Rock Creek Power House could provide a potential put-in providing access to the class II/III section of Slab Creek when SMUD completes a future downstream take-out. This section is  class II/III with one rapid that is potentially class III+.


During the winter and Spring the creek and powerhouse can sometimes deliver enough water into the river to provide boatable flows.   Generally though, the additional water will be less than 100 cfs.

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