American, S. Fork, California, US |
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| Usual Difficulty | IV-V (for normal flows) |
|---|---|
| Length | 7.5 Miles |
| Avg. Gradient | 89 fpm |
| Max Gradient | 120 fpm |
| Name | Range | Difficulty | Updated | Level |
|---|---|---|---|---|
| So. American Below Slab Creek Dam | ||||
| dream-074 | 500 - 3500 cfs | IV-V | 03h35m | 35 cfs (rc= -0.2 ) |
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, 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 5.5. The Rock Creek Power House could provide a potential take-out or put-in if paddlers were interested in running the last two miles of the run down to White Rock Power House. This section is also class II/III with one rapid that is potentially class III+.
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 the Slab Creek dam. Dirt roads lead to the river a short ways below the dam.
Take out: The road leading to White Rock Powerhouse is gated so boaters have to park outside and walk up from the reservoir. From Highway 50 in Placerville go north on Mosquito Road. After about 1 mile, turn left on Meadow Lane to Hollond Drive. Search carefully for the road down to the powerhouse.
Mosquito Road Bridge is an alternate take out allows boating the steepest few miles while avoiding Morthelode Falls and the easier water below.
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Jason Bates wrote at boof.cem,,,,,
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Thomas M. wrote ot Boof.com
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.
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Other Information Sources:
Upper American River Project main page.
Upper American River Project
Schematic.pdf
Chili Bar Reservoir
Planning Unit.pdf
A GUIDE TO THE BEST WHITEWATER IN THE STATE OF CALIFORNIA, HOLBEK & STANLEY, 1998
Dreamflows.com is currently estimating spill into this reach using hourly reservoir elevation data. This information is provided as part of the new settlement with SMUD. Flows can be claculated from Slab Creek Reservoir elevation. To determine the approximate flow, use the following conversion table for the reservoir elevation:
1850.6 = 535 cfs
1850.7 = 650 cfs
1850.8 = 767 cfs
1850.9 = 892 cfs
1851.0 = 1025 cfs
1851.1 = 1180 cfs
1851.2 = 1310 cfs
1851.4 = 1600 cfs
1851.7 = 2150 cfs
1851.8 = 2340 cfs
1852.1 = 3000 cfs
1852.3 = 3400 cfs
1852.4 = 3600 cfs
1852.6 = 4075 cfs
South Fork American River Basin Schematic.pdf shows gauges, diversions, dams and powerhouses in the basin.
White Rock Powerhouse receives the water diverted from the river at Slab Creek reservoir. Information and historical flow data is available at USGS 11443460. The maximum diversion capacity appears to be about 3500 cfs. So there should be spills whenever inflows to Slab Creek are greater than 3500 cfs. See flows at Kyburz to get an idea. Also whenever flows at Chili Bar are greater than 3500 cfs, the excess should be flowing in the Slab Creek section.
Rock Creek Powerhouse is a run of the river powerhouse and so does not affect the total inflow from Rock Creek. The combination of flows in the creek and from the powerhouse equal the natural flow of the creek. The powerhouse has a maximum capacity of about 100 cfs, but can only divert when the creek has high flows. Historical information for the Powerhouse is at USGS 11444280 , while data for the creek is available at USGS 11444201.
Spill flows in June of 2010 have been highly variable, up to 2800 cfs over a day and quite erratic during each day. The diurnal variation at Kyburz is about 500 cfs during this same time and must affect the Slab creek pattern, but it is not easily visible in the actual Slab Creek flow pattern. This implies that large and erratic flows are coming down Silver Creek from Union Valley Reservoir and that Camino Powerhouse is also turning on and off erratically. It seems likely that irregular spill pulses traveling down the river bed at a slower rate of speed are interecting with irregular powerhouse flows when they reach Slab Creek.
Real time flow info is not available for Silver Creek, but historical records are available for a number of related gauges in these reaches. Daily records will not show hourly fluctuations but can sometimes give indications that hourly fluctuations occurred. SMUD 15 minute records are needed to see the actual flow patterns in Silver Creek that are affecting the Slab Creek Section.
SF American near Kyburz - USGS #114395. Operated by El Dorado Irrigation District, below their diversion.
SF American below Silver Creek-USGS #11442500 was operational from 1969 to 1993.
Silver Creek -USGS #11442000, just above the SF American confluence, was operational from 1922 to 1961. This gauge shows pre-dam, natural flows.
Silver Creek below Camino - USGS #11441900, shows flows since the construction of the dams and powerhouses.
Silver Creek below Junction Dam- USGS #11441800, only operated from 1987 to 1991, and only shows minimum releases from the dam. Spillway flows bypassed this gauge.
Camino PH - USGS #11441895, Maximum flow about 1200 cfs, but actual daily average output is highly variable. Probably related to powerhouse turning on and off at different times each day, even during peak runnoff.
Jaybird PH - USGS #11441780, Maximum output about 1100 cfs, but actual daily average output is highly variable. Probably related to powerhouse turning on and off at different times each day, even during peak runnoff.
| Name | Range | Difficulty | Updated | Level | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| So. American Below Slab Creek Dam | ||||||||||||
| dream-074 | 500 - 3500 cfs | IV-V | 03h35m | 35 cfs (rc= -0.2 ) | ||||||||
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| When | River/Gauge | Subject | Level | Reporter |
|---|---|---|---|---|
| 6y264d13h33m | American, S. Fork [CA] |
Almost at the end of this run
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3500cfs | Darrick Hilbert |
| 8y105d13h33m | South Fork American [CA] |
Slab Creek Dam spilling
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600 | Dave Steindorf |
| > 10 years | American, S. Fork [CA] |
Motherlode Falls
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2800 cfs | Jerry Jascomb |
No Comments
Users can submit comments.| Mile | Rapid Name | Class | Features (Legend) |
|---|---|---|---|
| 3.6 | Mosquito Road Bridge | N/A |   |
| 4.0 | Motherlode Falls | VI | |
| 6.5 | Rock Creek & Powerhouse | N/A | |
Big hole at the bottomthe 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 FallsBelow 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 enters on river right at river mile 5.5. The Rock Creek Power House could provide a potential take-out or put-in if paddlers were interested in running the last two miles of the run down to White Rock Power House. This section is also 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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5. Slab Creek Dam to White Rock Powerhouse, American, S. Fork California, US (mobile)
