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.
|So. American Below Slab Creek Dam|
|dream-670||500 - 3500 cfs||IV-V||69d14h53m||612 cfs (running)|
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