Draft EIS_072312.pdf - Middle Fork American River Project ...

20120723-4002 FERC PDF (Unofficial) 07/23/2012
whitewater boating flows would typically involve releases of 800 to 1,000 cfs to the
peaking reach 3 to 5 hours each day during the recreation season. Alternative 1
recreation flows are the same as those specified in Forest Service condition no. 39 and
entail releases to the peaking reach that are generally higher than PCWA’s proposed
flows. Alternative 1 provides more details regarding recreational releases than PCWA’s
proposed recreational release description. Details regarding recreational releases and our
analysis of effects on recreational resources are discussed in section 3.3.5.2, Recreation
and Land Use.
Our Analysis
PCWA’s proposed recreational flow schedule for the peaking reach focuses on
providing conditions to support Wild and Scenic River outstandingly remarkable values
including whitewater boating, the Western States Trail, and the fishery. Effects on
aquatic habitat are expected to be similar under both the proposed and Alternative 1
action alternatives because the recreational flow releases differ only slightly in magnitude
and frequency. Compared with existing conditions, the recreational releases are not
likely to substantially change the quantity or quality of aquatic habitat available for fish,
macroinvertebrates, and other aquatic biota.
Project Reservoir Management Effects on Aquatic Biota
PCWA proposes changes to the water level management of French Meadow and
Hell Hole reservoir and formalization of sediment management activities at Middle Fork
interbay and Ralston afterbay including periodic reservoir drawdowns for sediment
removal and other maintenance activities, all of which have the potential to affect aquatic
biota and associated habitat at these reservoirs. French Meadow and Hell Hole reservoir
water level management is primarily intended to enhance or maintain recreational
opportunities at those two reservoirs and is therefore discussed in detail in section 3.3.5.2,
Recreation and Land Use. Sediment Management and potential shoreline erosion
associated with reservoir water surface elevation changes are discussed in detail in
section 3.3.1.2, Geologic and Soils Resources. We focus our discussion here on aspects
that pertain to aquatic habitat in these four reservoirs.
French Meadows and Hell Hole Reservoir Management Changes
The minimum pool water surface elevations proposed by PCWA would:
• result in higher minimum summer water surface elevations in French Meadows
reservoir during wet and above normal water year types;
• result in lower winter minimum water surface elevations in French Meadows
reservoir during wet and above normal water year types (enhance capacity to
accommodate spring runoff);
• result in higher winter minimum water surface elevations in French Meadows
reservoir during critical water year types;
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