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

20120723-4002 FERC PDF (Unofficial) 07/23/2012
Noxious Weeds
A total of 27 noxious weed species were detected in the study area14 during
PCWA’s noxious weed surveys. Specifically, 24 species were identified at existing
project facilities and features; 18 species at project recreation facilities; and 23 species at
dispersed recreational use areas. In general, noxious weeds were common throughout the
study area, particularly at facilities and features associated with the project’s four largest
impoundments, Ralston afterbay, Middle Fork interbay, Hell Hole reservoir, and French
Meadows reservoir. The greatest number and highest densities of noxious weed species
occur near the lower-elevation project facilities (i.e., Ralston afterbay and Middle Fork
interbay) and the number and density generally decreases in the vicinity of the higherelevation
project facilities (i.e., French Meadows and Hell Hole reservoirs). Populations
were also documented along bypassed reaches and the peaking reach where no routine
maintenance activities are conducted.
Priority noxious weeds (i.e., non-native or invasive plants) are those noxious weed
species on which Eldorado National Forest and Tahoe National Forest are focusing their
forest-wide weed management efforts. There are 21 species (1,759 acres) of priority
noxious weed species in the vicinity of the project (table 3.3.3-3). The most abundant
noxious weed species observed in the study area were:
• Woolly mullein (Verbascum thapsus)—72 populations occupying about 319
acres
• Cheatgrass (Bromus tectorum)—101 populations occupying about 280 acres
• Rattail fescue (Vulpia myuros)—77 populations occupying about 225 acres
Five noxious weed species were found that had not previously been recorded in
the vicinity of the project:
• Italian thistle (Carduus pycnocephalus)
• Malta starthistle (tocalote) (Centaurea melitensis)
• Canada thistle (Cirsium arvense)
• White sweet clover (Melilotus albus)
• Spreading hedgeparsley (Torilis arvensis)
14 The study area for noxious weeds included buffer zones ranging from 10 to 100
feet from existing or proposed project facilities and riparian zones along representative
portions of the bypassed and peaking reaches.
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