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

20120723-4002 FERC PDF (Unofficial) 07/23/2012
regulatory standards, with the exception of periodic exceedances of water quality
objectives for pH. Reclamation took 222 pH measurements in the peaking reach of the
Middle Fork American River and the North Fork American River and 7 were not within
basin plan objectives. Of these, three measurements in the peaking reach were below the
6.5 minimum criteria, ranging from 5.9 to 6.4, and two in the North Fork American River
were below the minimum criteria at 5.8 and 6.4. In addition, two values measured in the
peaking reach were above the 8.5 maximum criteria at 8.6 and 9.2. Water quality
sampling associated with the Upper American River Project in Rubicon and South
Rubicon river reaches upstream of project impoundments found some pH values outside
the basin plan criteria range, with the majority of such values being less than 6.5.
Mean daily summer water temperatures along the length of most of the reaches
range from 45 to 68 o F and are generally consistent with the basin plan beneficial uses for
coldwater freshwater habitat and habitat for reproduction and early development of fish,
with two of the river reaches (the downstream reach of the Rubicon river and the Middle
Fork American River downstream of Middle Fork interbay) exhibiting transition zones
from coldwater to warmer water habitat during the summer. These transition zones result
from natural warming of the water along the length of the river reaches and are consistent
with the beneficial uses designated for these streams in the basin plan.
In project reservoirs (French Meadow, Hell Hole, Middle Fork interbay, and
Ralston afterbay), all in-situ measurements, general water quality parameters, and fecal
coliform sampling met basin plan water quality objectives or were within typical
concentrations for narrative water quality objectives with the exception of dissolved
oxygen (DO) in French Meadows and Hell Hole reservoirs. During the 2005 through
2008 sampling period, DO profiles in French Meadows and Hell Hole reservoirs showed
levels typically greater than the 7 mg/L water quality objective in the upper portion of the
water column, with lower levels that do not meet basin plan objectives in the
hypolimnion nearer the reservoir bottom. Figures 3.3.2-3 and 3.3.2-4 show the
temperature and DO sampled near the dams in French Meadows and Hell Hole
reservoirs. DO within Ralston afterbay near the dam exceeds the 7 mg/L minimum water
quality objective from top to bottom (figure 3.3.2-5).
Water quality in the bypassed and peaking reaches associated with the project met
the basin plan objectives, or was within the expected ranges for narrative water quality
criteria, with a few exceptions. Exceptions in the bypassed reaches are as follows:
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