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

20120723-4002 FERC PDF (Unofficial) 07/23/2012
consistent with the basin plan objectives. Implementation of the proposed Water
Temperature Monitoring Plan would confirm whether flows are protective of the basin
plan designated beneficial uses of cold freshwater habitat and warm freshwater habitat,
and do not adversely affect water temperatures for local aquatic- and riparian-dependent
species assemblages. In particular, temperature monitoring would provide key input to
the interpretation of monitoring results associated with trout, hardhead, and foothill
yellow-legged frog, the distribution and population vitality of which are strongly related
to water temperature.
Monitoring Benthic Macroinvertebrate Responses to Project Operations
Non-fish aquatic species are important components of riverine aquatic
communities, facilitating nutrient transfer and serving as an important food source for
many fish and other species. The proposed action may affect suitable habitat for benthic
macroinvertebrates and aquatic mollusks as a result of the proposed sediment
augmentation program, decreasing water quality by use of pesticides as part of routine
vegetation and noxious weed management, and changes to minimum instream flows and
associated water temperature, pulse flows, and spill flows. PCWA proposes to
implement a Benthic Macroinvertebrate Monitoring Plan, which includes monitoring two
sites in the peaking reach and eight sites in the bypassed reaches in years 2, 3, 7, 8, 13,
and 14 from license issuance and thereafter for two consecutive years during every 10year
period during the term of a new license.
Forest Service 4(e) condition no. 28 includes the Benthic Macroinvertebrate
Monitoring Plan among the plans that still need to be finalized. The Forest Service did
not indicate if and what issues remained to be resolved to finalize the Benthic
Macroinvertebrate Monitoring Plan. Therefore, for the purposes of our analysis, we
assume the Alternative 1 plan would essentially be the same as PCWA’s plan with the
potential for additional minor modifications to occur.
Our Analysis
Increased minimum flows in bypassed reaches would result in relatively minor
changes in the depth and velocity of aquatic habitats compared with current conditions;
however, under the action alternatives, instream flows would vary monthly and between
years to better reflect natural seasonal variations that native plant and animal
communities are adapted to. We anticipate that PCWA’s proposed changes to instream
flows would result in an increase in wetted perimeter in bypassed reaches and therefore
enhanced productivity of benthic organisms. The proposed plan would enable
documentation of this expected outcome. In addition, many species of benthic
macroinvertebrates, either on an individual species or assemblage basis, are indicative of
both good and degraded water quality. The results of the proposed monitoring plan
would provide indications of any such positive or adverse effects, which may trigger
follow-up actions to determine if potential adverse effect indications are project-related
or anomalies.
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