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

20120723-4002 FERC PDF (Unofficial) 07/23/2012
PCWA and the agencies may call a meeting to discuss the results or modify the
monitoring program.
Forest Service 4(e) condition no. 28 includes the Western Pond Turtle Monitoring
Plan among the plans that still need to be finalized, but provides no information regarding
any deficiencies in the existing plan. Consequently, we consider PCWA’s proposed plan
to be essentially the same as the Alternative 1 plan, and recognize that there may be
minor adjustments to the plan following additional agency consultation.
Our Analysis
Implementing the protective measures in the proposed Sediment Management
Plan, and associated monitoring for turbidity and methylmercury would protect western
pond turtles in reaches downstream of the Middle Fork interbay and Ralston afterbay
dams and identify the need for additional protective measures. We expect that increasing
minimum instream flows, establishing more naturally shaped hydrographs, reducing flow
fluctuations, increasing the wetted perimeter, and maintaining reservoir physical
conditions as provided for in PCWA’s proposed plan and Alternative 1 would maintain
or enhance western pond turtle habitat in the bypassed and peaking reaches compared
with current operations.
Impoundment drawdowns for sediment management activities affect small and
mid-sized reservoirs, which may provide suitable habitat for western pond turtles. As
part of the Western Pond Turtle Monitoring Plan, PCWA proposes to conduct a Phase I
Distribution Assessment at each of the project impoundments. This would identify if
measures to protect turtles during scheduled drawdowns are necessary. The Sediment
Management Plan includes provisions for retaining a refuge pool for fish when Ralston
afterbay is drawn down. If turtles are present in the afterbay, the refuge pool would also
serve to protect turtles. The Sediment Management Plan also includes a provision that all
reservoirs would be checked during dewatering and any stranded species would be
transported to an appropriate location. Although this measure is primarily intended to
protect fish, if western pond turtles are present, it would also serve to protect them during
scheduled drawdowns. The frequency of drawdowns is likely to be similar in the future
at Middle Fork interbay and Ralston afterbay relative to historic operations. The need for
future drawdowns at the small diversion pools would be less because of the installation of
self-cleaning wedgewire screens that would facilitate downstream transport of sediment
that previously would accumulate in the diversion pools. Therefore, under the proposed
and Alternative 1 actions, turtles, if present, would be less likely to experience disruption
from pool drawdowns than under existing conditions.
Although potential effects of pesticides on western pond turtle are relatively
unknown, degrading water quality has the potential to affect health and survival, either
directly, through toxic effects, or indirectly by changing the abundance and distribution
of zooplankton (the key food source for hatchlings). However, western pond turtles
appear to be fairly tolerant of low water quality, although there has been little research on
177