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

20120723-4002 FERC PDF (Unofficial) 07/23/2012
Implement Alternative 1 Instream Minimum Flows
The Alternative 1 minimum flows (as specified in Forest Service condition no.
22) and our recommended minimum flows (table 5-2) are similar to PCWA’s proposed
minimum flows, with the exception of the peaking reach minimum flows (generally
from 15 to 100 cfs higher than comparable months and water years) and minor
differences associated with rounding.
Other differences between PCWA’s proposed and our recommended minimum
flows include the following:
• Our recommended measure specifies that minimum instream flows be
released by 5 p.m. on specific dates, while PCWA proposes that minimum
instream flows be released within 5 days of the dates specified in a new
license. In both cases, exceptions would be allowed when access to the
instream flow release infrastructure is restricted by weather or hazardous
conditions.
• Our recommended measure states that hourly running average flow
measurements would never be less than the thresholds specified in a new
license, except as authorized in advance. PCWA would maintain
instantaneous flows at all times to be no less than 90 percent of the required
minimum instream flow and maintain daily average flows to be equal to or
above the minimum instream flow and that daily average flows would at all
times be no less than 90 percent of the required minimum instream flow.
Deviations that are less than 10 percent of the required minimum instream
flow would be corrected within 3 days of discovery by releasing the
equivalent volume of under-released flow into the affected stream reach.
• PCWA proposes that the instream flow releases specified in a new license
would be provided within 30 days of license issuance at the locations where
existing infrastructure and stream gages can provide and measure new
releases. For locations requiring infrastructure modifications and/or new
facilities, instream flow releases would be provided and monitored by PCWA
within 30 days after completion of the required facility modifications. Our
recommended measure specifies a similar schedule where existing
infrastructure and stream gages can provide and measure new releases, but
also specifies time frames where bypassed reach infrastructure modifications
would be complete ranging from year 3 to 5 from license issuance. Until
then, we recommend that releases from existing infrastructure would be at the
maximum capability of the existing infrastructure if the designated minimum
flow is higher than the existing infrastructure could accommodate.
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