FERC Project No. 2079 - PCWA Middle Fork American River Project ...

Application for New License Middle Fork American River Project (FERC Project No. 2079)
discussion of the potential impacts of routine maintenance, non-routine Project
recreation facility activities, modification of existing facilities, or construction of new
facilities on aquatic habitats in the MFP. Section 6.2.4 provides a species-specific
summary of impacts of the Proposed Action on hardhead, FYLF, CRLF, and WPT.
6.2.1 Routine Operations
This section, which provides an analysis of the changes in routine operations on aquatic
habitats and species, is based on Exhibit E – Section 8.5, Fish and Aquatic Resources
Environmental Effects. Some Exhibit E tables, figures, and appendices from
Section 8.5, Fish and Aquatic Resources Environmental Effects or other Exhibit E
sections are incorporated by reference into this section. The analysis of potential
effects on aquatic resources from changes in Project operations under the Proposed
Action required detailed modeling. Refer to the introduction to this section (Section 6.0)
for a complete description of modeling conducted for this analysis. The following
describes (1) riverine physical environment, (2) riverine aquatic community and
(3) medium reservoir aquatic habitat.
6.2.1.1 Riverine Physical Environment
The Proposed Action will modify MIFs, environmental pulse flows, spill flows, operations
of the Oxbow Powerhouse, recreation flows, and sediment management. The riverine
physical habitat that the Proposed Action could potentially impact includes
(1) hydrology, (2) channel geomorphology and sediment transport and supply,
(3) riparian vegetation, (4) water temperature and dissolved oxygen, and (5) wetted
perimeter.
Hydrology
The MFP (BA/BE Map 7) includes hydrological bypass reaches and a peaking reach.
The bypass reaches are sections of streams/rivers below diversions or reservoirs where
Project operations result in the diversion of a portion of the water from that reach. The
peaking reach is the river below Oxbow Powerhouse. In this reach, flows fluctuate
substantially to meet power demand or to support whitewater recreation.
• Bypass Reaches
o Duncan Creek, North Fork Long Canyon Creek, South Fork Long Canyon
Creek, Long Canyon Creek, Middle Fork American River below French
Meadows Reservoir, Middle Fork American River below Middle Fork Interbay,
and Rubicon River
• Peaking Reach
o Middle Fork and North Fork American rivers below Oxbow Powerhouse
In the bypass and peaking reaches, the Proposed Action specifies modifications to
hydrology, including:
February 2011 6-11