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

20120723-4002 FERC PDF (Unofficial) 07/23/2012
Middle Fork Development
The landscape in the vicinity of Middle Fork interbay is moderately steep,
entrenched, and confined by narrow V-shaped valleys. The vegetation is comprised of
communities dominated by mixed conifer and with some hardwood vegetation on the
surrounding hillsides; riparian species occur along the stream channel.
Middle Fork interbay dam and Powerhouse Road are in an area that is managed
predominantly for the Modification VQO. The passive microwave reflector station above
Middle Fork interbay is in an area managed for the Partial Retention VQO. Project
facilities between the river and the Middle Fork powerhouse penstock and butterfly valve
house are in an area managed for the Partial Retention VQO. Project facilities at and
above the valve house are to be managed to meet the Modification VQO.
Ralston Development
The landscape in the Ralston area is characterized by moderate to steep slopes
with elevations ranging from 1,600 to 4,000 feet. Steeply sloping hillsides are
characterized by mixed brush hardwood stands and scattered conifers.
Project facilities within this area are managed for the Partial Retention VQO since
they are within the foreground view of the Ralston Picnic Area and Ralston afterbay. To
the south of the Middle Fork American River, which includes the confluence with the
Rubicon River, project facilities are within an area which is to receive interim protection
of its Wild, Scenic, or Recreational values until Congress makes a formal designation by
law or disposes of the proposal. Lands within this area are to be managed to meet the
Retention VQO.
Reservoir Levels
Typical reservoir annual operation results in the capture or diversion of water into
Hell Hole and French Meadows reservoirs during the winter and spring (filling period),
and drawdown of the reservoirs during the summer, fall, and early winter (release
period). Project operation varies from year-to-year based on the timing and magnitude of
spring runoff, which is influenced by the amount of the winter snow pack and ambient
temperature conditions, as well as precipitation (see figures 3.3.2-1 and 3.3.2-2). Despite
the year-to-year variation, both reservoirs typically reach their maximum storage for the
year in late spring or early summer. Reservoir levels begin to decline in the summer and
continue to decline until the late fall or winter. Reservoir levels are typically at their
lowest in January. French Meadows reservoir maximum and minimum operating water
surface elevations are 5,262 feet and 5,125 feet, respectively. Hell Hole reservoir
maximum and minimum operating water surface elevations are 4,630 feet and 4,340 feet,
respectively. Although more shoreline is exposed as water surface elevations at Hell
Hole and French Meadows reservoirs recede, this effect is diminished from farther
distances where other factors such as lighting, cloud cover, air quality, and vegetation
growth influence the view.
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