Their 275,000 acre-foot
reservoir as delineated on a map by Boyle Engineering (88 billion gallons) will cover 65 % of the acreage of Tonner Canyon
including all of the riparian area and much of the canyon slopes which are
covered by walnut woodland, oak woodland and coastal sage scrub habitat. The
canyon would need to be bulldozed since decomposing organic material is not
allowed in this kind of reservoir
A 275,000 acre-foot reservoir will require a 400 foot high dam to be built
immediately upstream of the City of Brea and within yards of the
Whittier-Elsinore Fault, a major seismic feature in southern California. If this
reservoir were built and if it ever failed, we would be picking up a large swath
of Orange County from the beaches down to Mexico.
A geologic map of Tonner Canyon shows that both sides of the canyon, including
the dam sites, are covered with deposits designated as seismically induced
landslides, further evidence of both the earthquake potential and the inherent
instability of Puente Hills slopes.
One of the factors in the determination not to build the Auburn Dam in Northern
California was the
occurrence of reservoir-induced earthquakes at Oroville following construction
of the dam there. These earthquakes were noteworthy because Oroville is situated
in a region of low seismicity. Reservoir-induced earthquakes were investigated
after that earthquake by USGS and determined to be a valid hazard associated
with building large reservoirs near strike slip faults. The Whittier-Elsinore
Fault is a highly capable strike slip fault which already poses a substantial
earthquake threat to the urbanized area on top of it.
In order to take full advantage of the on going power shortage and rate
volatility facing California, Industry's most likely power plant scheme would
involve a pumpback concept between two onsite reservoirs. Building two small
reservoirs instead of one large one would reduce the storage volume (only one
reservoir could be full for a pumpback option) to less than 15% of the storage,
substantially defeating the purpose of reservoir construction.
The reservoir will be one-third the size of Diamond Valley Lake, recently
built by MWD at a cost of more than $2 billion and which was sold to MWD
customers as the ultimate reservoir needed to assure reliable storage capacity
south of the Tehachapis. Industry's reservoir, which involves much greater
construction problems, and less economy of scale, would likely cost more than $1
billion.