Contrary to popular belief, “100-Year Flood” does not refer to a
flood that happens every century. Rather, the term describes the
statistical chance of a flood of a certain magnitude (or greater)
taking place once in 100 years. It is also accurate to say a
so-called “100-Year Flood” has a 1 percent chance of occurring in
a given year, and those living in a 100-year floodplain have,
each year, a 1 percent chance of being flooded.
Oroville Dam is the tallest in the
United States and impounds the largest reservoir in
California’s State Water
Project, which brings water to 27 million residents and
750,000 acres of farmland.
Completed in 1968, the 770-foot earthfill embankment impounds the
northern Sierra Nevada’s Feather River, creating a reservoir that
can hold 3.5 million acre-feet
of water.
Overdraft occurs when, over a period of years, more water is
pumped from a groundwater basin than is replaced from all sources
– such as rainfall, irrigation water, streams fed by mountain
runoff and intentional recharge. [See also Hydrologic Cycle.]
While many of its individual aquifers are not overdrafted,
California as a whole uses more groundwater than is replaced.
Owens Lake is a dry lake at the terminus of the Owens River
just west of Death Valley and on the eastern side of the Sierra Nevada. For at least
800,000 years, the lake had a continuous flow of water, until
1913 when the Los Angeles Department of Water and Power
(LADWP) completed the 233-mile Los Angeles
Aqueduct to supplement the budding metropolis’
increasing water demands.
