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 centerpiece of
the State Water
Project (SWP) and its largest water storage facility.
Located about 70 miles north of Sacramento at the confluence of
the three forks of the Feather River, Oroville Dam is an
earthfill dam (consisting of an impervious core surrounded by
sands, gravels and rockfill materials) that creates 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.