Scientifically and legislatively, lakes are indistinguishable
ponds, but lakes generally are considered to be longer and
deeper lentic, or still, waters. In the 18th and
19th centuries, scientists attempted to distinguish
the two more formally, stating that ponds were shallow enough to
allow sunlight to penetrate to the bottom, but this exists
today as an unofficial point.
Lake Havasu is a reservoir on the Colorado River that supplies
water to the Colorado River
Aqueduct and Central Arizona Project. It is located at
the California/Arizona border, approximately 150 miles southeast
of Las Vegas, Nevada and 30 miles southeast of Needles,
Lake Mead is the main reservoir formed by Hoover Dam on the border between
Southern Nevada and northwestern Arizona.
Created in the 1930s as part of Hoover Dam [see also Elwood Mead], Lake Mead provides
water storage in the Lower Basin of the Colorado River. The reservoir is
designed to hold 28,945,000 acre-feet of water and at 248
square miles its capacity is the largest in United States.
The construction of Glen Canyon Dam
in 1964 created Lake Powell. Both are located in north-central
Arizona near the Utah border. Lake Powell acts as a holding tank
for outflow from the Colorado River Upper Basin States: Colorado,
New Mexico, Utah and Wyoming.
The water stored in Lake Powell is used for recreation, power
generation and delivering water to the Lower Basin states of
California, Arizona, and Nevada.
Land retirement is a practice that takes agricultural lands out
of production due to poor drainage and soils containing high
levels of salt and selenium (a mineral found in soil).
Typically, landowners are paid to retire land. The purchaser,
often a local water district, then places a deed restriction on
the land to prevent growing crops with irrigation water (a source
of salt). Growers in some cases may continue to farm using rain
water, a method known as dry farming.
Land subsidence is the lowering of the land-surface elevation due
to changes that take place underground.
Throughout California, subsidence has damaged buildings,
aqueducts, well casings, bridges and highways. Common causes
include pumping water, oil or gas, dissolution of limestone
aquifers known as sinkholes, drainage of organic soils and
initial wetting of dry soils, according to the U.S. Geological
The Landsat satellite program is a series of Earth-observing
satellite missions jointly managed by the National Aeronautics
and Space Administration and the U.S. Geological
Survey. Launched in 1972, Landsat is the longest
continuous global record of Earth observations. Landsat
data is used to evaluate agricultural production.
Lee Ferry on the Arizona-Utah border is a key dividing point
between the Colorado River’s Upper and Lower basins.
This split is important when it comes to determining how much
water will be delivered from the Upper Basin to the Lower Basin
[for a description of the Upper and Lower basins, visit the
Colorado River page].
California would not exist as it does today were it not for the
extensive system of levees, weirs and flood bypasses that have
been built through the years, particularly in the Sacramento-San Joaquin
These levees have been in place dating back to 1850, when
California first joined the union.
The Owens Valley in eastern California helped transform distant
Los Angeles to today’s sprawling megalopolis.
Roughly 100 years ago, Los Angeles recognized the need to augment
local water supplies and decided to tap faraway sources.
In 1905, the city of Los Angeles filed for water rights on the
Owens River in the eastern Sierra Nevada, 250 miles away.
Municipal crews began work on a 233-mile aqueduct capable of
delivering four times more water than the city then required.
The Lower Colorado River Multi-Species Conservation Program aims
to balance use of Colorado River water resources with the
conservation of native species and their habitat. A key component
of the program is the restoration and enhancement of existing
riparian and marsh habitat along the lower Colorado River.