The Colorado River Aqueduct, a
242-mile-long channel completed in 1941 by the Metropolitan Water
District of Southern California, carries water from the Colorado River to urban Southern
California. The aqueduct is one of three conveyance systems of
imported water to Southern California, the other two being the
California Aqueduct
and the Los Angeles
Aqueduct.
California historically has been the
largest user of the Colorado
River among the seven states of the Colorado River Basin. And
for many years the state’s use exceeded its apportioned share of
the river’s water. That began changing in the 1990s.
The Colorado River Compact of 1922
marked the first time in U.S. history that more than three states
negotiated an agreement among themselves to apportion the waters
of a stream or river.
The compact is the cornerstone of the “Law of the River” – a
complex set of interstate compacts, federal laws, court decisions
and decrees, contracts and federal actions that regulate use of
the Colorado River.
The Colorado River Delta is located
at the natural terminus of the Colorado River at the Gulf of
California, just south of the U.S.-Mexico border. The desert
ecosystem was formed by silt flushed downstream from the Colorado
and fresh and brackish water mixing at the Gulf.
The Colorado River Delta once covered 9,650 square miles but has
shrunk to less than 1 percent of its original size due to
human-made water diversions.
Historically, the Colorado River
Basin swung between flood years and more extended periods of
drought. Massive reservoirs like Lake Powell and
Lake Mead provided a
water-supply buffer for dry years and insurance against damaging
floods in wet years.
In 2005, the Interior Department
launched a program to recover 27 species in the lower Colorado River, including seven
the federal government has deemed threatened or endangered or
threatened with extinction. The species include fish, birds,
bats, mammals, insects, amphibians, reptiles, rodents and plants
The Lower Colorado River Multispecies Conservation Program has a
50-year plan to create at least 8,132 acres of new habitat
and restore habitat that has become degraded.
The Mexican Water Treaty of 1944 committed the U.S. to deliver
1.5 million acre-feet of water to Mexico on an annual basis, plus
an additional 200,000 acre-feet under surplus conditions. The
treaty is overseen by the International Boundary and Water
Commission.
Colorado River water is delivered to Mexico at Morelos Dam,
located 1.1 miles downstream from where the California-Baja
California land boundary intersects the river between the town of
Los Algodones in northwestern Mexico and Yuma County, Ariz.
Consumptive water use is what happens when water is withdrawn for
use and is not returned to the local environment. Examples of
this include water that is evaporated, transpired by plants or
incorporated in products or crops.
Contaminants exist in water supplies from both natural and
manmade sources. Even those chemicals present without human
intervention can be mobilized from introduction of certain
pollutants from both
point and nonpoint sources.
Construction began in 1937 to build the Contra Costa Canal, the
first part of the federal Central Valley
Project. The Contra Costa Canal runs from the Sacramento-San
Joaquin Delta, where it draws its water near Knightsen, to
the eastern and central parts of Contra Costa County. It is about
30 miles from San Francisco.
Conveyance is infrastructure
providing for the movement of water. Conveyances are typically
thought of as human-made structures, such as a canal or aqueduct,
but can also be natural watercourses such as a river or stream.
