All-American Canal
The All-American Canal is an 80 mi (130 km) long aqueduct, located in southeastern California. It conveys water from the Colorado River into the Imperial Valley and to nine cities. It is the Imperial Valley's only water source, and replaced the Alamo Canal, which was located mostly in Mexico. The Imperial Dam, about 30 miles (48 km) northeast of Yuma, Arizona on the Colorado River, diverts water into the All-American Canal, which runs to just west of Calexico, California before its last branch heads mostly north into the Imperial Valley. Six smaller canals branching off the All American Canal move water into the Imperial Valley. These canal systems irrigates up to 630,000 acres (250,000 ha) of good crop land and has made possible a greatly increased crop yield in this originally semi-desert area. It is the largest irrigation canal in the world,[1] carrying a maximum of 26,155 cubic feet per second (740.6 m3/s). Agricultural runoff from the All American Canal drains into the Salton Sea.
The All American Canal runs parallel to the Mexico California border for several miles and with over 500 people having drowned in the canal since 1997, it has been called "the Most Dangerous Body of Water in the U.S."[2]
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[edit] History
The All-American Canal was authorized along with the Hoover Dam by the 1928 Boulder Canyon Project Act and built in the 1930s by the United States Bureau of Reclamation and Six Companies, Inc..[3] Its design and construction was supervised by the Bureau's then chief designing engineer, John L. Savage and was completed in 1942.[4]
[edit] Operations
[edit] Irrigation
The Bureau of Reclamation owns the canal, but the Imperial Irrigation District operates it. Water for the canal is diverted at the Imperial Diversion Dam. The All-American Canal feeds, from east to west, the Coachella Canal, East Highline Canal, Alamo River, Central Canal, New River Canal and the Westside Main Canal. These six main branches of the canal and a network of smaller canals gradually reduce the flow of the All-American Canal until it ends at a small drop in the western Imperial Valley where it drains into the Westside Main Canal. The main canal is 82 miles (132 km), with a total drop of 175 feet (53 m), a width of 150 feet (46 m) to 700 feet (210 m) and a depth of 7 feet (2.1 m) to 50 feet (15 m) The canals get smaller as they run west because they carry less water.
[edit] Power
Eight hydroelectric power plants have been constructed along drops in the All-American Canal system. Drops 1 through 5, Pilot Knob, East Highline and Double Weir are located on the All-American Canal. Another power plant, Turnip, is located on the Central Main Canal branch. The power plants are all relatively small and have a combined capacity of 58 MW. Electricity generation is dictated by water delivery needs. There is also a 7.2 MW pumped storage plant at Senator Wash Dam. Water from the Senator Wash Reservoir is released when water needs exceed flows at Parker Dam.
[edit] Runoff
Runoff from the farmland irrigated by the All-American Canal make up most of the flows in the Alamo River and New River, both of which drain into the Salton Sea, now providing most of its water.[citation needed][5] The rest is from smaller rivers and drainage systems. Historically, the Salton Sea had been periodically flooded by extreme Colorado River floods and usually dried up before being reflooded. If not for the All-American Canal, the Salton Sea would have likely dried up long ago.[citation needed] The system transports silt, selenium and salts from the Colorado River into the Salton Sea. Because there is no outlet to the ocean, these salts and minerals are concentrated by evaporation.[6]
[edit] Water withdrawal and usage
Total water use in the United States for 2000 was determined from estimates of water withdrawals for the eight categories of public supply, domestic, irrigation, livestock, aquaculture, industrial, mining, and thermoelectric power (fig. 1). Total freshwater and saline-water withdrawals for 2000 were estimated to be 408,000 Mgal/d, or 457,000,000 acre feet (564 km3) per year (table 1). Freshwater withdrawals were 85 percent of the total, and the remaining 15 percent was saline water. Estimates of withdrawals by source indicate that for 2000, total surface-water withdrawals were 323,000 Mgal/d, or 79 percent of the total withdrawals for all categories of use. About 81 percent of surface water withdrawn was freshwater. Total ground-water withdrawals were 84,500 Mgal/d, of which 99 percent was freshwater. Nearly all (98 percent) saline-water withdrawals were from surface water.
Total withdrawals by category and State are listed in table 2. For 2000, the largest water withdrawals were for thermoelectric power and irrigation. Most water (195,000 Mgal/d) was withdrawn for thermoelectric power, of which 30 percent (59,500 Mgal/d) was saline. Illinois used the largest amount of freshwater for thermoelectric power (8 percent of the freshwater withdrawals for thermoelectric power). The largest saline withdrawals for thermoelectric power (41 percent) were in California and Florida. The largest freshwater withdrawals were for irrigation (40 percent of the total freshwater, or 137,000 Mgal/d). California used the largest amount of irrigation water and accounted for nearly one-quarter of the total irrigation withdrawals.
[edit] Relining project
Approximately 68,000 acre feet (84,000,000 m3) is lost annually by seepage from the All American Canal, especially where the canal crosses the great Algodones Dune Field, a portion of which is visible extending from top to bottom in the center of the satellite image above. Additionally, dune sand is constantly blown southeast into the canal. As part of California’s Colorado River Water Use Plan, 37 kilometers (23 mi) of the canal are being lined to prevent water loss by seepage.[1] Some Mexican farmers have protested this lining project because the seepage from the canal allows them to irrigate their farms with groundwater replenished by the canal, however their claims were dismissed by a U.S. court.[7]
[edit] In the immigration debate
Every year dozens of illegal aliens drown in the canal's swift current and deep water during their entry into the United States. There is an active proposal to install safety ropes across the canal to prevent drownings, but the board that oversees the canal has so far refused to string such ropes, as they are concerned that it would further encourage illegal immigration to the United States.[2]
To date, over 550 people have drowned in the canal, which has earned the canal the reputation of "the Most Dangerous Body of Water in the U.S."[8]
[edit] In popular culture
The canal was featured in the 1957 horror movie The Monster That Challenged the World.
[edit] See also
[edit] References
- ^ a b All-American Canal, California-Mexico border Portions of the public domain text of this US government article have been incorporated into this article.
- ^ a b Pelley, Scott (May 2, 2010). "The Deadly Passage of the All-American Canal". 60 Minutes. http://www.cbsnews.com/stories/2010/04/30/60minutes/main6448631.shtml?tag=currentVideoInfo;segmentTitle.
- ^ "Boulder Canyon Project Act". December 21, 1928. http://www.usbr.gov/lc/region/g1000/pdfiles/bcpact.pdf. Retrieved June 19, 2010.
- ^ http://books.nap.edu/html/biomems/jsavage.pdf John Lucian Savage Biography by Abel Wolman & W. H. Lyles, National Academy of Science, 1978.
- ^ http://www.saltonsea.ca.gov/about/about.htm Salton Sea Authority | The Sea's Vital Statistics
- ^ http://www.saltonsea.ca.gov/about/myth.htm Salton Sea Authority | Myths and Realities
- ^ "Court dismisses third action filed against canal", Imperial Valley Press, July 16, 2007.
- ^ "All American Canal - 60 Minutes Profile on 'Most Dangerous Body of Water in US'". National Ledger. May 3, 2010. http://www.nationalledger.com/ledgerdc/article_272631594.shtml. Retrieved May 5, 2010.
[edit] Sources and external links
- IID - All-American Canal map
- USBR - All-American Canal website
- From the Colorado River to the Salton Sea: The story of Imperial Valley's Water (slideshow)
- USBR - Senator Wash Dam
- The All-American Canal: Slipforming 72 Feet (21.9 m) Wide, GOMACO World, article about the relining project.
- "Digging the World's Biggest Ditch", October 1936, Popular Science
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Coordinates: 32°52′33″N 114°28′21″W / 32.875876°N 114.472448°W
