All-American Canal

View of about 15 kilometers (9.3 miles) of the All-American Canal just west of Yuma, Arizona. Note North is to lower left.

All-American Canal near Algodones Road

The All-American Canal is an aqueduct that conveys water of the Colorado River into the Imperial Valley in California. It is the valley's only water source, and replaced the Alamo Canal, which was located mostly in Mexico. The All-American Canal provides drinking water for nine cities and irrigates over 500,000 acres (200,000 ha). It is the largest irrigation canal in the world, carrying up to 26,155 cubic feet per second (740.6 m³).

Background

The All-American Canal was built by the United States Bureau of Reclamation in the 1930s and was completed in 1942. 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, Central Canal and the Westside Main Canal. These four 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 to 700 feet (210 m) and a depth of 7 to 50 feet (15 m) The canal gets smaller as it runs west because it carries less water.

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.

Runoff from the farmland irrigated by the All-American Canal make up most of the flows in the Alamo River, both of which drain into the Salton Sea, providing 85% of its water.^{[citation needed]} The rest is from smaller rivers and drainage systems. If not for the All-American Canal, the Salton Sea would have dried up long ago, returning to its natural state.^{[citation needed]} Unfortunately, the runoff carries fertilizers, pesticides and salts into the sea and creates an unstable ecology.

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 thousand acre-feet 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.

Relining project

Approximately 6,800 acre feet (8,400 dam³) 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 astronaut 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 miles) of the canal are being lined to prevent water loss by seepage. A recently opened sector parallels the old canal (image left), and new lined sectors are under construction (bright lines, center). Engineers have sited new sections of the canal to avoid the worst areas of dune-sand invasion, so that the new configuration will be significantly cheaper to maintain and operate. ^[1]

Note that a new road crosses the dunes and marks the U.S.-Mexico border, part of border fence construction efforts. ^[1]

See also

All-American Canal Bridge

References

Sources and external links

• IID - All-American Canal map
• USBR - All-American Canal
• USBR - Senator Wash Dam

Coordinates: 32°52′33″N 114°28′21″W / 32.875876°N 114.472448°W / 32.875876; -114.472448