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California's Water: Facts on "What's New on the Colorado River"

Background

Canals and aqueducts that bring Colorado River water to Southern California are a key component of the state’s backbone water infrastructure and an integral part of California’s water supply. Water agencies that rely on the Colorado have committed billions of dollars to develop water management programs as part of California’s overall strategy to live within its legal entitlement of 4.4 million acre-feet of Colorado River water per year.

In recent years, California has used as much as 5.37 million acre-feet (MAF) per year, even though its entitlement is only 4.4 maf plus 50% of any declared surplus. Growth in Nevada and Arizona are causing these states to use their full allotments of water, decreasing the surplus water available to California and putting more pressure on the state to live within the 4.4 MAF allotment. Programs to this end range from canal linings to water transfers to new groundwater storage projects, and are essential to achieving the region’s long-term goal of maintaining a reliable supply from the Colorado River.

History

  • 1922 CO River Compact allocated water among the river’s seven basin states. In addition to its allotted 4.4 MAF share, California was allotted half of all surplus water when available.
  • 1928 Boulder Canyon Project Act was authorized for the construction of Hoover Dam, the All-American Canal and Imperial Dam.
  • 1931, seven CA entities entered into a permanent contract for the distribution of CA’s 4.4 MAF. The contract specified that 3.85 MAF would go to irrigation districts for agricultural uses. These entities were as follows:
    • The City of San Diego
    • Coachella Valley Water District
    • Imperial Irrigation District
    • Los Angeles Department of Water and Power
    • Metropolitan Water District of Southern CA
    • Palo Verde Irrigation District
    • San Diego County

Key Facts

  • Length of River: 1400 Miles
  • Source of the CO River is in the Rocky Mountains
  • River ends in the Gulf of California in Mexico
  • States in the Upper Basin: Wyoming, Utah, Colorado, and New Mexico
  • States in the Lower Basin: Arizona, California, Nevada, New Mexico, and Utah
  • Lower Colorado River Watershed Area: 246, 000 square miles
  • Average Assumed CO River Annual Flow to Lower Basin at Lees Ferry: 15 MAF
  • Historic Yearly Flows:
    • High: 24 MAF
    • Low: 5 MAF
  • Amount of Water in an Acre-Foot: 326,000 gallons
  • Average Rainfall in Majority of Basin
    • 4 inches or less
  • Average Power Generated Using CO River Water: 12.2 trillion kilowatts
  • Amount of Colorado River Water Allotted to California: 4.4 million acre-feet plus 50% of any declared surplus
  • Amount of California’s Share of CO River Water Dedicated to Agriculture: 3.85 MAF
  • California Acreage Irrigated by CO River Water: 800,000 acres
  • California Irrigation Water Users:
    • Imperial Irrigation District
    • Coachella Valley Water District
    • Palo Verde Irrigation District
    • Bard Irrigation District and Indian Agencies

All-American Canal

  • Dimensions
    • Overall length 82 miles
    • Width 150-200 feet
    • Depth 7-20 feet
  • Capacity
    • From Imperial Dam to Siphon Drop Power Plant: 15,155 c.f.s.
    • From Siphon Drop Power Plant to Pilot Knob: 13,155 c.f.s.
    • From Pilot Knob to Drop No. 1: 10,155 c.f.s.
  • The All-American Canal is the Imperial Valley's lifeline from the Colorado River. Approximately 3.1 million acre-feet of Colorado River water is diverted annually into the All-American Canal and delivered to agricultural land and cities.
  • 70,000 acre-feet per year of water seeps out along a 23-mile section.
  • The new, lined section will result in the conservation of 67,700 af/yr.
  • The State of California is paying $135 million for lining the earthen portions of the canal with concrete, in exchange for some of the water saved. Costs above this amount will be paid for by the San Diego County Water Authority, which will receive the conserved water.

IID/San Diego County Water Authority Water Transfer Agreement

  • Largest ever transfer of water from agricultural to urban areas.
  • First 10,000 af flowed to San Diego in 12/03
  • Under the agreement, the water transfer increases to 200,000 acre-feet annually in year 19 (2022) and stays at that level each year thereafter. It has an initial term of 45 years and a renewal term of 30 years. The transfer represents a new supply of 12.9 million acre-feet of water for San Diego County Water Authority over the 45 or 75-year life of the agreement.

Lower Colorado River Multi-Species Conservation Program

  • Cost: $626 million, to be funded by AZ, CA, and NV
  • A habitat-based conservation program aimed at providing for the conservation of over twenty-seven species, including six that are currently listed as threatened or endangered under the federal Endangered Species Act and eleven species listed as threatened or endangered under the California ESA.
  • Specific measures include creation of 8,132 acres of habitat, the establishment of mesquite woodlands and cottonwood-willow riparian zones for birds and animals, and the formation of marsh and backwater areas for certain birds and fish. A fish rearing and stocking program also are planned to help increase populations of two endangered fish species.