Lower Colorado Region comprehensive framework study of water and land resources : summary report, June 1971

UUM_LowerColoSum_page_011

WATER REQUIREMENTS AND RESOURCES In 19659 the three primary sources of water available for use in the Lower Colorado Region were: a portion of Colorado River flows delivered at Lee Ferry, Arizona; local runoff; and local ground water supplies. See summary of water requirements and supply on page 36. Allowing for all losses, depletions, and exports and excluding ground-water overdraft, the total water supply available for use in the Region was 5.75 million acre-feet in 1965 and is projected to decrease to 4.02 million acre-feet in 2020 as a result of increased depletions in the Upper Basin. Total water requirement (withdrawals) for the Region is projected to increase from the 1965 base of about 10.1 million acre-feet to about 13.0 million acre-feet in year 2020. Total water consumed (depletion) is projected to increase from 5.8 million acre-feet in 1965 to about 8.5 million acre-feet in 2020. In 1965, ground-water reserves were being overdrawn (depleted) at a rate of 2.5 million acre-feet annually due largely to a lack of facilities for enabling the Region to utilize its share of Colorado River water. In the absence of an imported water supply, the ground-water overdraft will continue and the regional water deficiency is projected to reach 4.5 million acre-feet annually by year 2020. Until augmentation of regional water supplies is accomplished and/or salinity control measures are installed, the increased use of water in the Colorado River Basin will result in farther quality degradation of the Colorado River. Maintenance of an acceptable level of water quality is vital to the economy, environment, and general well-being of the people of the Region. Presently deficient water supplies and the probable cost of future imported water dictate maximum water utilization, including reuse or recycling. 11