WSP04095 - Laserfiche WebLink

Home Browse Search

- ~- -.J '-'~ - ~'} 2. Protective and Regulatory Pumping (Reclamation) The ground water reservoir underlying United States lands in the Yuma, Arizona. area is the same reservoir underlying contiguous lands in Mexico. Pumping on one side of the boundary affects the ground water reservoir on the other side. The pumping of water from wells located immediately north of the Southerly International Boundary separating Arizona and Sonora, Mexico, will provide accountable water deliveries to Mexico. In December 1972, Mexico commenced pumping ground water from a well field located immediately south of the International Boundary separating Arizona and Sonora. Mexico. Studies indicate the pumping draws water stored in the ground water reservoir underlying the Yuma area in the United States and in time will seriously affect the surface drain flows historically delivered to Mexico as part of United States' obligation under the 1944 Water Treaty. These flows had been about 125,000 acre-feet of drain flow and 15,000 acre-feet of canal wasteway flow annually. More recent annual flows total only about 105,000 acre-feet at the Southerly International Boundary and will gradually be reduced to about the 15,000 acre-feet of canal wasteway flow. Public Law 93-320 authorizes the Secretary to construct, operate, and maintain a well field for ground water pumping in a 5-mile zone adjacent to the International Boundary near San Luis, Arizona. The well field, known as the Protective and Regulatory Pumping Unit, would have the capacity to produce approximately 130,000 acre-feet per year. Water produced from the well field would be (1) delivered to Mexico for credit against the 'Treaty obligation and (2) used in the United States. The law also authorized the Secretary to acquire approximately 23,500 acres of private, State, and State leased lands within the 5-mile zone near the boundary. The purpose of this land acquisition is to limit agricultural development within the zone, thereby limiting ground water pumping to the 160,000 acre-feet per year as required by Minute No. 242 of the International Boundary and Water Commcission, United States and Mexico. About 10,000 acres of Reclamation withdrawn land are used to assist in this control. The ground water table within the 5-mile zone is expected to decline during the 50-year life of the Protective and Regulatory Pumping Unit. This decline will occur as a result of project pumping, Mexican well field pumping, and pumping of private wells. Water table drawdown from only project pumping over 50 years is predicted to be about 55 feet in the vicinity of Hillander "c" Irrigation District and between 5 and 20 feet in the southern Yuma Valley. The combined effects of both United States and Mexico pumping will result in a drawdown of approximately 110 feet in the vicinity of the Hillander "c" Irrigation District and from 20 to 60 feet in the southern Yuma Valley. Ultimate production in the 5-mile zone will be 160,000 acre-feet per year; of that, the amount to be delivered to Mexico is expected to be 125,000 acre-feet per year. This quantity, along with 15,000 acre-feet of wasteway flows, will furnish the necessary 140,000-acre-foot delivery at the Southerly International Boundary. The balance of the water available from the well field could be sold to other users in the area. wells, road. Contracts have been completed for construction of the first 21 a conveyance channel, appurtenances, and an operation and maintenance Future construction to complete the 35-well system and maintain the VII-4