• A Bacterial Water Quality Investigation of Canyon Lake

      Horak, W. F.; Lehman, G. S.; Department of Watershed Management, The University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1974-04-20)
      Fecal coliform counts in relation to number of swimmers along with fecal streptococci counts of water samples from Canyon Lake in central Arizona are reported. The presence of swimmers was related to an increase in fecal coliforms which was attributed to organisms shed from the swimmers and from agitation of the bottom sediments, consequently dispersing much of the bacteria contained in the benthos. From sampling of the swimming areas it was determined that livestock waste was the primary source of pollution (a greater number of fecal streptococci was found than fecal coliforms), but this interpretation could be misleading due to the higher survival rate of fecal strep than that of fecal coliform organisms.
    • Economic Alternatives in Solving the U. S.-Mexico Colorado River Water Salinity Problem (invited)

      Martin, William E.; Arizona Agricultural Experiment Station, the University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1974-04-20)
      A proposed desalting plant is an engineering solution to the effects of a problem which could have been avoided and even now could be reduced on the farm. Water costing $125 per acre-foot will be delivered to Mexico to grow wheat, cotton, garden crops, alfalfa and safflower, of which the average value added per acre-foot was estimated at $80 for cotton and garden crops and $14 for wheat, alfalfa and safflower. The U.S. government, instead of building the desalting complex, could accomplish its purpose just as well by paying each farmer in the Yuma area, in return for the farmers reducing their drainage flow by whatever method they see fit, $114 per acre per year for the next 50 years. With proper management on the farm, the costs of managing salinity need not be high.
    • The Effect of Development on Groundwater in the Parker Strip

      Everett, L. G.; Schultz, T. R.; Department of Hydrology and Water Resources, University of Arizona, Tucson, Arizona (Arizona-Nevada Academy of Science, 1974-04-20)
      The 14.6 miles of the Colorado River bounded by Parker Dam and Headgate Rock Dam has been referred to as the Parker Strip. This river reach has become a high use recreation area during the past decade with 4,000 permanent residents and as many as 120,000 water enthusiasts on long weekends. The riparian area of the river is heavily clustered with mobile homes, marinas and public beaches. The means of sewage disposal is exclusively via septic tanks. Recent surveys by the Environmental Protection Agency, Arizona State Department of Public Health and the University of Arizona have localized surface water bacteria levels that may indicate a developing groundwater problem. The geohydrology of the area indicates that the septic tanks are located in Post -Pliocene Colorado River deposits. The deposits are quite thin and relatively narrow. Since the deposits are locally derived sands and gravels, the horizontal hydraulic conductivities are such that a relatively short flow time to the river may result. Intensive evaluation of the degradation of the water quality in these deposits is needed to determine if the ground water supply was jeopardized by septic tank systems.
    • United States-Mexico Water Agreements and Related Water Use in Mexicali Valley: A Summary

      DeCook, K. J.; Water Resources Research Center, The University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1974-04-20)
      A summary is given of interrelated, technical and institutional events concerning the Colorado River which took place between the United States and Mexico from 1849 to 1974 with emphasis on the 1961-1974 period. Until the treaty of 1944, Mexico had had no guarantee of a specific annual quantity of water, but in the years after 1945, when a guarantee of 1.5 million acre-feet per year was established, more than that amount was available for use. Salinity problems arose, and in 1965 an agreement for a 5-year plan for alleviating the technical and political difficulties surrounding the salinity question was made. In 1973 it was agreed that the United States would build, within approximately 5 years, a facility for desalting the saline drainage water entering Mexico. Fulfillment of the technical provisions for this agreement requires, in any event, the timely provision of federal funds to construct and operate the physical works. The several states should receive assurance that their rights and those of their respective water users will not be impaired within the legal operation of the agreement.