From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona / A mathematical model to simulate overland and channel flow using the finite element technique was adapted and applied to a small semi-arid rangeland watershed (2,035 acres) in the USDA Walnut Gulch experimental watershed in the Southwestern United States. The Holtan equation was used to estimate precipitation excess, and with the precipitation excess as input, the finite-element technique was used to route overland and channel flow. The program was structured with sufficient flexibility so that effect of land use changes either gradual or sudden, on runoff hydrograph could be estimated. Abstraction losses in the stream channel are accounted for. The simulation model predictions are compared with field data for several storms and the comparisons are satisfactory; however, improvements could be made with additional data on antecedent moisture content and better estimates of abstraction losses. Based on these comparisons, it is felt that the model can be used to estimate runoff hydrographs from ungaged watersheds in semi-arid regions.

From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona / A demonstration agrisystem located in an area receiving less than 250 mm rainfall annually has been constructed through a cooperative program between the City of Tucson and the University of Arizona. Mondell pine, aleppo pine, jojoba, grapes, eucalyptus, olives, and other crops were cultivated in a 4 ha NaC1 treated catchment system designed to concentrate rainfall on plants and channel excess water into a system of storage reservoirs. Evaporation was reduced from an 80 foot diameter above ground reservoir by means of 225,000 plastic film cans, at a cost of approximately 50 cents /ft². Data acquired from evaporation pans indicates a 50 to 70 percent reduction in evaporation of the stored water. Additionally, this research has provided data that 1) demonstrates the economic potential for agriculture of currently retired farmland, 2) investigates the feasibility of applying water harvesting method for agricultgural purposes in a semiarid region, and 3) evaluates water harvesting as an alternative to meet the ever increasing demand for water.

From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona / The area of study covers 26.5 square miles ranging from the confluence of Beaver Creek and Verde River to the north, to the confluence of West Clear Creek and the Verde River to the south. Ground water depths for 471 domestic and agricultural wells were obtained, and selected wells were field checked to insure accuracy of data. A ground water contour map was constructed from well data at a 1:24,000 scale with a 20 foot contour interval. Aquifer characteristics of the study area were obtained via pump test data. Aquifer characteristics were then plugged into a USGS 2-D computer model, which has been modified to give the best representation of the Verde aquifer. The 2-D computer program and the 1:24,000 ground water map will be useful predictive tools to prevent overdraft and poor well spacing as development of the study area leads to greater withdrawal demands.

From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona

From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona / A wastewater treatment is proposed. It is based on: 1. The assumption that the changes taking place during the transformation of wastewater into effluent are unidirectional processes, entailing a number of well- defined sequential stages, and 2. The knowledge that the aerobic bacterial populations present in wastewater are able to decompose efficiently the organic matter in the wastewater, given optimal conditions for their development. Preliminary experiments in which these assumptions have been tested showed the production of a high quality effluent, as measured by the conventional chemical, physical and public health standards. No pathogenic bacteria or human enteric viruses have been recovered from the effluent so produced. A comparison between the processes of the "conventional biological" and a "biodynamic" treatment will be presented.

From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona / The Pinetop-Lakeside area located in southeastern Navajo County, Arizona, has experienced several outbreaks of probable waterborne gastroenteritis. The many on -lot sewage disposal systems, thin soils and fractured crystalline rock aquifers make this area especially vulnerable to biological degradation of the groundwater supply. This study was designed to assess the extent of bacteriological and virological contamination of groundwater and relationships between indicatior bacteria, coliphages and human pathogenic viruses. Twenty different wells were selected and monitored for conforms, fecal conforms, fecal streptococci, coliphages, enteric viruses, and various physical and chemical properties of the water. Extensive microbial contamination of the groundwater was observed, which increased dramatically after a period of heavy rainfall. Almost 90% of all well samples contained coiform levels in excess of drinking water standards.

From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona / Ground water is an increasingly significant source of potable water that has traditionally been considered safe for human consumption without treatment. Although routinely monitored for the presence of coliforms, information concerning the non-coliform bacteria present in well water has been largely ignored. The purpose of this study was to demonstrate the ability of non-coliform, "naturally-occurring" bacteria to increase in number and persist in unamended well water. Water was collected from 19 continuously pumping wells throughout the Tucson basin and stored at in situ well water temperatures. Bacteria were enumerated using epifluorescent microscopy at predetermined intervals over a 30-day period. Greater than 3 log increases in bacterial numbers were noted after 24 hours of incubation. Maximum numbers were achieved after 3 days followed by a gradual decline ranging from 0.39-1.84 logs. Non-coliform, opportunistic pathogens have been isolated from Tucson well water. Their increase in number and survival in well water may impact the quality of untreated drinking water.

From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona / No previous studies have been conducted in the United States on the occurrence of human pathogenic enteric viruses in freshwater recreation areas. Recent epidemiological studies have shown a significant amount of gastroenteritis associated with swimming in recreational waters meeting current bacteriological standards. Evidence also suggests that the observed gastroenteritis has a viral etiology. This study was designed to determine the occurrence of enteroviruses in a heavily used recreational area during the summers of 1982 and 1983. Positively charged Zeta-plus filters were used for collection of virus samples which ranged in size from 67 to 210 gallons. Enteroviruses, including poliovirus type 1, were isolated from several samples. Coliforms and fecal coliform standards for recreational use were exceeded in several samples. It is possible that the presence of enteric viruses in this popular recreational area may be a source of enteric viral disease during the summer months.

From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona

From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona / Levels of nitrates in excess of the US EPA standard of 45 mg/l were found in well water south of Tucson, Arizona. Most groundwater in this area with high nitrate content is beneath lands presently or formerly irrigated. The highest nitrate contents are present in the upper several hundred feet of the aquifer suggesting a source at the land surface. Nitrate contents in water from most wells in the study area were less than 7 mg/l in the late 1940's, but by the mid-1960's the nitrate level exceeded 25 mg/l in most wells. In the summer of 1982, more than 12 wells exhibited water with a nitrate content exceeding 45 mg/l. Analytical techniques included assessment of pollution sources at the land surface, chemical indicators such as chlorides, nitrogen and oxygen isotopes, and evaluation of the hydrogeologic conditions in the study area. Sources of nitrate contamination included sewage effluent disposal into the Santa Cruz River, historical irrigation practices, septic tank area, and an abandoned hog farm.