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.

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

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 / Post-disaster studies of the October 1983 flood lead to serious questions concerning the applicability to southern Arizona of nationally standardized procedures for flood hazard evaluation. When the U.S. Water Resources Council method of determining flood flow frequency is applied to the Santa Cruz River annual peak flow record at Tucson for the period 1915-1982, the 1983 flood discharge is predicted to have an exceedence probability of less than 0.001. Hydro-climatological considerations suggest that such large floods occur much more frequently. The standard procedure for flood hazard zonation utilizes step-backwater calculations for the extant channel and valley floor geometry to route the discharges obtained from the standard flood flow frequency analysis. This procedure, as used in the Federal Emergency Management Agency flood insurance study, greatly overestimated the areas of overbank flooding along the Santa Cruz River as experienced in the 1983 flood. A detailed post-flood study was performed to assess channel change for reaches of Pantano Wash, Tanque Verde Creek, the Rillito, and the Santa Cruz River in the Tucson Basin. Bank erosion occurred as cutbank recession of actively migrating meander bends except where local areas of bank were preserved by revetments. Where revetments remained intact during the flooding they served to concentrate and enhance bank erosion in the unprotected reaches immediately downstream. From an overall river management perspective, piecemeal bank protection generates greater channel instability than does no protection at all.

From the Proceedings of the 1985 Meetings of the Arizona Section - American Water Resources Association and the Hydrology Section - Arizona-Nevada Academy of Science - April 27, 1985, Las Vegas, Nevada

From the Proceedings of the 1985 Meetings of the Arizona Section - American Water Resources Association and the Hydrology Section - Arizona-Nevada Academy of Science - April 27, 1985, Las Vegas, Nevada / Hydrologic and hydraulic design procedures developed by the Pima County Department of Transportation and Flood Control District were proposed for use by the Department of Transportation, Engineering Division of the City of Tucson, Arizona. These procedures were evaluated with respect to their reasonableness of approach and in comparison with other methods and existing data used to derive similar methodology and standards. The proposed criteria/methodology were found to be consistent with procedures used in other cities in the Southwest, and with the current state of the art in urban hydrology and hydraulic engineering practices and procedures. However, locally derived rainfall intensity -duration relationships were found to be superior to regionally based relationships, and minor modifications were suggested for channel design procedures.

From the Proceedings of the 1985 Meetings of the Arizona Section - American Water Resources Association and the Hydrology Section - Arizona-Nevada Academy of Science - April 27, 1985, Las Vegas, Nevada