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Notes: The Tucson, Arizona, metropolitan area has 450,000 inhabitants and is expected to have nearly 800,000 inhabitants by the year 2000. Tucson is totally dependent on ground water drawn from two basin aquifer systems for its water supplies, as are agricultural, mineral and industrial operations in the area.Municipal, agricultural, mineral and industrial ground-water withdrawals in the two basins amount to some 376,000 acre-feet per year (AFY). Dependable ground-water supplies in the two basins amounts to about 80,000 AFY. Thus, the two aquifer systems are overdrafted by approximately 296,000 AFY, 80 percent of which is by irrigation agriculture.In Arizona, ground water belongs to the owner of the land overlying the aquifer. To ensure adequate ground-water supplies, the City of Tucson has been purchasing and retiring farmlands in one of the basins. However, litigation that reached the Arizona Supreme Court led the Court to rule that the City could pump only 2.4 AFY per acre of farmland retired. The City has retired about 12,000 acres in the basin and in 1978 withdrew some 20,000 AFY of ground water for municipal use.Retiring these farmlands to secure water rights impacts on area economy and creates weed problems for farmers who own land near the retired lands. The City of Tucson budgets about $50,000 annually for weed control.A possible alternative to retiring farmlands and to cultivating crops that require heavy irrigation is cultivating arid-adapted vegetation that has economic potential. Jojoba (Simmondsia chinensis) is a shrub native to the Sonoran Desert that appears to be an economically viable arid-land crop. It needs about 1.5 AFY per acre compared with traditional crops grown in the Southwest that have average needs of 4 AFY or more.The economic value of jojoba is based on the oil extracted from its seeds. It is a unique, unsaturated oil composed of nonglyceride esters consisting almost entirely of straight-chain acids and alcohols. Such oils are difficult to synthesize in commercial quantities, and the only known natural source is the sperm whale, an endangered species.If farmers in the basin cultivated jojoba, water use could be reduced by about 2.5 AFY per acre, from 4 AFY per acre for traditional crops to 1.5 AFY for jojoba. Even if the City of Tucson had to subsidize farmers at a rate of $40 per acre for the 10 years it takes jojoba to produce economically feasible yields, the City would save more than 50 percent of the cost to purchase and retire farmlands and still be able to draw water from the basin for municipal uses.This dual use of water in the basin would permit agriculture to continue its contribution to area economy while the City could continue meeting its water needs by piping water out of the basin into the metropolitan area. However, implementing this plan would require changing Arizona ground-water laws.

Notes: Rainfall and runoff in the Tucson, Arizona, urban area can be used to augment residential and municipal water supplies. Residential rainfall-harvesting systems include a catchment surface, collection and concentration components, separation and treatment units, storage capacity and distribution capability. A system to control runoff can divert water from urban washes for use in parks or other landscaped areas or can be used to enhance recharge to groundwater reservoirs. A reduction in flood hazards or peaks is a concurrent benefit of controlling and diverting runoff.

Notes: : Casa del Agua (Casa) in suburban Tucson, Arizona, was designed as a residential water conservation facility for applied research, demonstration of operational results, and transfer of technology to the general public. Starting in 1983, an existing residence was located, modified and retrofitted to acquire operational data on residential water use. Modifications included retrofitting existing landscapes and enlarging the rooftop to collect and harvest rainwater; separating blackwater and graywater lines; installing meters, low-water-use appliances and fixtures, and underground storage tanks for rainwater and graywater; and creating a public information center. Over the 13-plus years of actual operation, both the interior and exterior water use research results indicate large reductions in water use can be effected using water-saving devices andlor harvesting and reusing rainwater and graywater. Casa achieved over a 24 percent reduction in total water use and a 47 percent reduction in municipal water used compared to the typical Tucson residence. Overall water used was comprised of harvested rainwater (10 percent), recycled graywater (20 percent), and municipal water (70 percent). Casa's Information Center was visited by approximately 13,000 people from September 1985 through April 1999 and the research has been featured in local, national, and international media.

Notes: : Water supplies in Arizona are becoming increasingly limited because municipal, industrial, and agricultural consumption depletes ground water reserves by three million acre-feet annually.Additional demands are being created by electric power generation, particularly in northeastern Arizona where ground water pumpage is expected to escalate by sixfold during the next 10 years. The results of a study to determine the ease and feasibility of using satellite imagery as a tool in exploring for new sources of ground water are reported. Lineaments detected on Landsat images of two sites were mapped and correlated with well data in the two study areas by means of well centered grid model. The correlations developed between lineament density and water well data in the two study sites support the hypothesis that a relationship exists between regional geologic structure and the presence of ground water.

Notes: : Western state water resources are drawing increasing attention because of prolonged drought, pound-water overdraft and an ever-increasing awareness of insufficient Colorado River water to supply a growing population and meet industrial demand. Arizona is no exception, and the alarming decline in ground-water levels has prompted the Arizona State Legislature to adopt legislation establishing the Ground-Water Management Study Commission to recommend legislative action by 1979.This paper summarizes Arizona's ground water legislative history and discusses possible alternatives for change. The authors address specific issues facing the State and offer a set of possible Commission recommendations.

Notes: : A typical single family residence in Tucson, Arizona, was retrofitted to incorporate low-water-use fixtures and water reuse systems. The use of municipal water was reduced by 53 percent to 53 gallons per capita per day (gpcd) and total water use at the home was reduced by 33 percent to 74 gpcd.

Notes: : An index of residential water efficiency - a “W-Index” - can serve as a measure of effectiveness of water conservation features in the home. The index provides a calculated numerical value for each dwelling unit, derived from the number and kind of water-saving features present, including indoor and outdoor water savers and water harvesting or recycling systems.A W-Index worksheet, devised for on-site evaluation of single-family residences in the Tucson, Arizona, region shows that a nonconserving residence with all the water-using features would use 151,000 gallons per year or 148 gallons per capita per day (gpcpd), while the fully conserving model would use 35,300 gallons per year or 35 gpcpd and with water harvesting and graywater recycling systems would have a maximum W-Index of W-160. A Tucson water conservation demonstration home, Casa del Agua, received a rating of W-139, and field tests of about 30 homes in new Tucson subdivisions show values ranging from W-75 to W-100, indicating the incorporation of some water conservation in current new models.By adjustment of some climatic or water-use parameters, the W-Index format can be applied to various types of dwelling units or to other urban areas. The W-Index can be used by individual homeowners or builders to evaluate water efficiency of residential units, or by water providers or water management agencies as a device for promoting and achieving water conservation goals.

Notes: : Groundwater pumping constitutes approximately 100 percent of the water supply in the Tucson Active Management Area (AMA), Arizona. The current annual overdraft approaches 250,000 acre-feet, but the goal of the AMA is to eliminate the overdraft by the year 2025. Urban water reuse, if implemented by only 30 percent of the area's projected population, would reduce the annual ground-water overdraft by 25,000 acre-feet.

Notes: Like many States in the American West, Arizona is flooded with conflicting claims to water, a very scarce resource. Conflicts arising from water-rights claims by mining, agricultural and municipal entities are a traditional part of life in Arizona. Indian water-rights claims, however, are a relatively recent development which introduce a significant and troublesome new factor into an already delicate water-supply-and-demand management matrix. These claims are the topic of this paper.Any discussion about legal bases of Indian water-rights claims must begin with an understanding of the U.S. Supreme Court's 1908 decision in the Winters case. In that decision the Court ruled that the U.S. government impliedly reserved water rights for the Indians of the Fort Bethold Reservation in Montana when it withdrew the lands from public domain. The Winters case and subsequent Indian water-rights litigation are reviewed and the impacts on Arizona water-rights claims are projected.Finally, the author suggests that the federal government must develop substitute water sources or augment water supplies for Indians if it is to fulfill its trustee role as defined in Winters doctrine adjudication. Five recommendations are presented for review in considering the possibilities of the two alternatives for government action relevant to solving complex water-rights conflicts in Arizona, recommendations which may be applicable to similar problems in other water-poor regions in the American West.

Notes: : Water hyacinth (Eichhornia crassipes L.) has shown to be effective in the treatment of municipal wastewater in a pilot study begun in January 1989 by the Pima County Wastewater Management Department and researchers associated with The University of Arizona's Office of Arid Lands Studies in the Sonoran Desert near Tucson. The influent pumped into the pilot facility's six raceways (ponds) typically has been treated secondary effluent diverted from a conventional treatment facility, although primary effluent from the same facility also has been treated. The Secondary Influent Treatment System has met the Arizona Department of Environmental Quality (ADEQ) tertiary standard for BOD5 and TSS of 10 mg/l for every month of its operation since March 1990; the Primary Influent Treatment System met the ADEQ secondary standard for BOD5 and TSS of 30 mg/1 for most of the 10 months it was in operation.