WATER-QUALITY PROBLEMS IN NOGALES, SONORA

This article presents the results of a transboundary water quality mon itoring program at the two Nogales area in the Arizona-Sonora border r egion. The program was carried out jointly in 1990 by U.S. and Mexican institutions. The results show pollution problems due to deficiencies in Nogales, Sonora municipal sewerage system, causing not only sewage spills in several parts of the city but also creating occasional tran sboundary problems. The results also showed potential illegal dumping of industrial hazardous waste (VOCs) into Nogales' municipal sewerage system. All of the organic compounds found in the sewage samples are s olvents frequently used by the border industry. Occasional brakes of p ipes spill the pollutants into the Nogales Wash, a water stream that r uns parallel to Nogales' main sewerage line. Samples of the municipal water system showed no traces of pollutants. However, two rounds of sa mples detected concentrations of VOCs in wells used to supply water by trucks to low income neighborhoods in Nogales, Sonora. ironically, th e pollution detected in these wells has a greater impact in low income groups of the city that pay three to four times more per liter of wat er they consume, than the rest of the inhabitants with clean water fro m the municipal system.