Resumo -O presente trabalho avaliou a qualidade das águas subterrâneas na área urbana do município de Barreiras-BA, através de dois métodos de exames bacteriológicos (tubos múltiplos e colitag), para comparações de resultados e espécies nitrogenadas, que são parâmetros que indicam contaminação por esgotos (amônio, nitrito e nitrato). As coletas foram realizadas em 20 poços, distribuídos em rasos e profundos, com quatro campanhas para os exames bacteriológicos e duas para as espécies nitrogenadas, em época de chuvas e de estiagem. Dos resultados bacteriológicos, de 80 amostras analisadas, 65 % apresentaram-se insatisfatórios, que pode estar relacionado ao aspecto construtivo, localização do poço e variações sazonais, e com resultados dos dois métodos muito semelhantes. Nas espécies nitrogenadas, somente nos poços rasos, o íon amônio ultrapassou
ASSESSMENT OF BACTERIOLOGICAL QUALITY AND NITROGEN SPECIES OF GROUNDWATER OF WELLS IN THE URBAN AREA OF BARREIRAS-BAAbstract -This present study evaluated the quality of groundwater in the urban area of the municipality of Barreiras-BA through two methods of bacteriological tests (multiple tubes and Colitag), and nitrogen species, which are parameters that indicate contamination wastewater (ammonium, nitrite and nitrate). Samples were collected in 20 wells, distributed in shallow and deep, with four campaigns for bacteriological tests and two for the nitrogen series in the rainy season and summer. Bacteriological results of 80 samples analyzed, 65 % exhibited unsatisfactory , which may be related to the constructive aspect, bad location, seasonal variations and results of two similars related methods. In nitrogen species, only in shallow wells, the ammonium ion exceeded the Maximum Permissible (1.5 mg L -1 N-NH4 + ), in the deep, were within the standards. Nitrite, both in shallow wells as in the deep, attended Governing Law and how much nitrate in shallow wells, 83% exceeded the VMP (10 mg L -1 N-NO3 -) and deep, with values ranging from 4,0 to 14,43 mg L -1 N-NO3, which are warning values. The most of these wells is in the urban area of more ancient occupation of the city.