The existence of chromium in groundwater is a subject of great concern in the northwestera region of the State of São Paulo, where cities depend on groundwater resources for their only source of water. This paper attempts to characterize the areai extent of the chromium anomaly in groundwater in this region; to develop a geochemical study of water, sediments and rocks in the city of Urânia; and to define the relation between public health and the presence of chromium in groundwater for public consumption. Through the combination of data and the systematic study of chromium leveis in water, sediments and rocks, the following conclusions were drawn: the chromium anomaly is not only present in the city of Urânia, but also in other municipalities and districts in northwest São Paulo; the distribution of chromium concentrations is irregular, both in time and space; the source of the chromium is subject to discussion, despite strong evidence that it is natural. However, more in-depth studies are necessary; no relevant conclusions can be drawn about the problems caused by the chromium anomaly to the health of the population served by this water.
