The objective of this study was to evaluate the water quality of the Apodi lagoon, in the State of Rio Grande do Norte, Brazil, at points along its surface. The monitoring of the water quality is emphasized as it is under influence of the urban basin of Apodi and due to incorporation of material by the influx of continental waters that lead to eutrophization of the lagoon water in periods of extreme temperatures and precipitation. Systematic samples were collected from the lagoon water surface throughout its length. The electrical conductivity of the Apodi water varies along the surface, mainly in the west and southeast extremities. The water salinity increased with the beginning of the dry period and decreased after the rains. There is a great spatial variability in the physical and chemical characteristics, mainly for pH, CE, RAS and Na and Cl contents. In the lagoon, the most frequent ions were sodium and chloride, both for sample points and time of collection. The change in the bacteriological quality of water compromises the balneary of the Apodi lagoon, especially after the rainy season.
water resources; salinity; coliforms
