The general environmental conditions of Santa Giusta Lagoon, an important Sardinian coastal lagoon often affected by dystrophic crises, are examined. The study considers both the monitoring data collected over the past ten years on the relevant water quality parameters and the preliminary results on the structure and heavy metal content of the surface sediments of the lagoon. These data emphasised its elevated trophic level, due to the excessive presence of plant nutrients in water, and a relative low level of heavy metal contamination. At the moment, the eutrophy--brought about the urban and industrial wastes from Oristano and Santa Giusta--can be considered the main environmental issue of the lagoon