The distribution of the studied pollutants throughout the monitored region did not follow geographical gradients. Nevertheless, the effect of land uses on chemical pollution seems evident, especially when these compounds come from point sources like urban or agricultural activities. However, it is not possible to establish this kind of relationships in the case of other compounds with a diffuse source origin. In spite of the relatively low concentrations of PAHs, pesticides and herbicides in the lakes of this widely anthropized area, it is extremely important to pay attention to land use management in order to avoid the deterioration of these vulnerable aquatic ecosystems.