In Northern Italy, the groundwater resources provide
the majority of the drinking-water supply; however, the
increasing chemical contamination of most of aquifers
makes lake water an important alternative supply for
drinking water use. Some lake water mutagenicity
monitoring programmes were undertaken to evaluate
some important drinking-water supplies, such as the
lakes Como, Maggiore and Garda [7,8,13]. The highest
mutagenicity was observed in the samples from lake
Como [8]. The results from lake Como indicated the
existence of a possible source of industrial pollution,
coming from the inlet of the Cosia stream. This has