Lake Varese is positioned among the morainic hills of the alpine zone in the tall Lombardy lowland, the origin of the lake is tectonic while its excavation is of river nature, the actual form derives from the activity of the glacier Verbano. The lake is fed by underwater sources and by direct precipitations but the principal tributaries are the channel Brabbia, coming from the near lake of Comabbio, and the stream Tinella; the emissary is the river Bardello. Of historical and archeological interest the small islet Virginia, positioned in front of Biandronno, where there were found important rests of the Neolitic period, around 3.000 years ago.

The lake of Varese is living a long period of "eutrofizzazione" of its waters that, since the Sixties, it has assumed remarkable dimensions: it is a phenomenon of "enrichment of the waters in nourishing salts that it provokes typical changes like the increase of the production of the algas and aquatic plants, the impoverishment of the fish resources, the general degradation of the quality of the water and other effects that they reduce or they block the use of it (OECD, 1982)". The principal negative effects, due to this trial, are identified in the limited transparency of the waters, presence of bad odors in the zones of smaller circulation of the waters, episodic pestilences of fishes, release of nourishing from the sediments, imposing summer flowerings of algas kind, excessive presence of macrofit relatively to the reeds and the laminetis in the zones of Biandronno, Cassinetta and locality Schiranna.

In 1986 it has been on its way the lake collector of the lake on initiative of the "Consortium for the safeguard and the guardianship of the waters of the lake of Varese", with the intent to prevent the access in the lake of civil and industrial unloaded, carrying them toward a plant of purification "Varese-lake" to Gavirate on the river Bardello. During the years it coul be possible to ascertain a progressive diminution of the load of the phosphorus, principal responsible of the process of "eutrofizzazione". At the beginnings of the new millennium the "Center Common of Search European" of Ispra (CCR) has started interventions of "emunzione", in the deepest zones of the lake near Gavirate, and of "oxygenation ipolimnica", in the least deep zones in locality Schiranna, Cassinetta of Biandronno, Bodio Lomnago and Cazzago Brabbia, with the purpose to recovery faster the waters of the lake.