Eutrophication of Piedmont Quarry Lakes (North-Western Italy): Hydrogeological Factors, Evaluation of Trophic Levels and Management Strategies

Quarry lakes resulting from alluvium extraction have excavation depths that can reach the shallow aquifer and extend beyond the piezometric surface. Similar to natural lakes, pit lakes are subject to eutrophication process, both during and after quarrying activity; during mining activity, the eutrophic level is strongly controlled by the excavation method. The present study describes the trophic status of several quarry lakes in the Piedmont plain (north-western Italy) that were evaluated by applying classifications from scientific literature. Most of the studied quarry lakes were mesotrophic or eutrophic, and a slight worsening of water quality was observed over time. In addition, the paper focuses on the pit lake water quality and pit dimension; it was shown that lakes with a larger depth and volume generally had a lower tendency towards eutrophication. At last some management strategies were suggested to achieve environmental sustainability.