Mori–Torbole tunnel

The Mori–Torbole Tunnel is a diversion tunnel completed in 1959 between the Italian towns of Mori and Nago-Torbole to connect the Adige river with Lake Garda. Its function is to reduce water levels in the river upstream of the province of Verona by discharging excess water into the lake. The tunnel reduces the risk of flooding in Verona and environs from once every seventy years to once every two centuries. To increase the level of Lake Garda by 0.4 inches (1.0 cm), the tunnel must divert about 130,000,000 cubic feet (3,700,000 cubic metres) of water. When the tunnel is open, the temperature shock and inflow of mud caused by the sudden influx of the Adige's water endanger the lake's fish populations, although the lake's larger volume is able to absorb large quantities of extraneous water into itself. For these reasons the tunnel is used only on the rare occasion when there is a flood risk in the Veronese basin.