Lake Garda Water Levels Rise Despite Increased Outflow Measures

The water level of Lake Garda is causing considerable concern. It is steadily rising despite a recent doubling of outflow from 90 to 180 cubic meters per second. This maneuver was further increased by ten cubic meters per second at 6 p.m. on Friday, but at the same time, the sluice gate at Mori of the Adige River spillway was opened, discharging 50 cubic meters per second into the Garda basin. These measures are unlikely to balance the exceptional inflow and outflow caused by persistent rains across the entire Sarca-Garda watershed.

The situation has become critical also because the hydroelectric basins upstream of Garda, Molveno and Ledro, have already reached and surpassed their maximum capacity and cannot serve as reservoirs, thus preventing the discharge of Garda waters through the Mincio River. The activation of the Adige-Garda spillway, even for just 24 hours, as assured, and the release of large quantities of water into the lake increase the risk of a scenario similar to that of autumn 1960, when lake levels reached an extraordinary 212 centimeters above the Peschiera hydrometric zero.

Consequences of the historic floods

The flood of 1960 caused flooding in nearly all towns of central and lower Garda, as the outer docks along the Lazise, Bardolino, Garda harbors, and some streets of the three towns were half a meter below the water level. At that time, as now, it appears that, despite the occurrence of exceptional events, there was a lack of precise coordination in managing entry (Adige-Garda tunnel) and exit (Salionze dam) operations.

In 1960, the lake’s water level reached the highest point ever recorded in the 20th century, second only to the maximum of 217 centimeters in 1879. However, 120 years ago, the Garda basin was still a natural, unregulated environment, unlike since 1949 when it has been artificially managed. During a rainy summer in 1960, when the lake was at +128 centimeters mid-September, instead of the planned +70 centimeters above the hydrometric zero, an autumn with heavy rains followed, increasing the level by over two meters within about twenty days. This was helped by the opening, for the first time, of the Adige-Garda spillway and the fact that, at the time, the Mincio could not discharge more than about 100 cubic meters per second.

Devastations and parallels with the current flood

The greatest damage was not caused so much by the high water levels but by the storm that struck during the night of October 14-15, 1960, especially impacting the Brescia Riviera of Garda. The effects of the flood extended downstream, as the discharge of water through the Mincio had to be raised beyond safety limits, resulting in river overflows and flooding of territories in the municipalities of Volta Mantovana, Goito, and Marmirolo.

This situation threatens to recur today, given that lake waters are again exceeding safety limits, the reservoirs of hydroelectric basins are at very high levels, and current weather conditions are unsettling. The Po River, in constant flood, could hinder the outflow of water from the Mincio. The only positive note is that, under optimal conditions, the Mincio can discharge twice as much water—up to just under 200 cubic meters per second.