Garda Lake Algae Toxins Under Control, Water Safe, Authorities Confirm
Now, the results of analyses performed by the Laboratorio dell’Istituto Superiore della Sanità also confirm, as Bresciaoggi already reported yesterday, that the situation with toxic algae is completely under control. Therefore, there is no danger to human health. The official confirmation comes from Angelo Benedetti, head of the Distretto sanitario 11 del Garda, which has jurisdiction over public health and hygiene matters in the Garda area.
Monitoring and guarantees on water quality
“We are preparing a letter to send to the mayors of the lakeside towns to inform them of this news: we first gave a sort of ‘priority’ to the press to reassure local populations immediately after some alarms,” explains Benedetti. “We have, together with the Laboratorio di Sanità Pubblica dell’Asl di Brescia and the Dipartimento di Prevenzione, developed a series of checks, and then the results arrived.” What guarantees can you provide to citizens, especially those who consume water drawn from Lake Garda, considering that algae toxins could be near the lake intakes? “A premise should be made. To assess water conditions, complicated tests are carried out at the Laboratorio dell’Istituto Superiore della Sanità in Rome.
“There is no specific regulation,” emphasizes the director of the Garda district, “but based on scientific studies and research, we know that the risk of the presence of a toxin relates to the number of algal cells present in one liter of water.” Alright, but then how do you determine if there might be a real threat to public health? “From the cell count I mentioned earlier,” recalls Dr. Benedetti, “the threshold not to be exceeded is 5 million cells per liter.” And what did the analyses from the Brescia laboratories and those of the Istituto di Sanità report? “That this threshold was neither approached nor exceeded.”
However, during peak algae bloom periods on the lake surface, the concentration of toxic cells can reach extremely high peaks, even up to 100 million cells per liter! But these high concentrations very rarely “poison” the water distribution systems and lake intakes of many lakeside municipalities drawing from Garda: Sirmione, Desenzano, Moniga, Manerba, etc. This is because the aqueducts draw water well below the surface, between 30 and 60 meters deep. At those depths, Benedetti explains, the number of toxic cells drops significantly, down to about 500,000 per liter, compared to the alert threshold, which, as we reiterate, is 5 million.
Furthermore, the water is treated, either with ozone (as in Desenzano) or with hypochlorite (as in Sirmione). The better the filtration system used, the greater the guarantee of drinking water safety. “If the municipalities want a peaceful future, it is advisable that they improve, where necessary, their lake water intake systems,” Benedetti concludes.
