Lake Garda’s Water Turns Green Amid Algae Bloom, Experts Warn

Paolo Matteotti, the environmental councilor of Margherita leading the municipal task force fighting the periodic foams produced by the Ponale power plant (which also poses a significant aesthetic problem along the lakeshore), has recently been unable to ignore the phenomenon of anabaena, the deadly greenish algae that during the day drifts in long clusters across the Riva golf and in the evening shelters in the small harbors, creating a poor spectacle.

“There is no doubt that we are experiencing a constant and accelerating worsening of the lake’s coloration,” explains Matteotti. “Last year, I already issued a warning because the well-known ‘blu Garda’ was becoming a thing of the past. But I didn’t think the situation could deteriorate so drastically.”

The water’s turbidity these days has never been seen before. The water appears more green than blue. The algae banks of anabaena are undoubtedly the cause, and it is also certain that this is not related to harmful pollution.

However, knowing that the water remains suitable for bathing no longer suffices; the aesthetic aspect — including the absence of odors (these algae emit a disgusting rotten smell) — is too important for tourism and the cultural traditions of the lake.

If algae are proliferating, it means nutrients such as nitrogen, phosphorus, and potassium are increasing. Why are these last nutrients rising? We need to find out: I believe climatic factors certainly play a role, but I also consider human activities to bear responsibility.

It’s not easy, but in my opinion, it’s necessary to rethink large-scale water purification projects; probably those implemented in the 1970s, when Garda was at the forefront, are no longer sufficient.