Lake Garda Water Quality Monitored as Climate Drives Algae Variability

According to Dr. De Francesco, responsible for water quality controls at Lake Garda, our reporting has “attributed… an overly optimistic character” that she considers entirely misplaced.

In particular, the doctor writes: “1) since I do not possess the powers of a fortune-teller, I am absolutely unable to know if there will be algae patches in 2001. 2) I do not agree with statements like ‘the lake is doing fine’ nor with predictions about its wellbeing. I have simply presented ten years of monitoring data that highlight a state of hydrochemical stability during the observation period and place the lake in an intermediate situation between high oligotrophy (low productivity) and low mesotrophy (medium productivity).”

Data Analysis and Conclusions

These data seem to demonstrate that annual climatic conditions significantly impact the lake’s productivity, making it more abundant in years characterized by cold, windy winters that cause complete circulation of the water column; in these years, nutrients confined to the bottom become available in the surface layers, promoting greater algal development (this occurred in 1991, 1999, and 2000).

She further communicated that in 2001, the monitoring conducted so far has not shown evidence of complete water circulation.

Final Considerations

The report concluded with a call to remain vigilant regarding nutrient ingress into the lake. It is true that Dr. De Francesco did not rule out the return of greenish patches.

She said these are caused by a phenomenon that did not occur and likely will not happen again. She repeats that there is stability, as the climatic variations recorded over the years have balanced each other out, ensuring a good equilibrium for the lake.