The thresholds for Escherichia coli and intestinal enterococci, fecal contamination germs, are set at 900 CFU (colony forming units) and 330 CFU per 100 milliliters of water respectively to qualify the water quality as “satisfactory”. These thresholds will probably be exceeded during and after heavy rain days.
“The swimming will indeed always be subject to weather risk,” says Samuel Colin-Canivez. “But it’s just as true in Marseille for the Mediterranean. Just as we don’t windsurf without wind, or ski without snow, we won’t swim after stormy episodes. It’s the same principle. But it’s less intuitive.”
