24-hr hotline:
218-725-7724
How is beach water tested
Fecal contamination is determined through grabbing and analyzing
beach water samples.
Iced samples are taken to a certified local
laboratory and processed within 6 hours. Once at the lab, water
samples are funneled onto a filter, and the filter is aseptically
transferred to a Petri dish where a media is present to encourage
bacteria growth. The Petri dishes are then incubated
for 24 hours to stimulate growth. If fecal indicator bacteria (E.
coli or fecal coliform) were present in the water sample, then
bacteria colonies will have grown on the Petri dish. The level of
fecal contamination at a beach is determined by the number of colonies
present on the Petri dish.
Quality Assurance Project Plan - Minnesota Lake Superior Beach Monitoring Program (pdf - opens in new window)
