Beach water quality can change with weather

(Posted: July 11, 2016)

By Greg Mayne
Environment and Climate Change Canada

"Let’s go to the beach!" is a phrase often heard on a hot Ontario summer day. Before you can pack up and head to one of the many Lake Huron southeast shore beaches, you may want to check if there is an advisory for your favourite beach.

Beach water quality can change quickly depending on the amount of rainfall and varying sources and levels of pollutants. Bacteria such as E. coli (Escherichia coli) cause the most concern among health officials and beachgoers. Escherichia coli or E. coli refers to a large group of bacteria naturally found in the intestines of warm-blooded animals including people. Some strains, such as E. coli O157: H7 can lead to sickness such as stomach cramps, diarrhea, and vomiting. Infection with this strain of E. coli can cause kidney failure and can sometimes be fatal.

Municipal health units are responsible for monitoring public beaches and when test results show elevated E. coli concentrations, beaches remain posted until samples indicate safe levels.

Figure 1: Percentage of days beaches are open and safe for swimming along the southeast shore of Lake Huron.

Beach advisories are a State of the Great Lakes indicator. A closer look at beach water quality by Environment and Climate Change Canada shows that southeast shores beaches typically remain open and safe for much of the swimming season (Figure 1), with some beaches open for the entire season. No beaches, however, were open 100 per cent of the swimming season in 2014 according to a recent analysis (Figure 2). Huron County Health Unit’s Beach Water Monitoring Report (2014) shows deteriorating nearshore water quality at Port Albert, Port Blake, Houston Heights, as well as some other beaches in the county.

Figure 2: Proportion of beaches that are open and safe for swimming for a given percentage of the swimming season along the southeast shore of Lake Huron.

You can find detailed information on beach monitoring and beach health reports on the Huron County Health Unit website (

Primary sources of E. coli from wildlife and human activity include guano from geese and gulls, faulty septic systems, and stormwater runoff from urban, farm, and rural non-farm sources. Groundwater, rivers, and small creeks also act as conduits for pollutants like E. coli and many non-point sources (NPS) of pollutants like excess sediments, fertilizers and chemicals that enter and degrade nearshore water quality and beaches.

Non-point sources of pollution are complicated and elusive but represent a growing threat to the environment and public health. Because NPS pollution originates from the combined actions of many individual citizens and businesses, their close involvement and participation in addressing the issue is absolutely essential.





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