Arrowhead Beach Park

Source Information

Swim Drink Fish staff and volunteers monitor recreational water quality along the shore of Lake Ontario during the summer months. The guidelines followed are the Operational Approaches for Recreational Water Guideline, 2018, set by the Ministry of Health and Long Term Care. Prior to 2018 beaches in Ontario were posted when the geometric mean of 5 samples collected within a 30-day period exceeded 100 E. coli / 100 mL of water, a standard derived from the Ministry of the Environment, Conservation, and Parks’ Provincial Water Quality Objectives. Water is sampled for E.coli and Total Coliform at all sites. The water is sampled once weekly from July to early September. Results are available 24 hours after samples are collected. Beaches are posted when the geometric mean of 5 samples collected within a given swimming area and within a 30-day period exceeds 200 E. coli / 100 ml of water or when a single-sample maximum concentration exceeds 400 E. coli / 100 ml of water. Test results are expressed in terms of colony forming units (CFU) of E.coli per 100 ml by using the TECTA B16 rapid microbiological testing instrument. In accordance with Ontario’s provincial recreational water quality standard, a beach is marked Green when geometric mean of 5 samples results are equal or below 200 E.coli / 100 mL water and below the single sample criteria of 400 E.coli/100ml. A beach is marked Red when the geometric mean concentration (minimum of five samples) is above 200 E.coli / 100 mL or above the 400 E.coli/100mL for a single sample. A beach is marked Grey when there are no current results or there is no available information. Results are posted as soon as lab results are available. Results will be communicated through the Swim Guide website and apps. Results are also available by email at georgia@swimdrinkfish.ca or by calling +1 (416) 861-1237.