Trace amounts of a toxin produced by algae blooms were detected in raw water entering the Port Rowan treatment plant last summer.
On July 24 and Aug. 6, microcystin levels in Port Rowan registered above the provincial standard of 1.5 parts per billion. Both samples tested at 1.7 parts per billion, prompting alerts to Dr. Shanker Nesathurai, Norfolk and Haldimand’s medical officer of health, the Ministry of the Environment, Conservation and Parks, and the province’s Spills Action Centre.
Details of the contamination are contained in Norfolk’s 2020 Drinking Water Summary Report, which was presented to Norfolk council on March 9. In both instances, microcystin returned to acceptable levels upon further testing and no further action was required.
Authorities monitor microcystin because – in sufficient amounts – the toxin can cause a wide-range of serious health effects. These include abdominal pain, headache, sore throat, diarrhea, respiratory problems and liver symptoms.
By law, public works staff are required to produce annual reports on the performance of water-treatment plants under their care. This includes a summary of “adverse water quality reports.”
“During this reporting period, thousands of water samples were analyzed for a wide range of parameters to ensure the safety and integrity of the water Norfolk County supplies to its consumers,” Larry Conrad, Norfolk’s director of environmental services, says. “On some occasions, these samples exceeded established criteria or maximum allowable concentrations.
“None of these exceedances posed any significant health risk nor jeopardized the safety of the county’s water supply. All adverse results recorded during the 2020 reporting period were handled appropriately and the actions taken by the water works operators restored the water systems to normal operations. Most were considered to be false positive as follow-up testing produced negative results.”
A common event in these updates involves deficient chlorine levels. Two samples in Norfolk last year did not meet the provincial standard of 0.05 micrograms per litre. These occurred in Port Rowan on Aug. 4 and in Port Dover on April 4.
In an unusual development, a chemical imbalance in the opposite direction was detected at the water-treatment plant in Delhi Sept. 16. That day, a sample was found to be fluoridated beyond the upper limit of 1.5 millograms per litre. The excess fluoridation was reported to Nesathurai, the Ministry of the Environment, Conservation and Parks, and the Spills Action Centre.
In cases of insufficient chlorination or excess fluoridation, the solution is flushing the system and re-testing until water chemistry returns to normal. In these three instances, there were no reports of adverse impacts on the wider community.
An adverse event was also recorded at the water-treatment plant in Waterford on May 13.
In this instance, coliform bacteria – the pathogen that caused death and injury in Walkerton in 2000 and led to an over-haul of water-quality standards in Ontario – was detected during a weekly sampling.
This too was reported to the Haldimand-Norfolk Health Unit. Plant operators double-checked chlorine levels and conducted further tests. Subsequent samples met the provincial standard and no further action was required.
The 2020 report says no adverse events were registered at the water-treatment plant in Simcoe.