Water Monitoring

Measuring water quality

In Ontario, the Ministry of the Environment has set Provincial Water Quality Objectives, establishing thresholds for water pollutants including nutrients such as phosphorus, and pathogens (bacteria) such as E.coli, along with many other parameters.

Phosphorus concentrations should not exceed 20 micrograms per litre or 20 parts per billion (ppb). E.coli measurements should not exceed 100 E.coli per 100 millilitres of water (the level at which beaches are posted as unsafe). In the Kawartha Lakes, counts over 50 E.coli/100mL are considered somewhat high and are cause for re-testing.

Janice Sommerville


On Clear, Ston(e)y and White Lakes, more than a dozen dedicated KSLA volunteers collect water samples and check water clarity at more than 30 locations, many times throughout the summer. Water samples are analyzed for phosphorus, E.coli and other contaminants.

Results are then provided to the Ministry’s Lake Partner Program, government agencies, lake associations, academic researchers and environment organizations.

The Environment Council for Clear, Ston(e)y and White Lakes uses the data to help in its work of protecting and improving water quality.



Water monitoring results

Kathy Macarther

In general, the KLSA has found that phosphorus levels in parts of our lakes can exceed 20 ppb, particularly in July and August. These higher levels come mostly from human sources such as upstream sewage systems and agriculture, as well as faulty septic systems and fertilized lawns around the lakes. Natural sources, including soil erosion, decomposing aquatic vegetation and existing lake sediments also contribute. The water in Upper Stoney Lake tends to have lower phosphorus levels than Stony, Clear and White Lakes, because it receives low-phosphorus water from Jack’s and Eel’s Creeks, but phosphorus continues to “fertilize” aquatic weeds and algae.

Elevated E.coli readings have been reported at times in all three lakes. These higher E.coli reading are usually found in areas frequented by waterfowl, but also occur in areas of high human use, indicating that faulty septic systems and discharges from boat holding tanks are culprits.

To learn more about Water Monitoring results, go to klsa.wordpress.com.

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