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UPDATE: Potential Blue-green Algal Bloom in Williams lake NS

Blue-Green Algal Bloom Has Cleared

photo: Sanja Trussell

A potential blue-green algal bloom that appeared in Williams Lake on Sunday July 18th has now cleared. The bloom was limited to a stretch of shoreline near the junction of Wyndrock Drive and Litchfield Crescent. A local resident alerted the Williams Lake Conservation Company (WLCC) and contacted the provincial Department of Environment. There was no indication of bloom in other parts of the lake or at the public beach area of Cunard Pond.   

In response to the WLCC posting an alert about the possible bloom on social media, a water specialist from HRM contacted the WLCC and had initially planned to come and collect samples. However, they were subsequently told to pass the investigation on to the provincial authorities as the bloom was outside the HRM beach area.    

The Department of Environment sent an investigator to check the situation on Wednesday, July 21st. The inspector thoroughly checked the area but was unable to take useful samples because the bloom had disappeared by then. Rapid clearance of the bloom is good news, but this does mean we may never know the identity of the causative agent. Not all blooms are caused by blue-green algae, which is a misleading name for these photosynthetic bacteria, which are more accurately termed cyanobacteria. Also, not all cyanobacteria produce toxins, so even some blooms caused by cyanobacteria may be unpleasant but not toxic. For more information You can read more about blue-green algal blooms on the Nova Scotia government environment page.

Local water experts tell us that identifying the microorganism associated with a bloom can be extremely difficult and confirming the presence of toxin, even more so. Blooms can arise quickly and be transient. Rapid growth is fuelled when water temperatures and nutrient levels rise. Water levels in Williams Lake have been decreasing rapidly this summer, the combined effect of lack of rain and the failing dam at the eastern end of the lake. The shallower lake levels may have contributed to the appearance of the bloom, possibly aided by fertilizer run-off from lawns and gardens along the developed portion of the shoreline. Going forward, the WLCC asks homeowners on and near Williams Lake to help protect the water quality by following gardening practices that limit nutrient run-off. For tips on this see Living with lakes: hints for home landscape and garden ().  

Note: “nutrient run-off” in lakeside residential areas is often due to the use of lawn and garden fertilizers near the shoreline.

This incident is a reminder that all users of Nova Scotia lakes need to take care during the hot summer months.  If anyone sees what they suspect to be a blue green algae bloom then they should a) take a picture and b) notify NS’s Inspection Compliance and Enforcement Office by either email  [email protected] or calling their after hour Environmental Emergencies Hotline:   1-800-565-1633 between 16:30 and 08:30 M-F and weekends. If a bloom is suspected in Williams Lake, the WLCC would also like to be informed. We can be contacted via our website’s Contact Us page.  

UPDATE: Potential Blue-green Algal Bloom in Williams lake NS