Algal bloom advisory issued for Calgary’s Lake Sundance

Alberta Health Services has issued a health advisory for Lake Sundance, a private community lake in Calgary’s southeast, due to the presence of cyanobacterial (blue-green algal) blooms. The advisory was released on August 14, 2026, after tests confirmed the presence of toxins produced by the algae. Residents and visitors are urged to exercise caution while using the lake, as exposure to the blooms can pose health risks. The algal bloom, which has taken on a greenish-brown appearance, has been observed in parts of the lake. According to AHS, cyanobacteria are naturally occurring organisms that thrive under specific conditions, such as warm temperatures and high nutrient levels. Scientists note that these blooms are becoming more frequent due to prolonged summer seasons and rising temperatures. Dr. Marc Strous, a researcher at the University of Calgary, explained that the combination of heat and available nutrients creates an environment conducive to rapid algal growth. Lake Sundance is accessible solely to residents of the Sundance neighborhood. While the lake remains open for recreational activities, strict guidelines have been established to minimize risk. Visitors are advised not to swim or wade in areas where blooms are visible. Contact with the algae, whether in water or on shore, should be avoided. If contact occurs, individuals should wash with clean tap water immediately. Drinking or cooking with water from the lake is prohibited, and consumption of whole fish or fish trimmings is discouraged due to potential toxin accumulation in the liver. Fillet portions are considered safer. Pets must also be kept away from affected areas, and feeding them fish from the lake is not recommended. Symptoms associated with exposure to cyanobacterial blooms include skin irritation, rashes, sore throats, red eyes, swollen lips, fever, nausea, and diarrhea. These effects typically manifest within one to three hours after contact and generally subside within one or two days. Children are particularly vulnerable, often experiencing more severe symptoms than adults. Dr. Strous emphasized that eliminating the blooms through treatment is challenging. He noted that the algae will likely diminish as temperatures drop and daylight decreases, leading to reduced sunlight and slower bacterial activity. Recent cloudy and cooler weather in Calgary has contributed to a reduction in bloom intensity. However, ongoing monitoring is necessary to ensure public safety. The advisory highlights the growing concern around cyanobacterial blooms in freshwater bodies across Alberta. Environmental scientists warn that climate change is exacerbating the problem, making such advisories increasingly common. Public awareness and adherence to safety measures remain critical in preventing illness related to algal exposure. As the situation develops, local authorities continue to monitor the lake and provide updates to the community. Further action may be required depending on how the blooms evolve and respond to environmental changes. For now, the focus remains on educating residents and ensuring compliance with the precautionary guidelines outlined by Alberta Health Services.