Drone-Based Water Quality Monitoring of a Small Urban Lake: Case of Swan Lake in the Greater Toronto Area, Canada

Urban lakes face increasing pressure from land-use change, urban growth, and climate change, resulting in immediate and long-term social and environmental impacts. Advances in drone technology and payloads have revolutionized environmental monitoring, particularly water quality assessment, by enabling high-resolution, on-demand, and rapid sensing. Recent studies highlight the advantages and complementary role of drone-based monitoring. Swan Lake in the city of Markham in the Greater Toronto Area ( Ontario, Canada), has been monitored for water quality issues caused by high levels of phosphorus, nitrogen, and chloride, which promote algal blooms and ecological decline. A drone with a multispectral camera was used to collect data from May to November 2025. This data was analyzed to calculate water quality indices like NDCI, NDTI, and NDWI, along with relevant statistics. The results reveal detailed spatiotemporal patterns of these indices, supporting more targeted and timely water-quality improvement interventions. This study included a direct comparison of drone-based observations and satellite data to evaluate their relative spatial detail and ability to capture patterns, distributions, and changes over time and space.