Which water management issue is a concern for Lake Ontario due to urban runoff?

Urban runoff is a significant concern for Lake Ontario primarily because it contributes to water pollution. When rainwater flows over urban surfaces, it picks up various pollutants, including oils, heavy metals, and nutrients, such as nitrogen and phosphorus from fertilizers. This runoff then drains into nearby rivers and streams, eventually leading to the lake.

The introduction of these pollutants can have detrimental effects on water quality, leading to problems such as algal blooms, which can deplete oxygen levels and harm aquatic life. High levels of nutrients can cause eutrophication, reducing the availability of clean water for recreational activities and drinking. Furthermore, contaminated water can pose health risks to both humans and wildlife, making water pollution a pressing issue for the management of Lake Ontario.

While water scarcity, rising temperatures, and invasive species are relevant concerns for many lakes and ecosystems, urban runoff directly correlates with the quality and cleanliness of water in Lake Ontario, which is why pollution is the primary issue highlighted in this context.