by Suzanne Goldenberg
August 3, 2014
The toxins that contaminated the water supply of the city of Toledo – leaving 400,000 people without access to safe drinking water for two days – were produced by a massive algae boom. But this is not a natural disaster.
Water problems in the Great Lakes – the world’s largest freshwater system – have spiked in the last three years, largely because of agricultural pollution. Toledo draws its drinking water from Lake Erie.
Scientists attribute the comeback in large part to changes in farming practices, including larger farms and different fertiliser practices, which send heavier loads of phosphorus into the lakes.
Lake Erie has also grown more susceptible to the algal blooms because of invasive species and climate change. Heavy rains in spring and early summer – a critical time for algal bloom formation – cause more phosphorus to enter the lake through agricultural runoff. Hotter temperatures then cause the blooms to spread.