GREELY, Ont. – Well water in Greely has become more toxic, according to a city study, and it’s a problem the city’s been aware of for at least five years.

Metro reports the problem is nitrates in the city-operated Shadow Ridge well system.

A drinking water management report shows levels of nitrates in the well water rose by more than 27 per cent in 2016.

High nitrate levels can cause “blue baby syndrome,” where babies turn blue from lack of oxygen. It has the potential to be fatal.

While nitrate levels have varied widely between tests, all results have been below the threshold at which the water is considered dangerous to drink.

At least one engineering firm concludes that nitrate levels are declining as agriculture dwindles around Greely.