Using Lake Ontario to cool Toronto

The Globe and Mail [theglobeandmail.com] The water's cold will be extracted and used to lower the temperature in downtown buildings. The water will then be treated and enter the city's drinking supply.

From the Department of Why-Hasn't-Anyone-Thought-Of-This-Before, comes the idea of using near-freezing water from the depths of Lake Ontario to use as the cooling agent for air-conditioning in Toronto's office buildings.

Here's a site that explains how it works.

Basically, super cool water from Lake Ontario is pumped to a heat exchanger before entering Toronto's water supply system. The cold extracted from the heat exchanger is then pumped via water pipes to Toronto's buildings, and is used to cool the buildings' cooling systems via another heat exchanger.

Posters on Slashdot, known haven for geeks, then wondered if this heat exchange process would -- in obeying the laws of thermodynamics -- cause the temperature of the lake to rise, causing other unforeseen environmental effects.

I think it would not, since the water would be going through the water supply system anyway, the heat gain (cold loss?) probably would have occurred anyway, in the form of waste.