"Water tainted by agricultural runoff is an old concern in rural Canada, but one that is becoming increasingly worrisome as the climate changes. Extreme weather events, such as sudden deluges and floods, increase the flow of pollutants into surface waters. Extended dry periods cause industrial and organic pollutants to build up on the land – then an intense rainstorm can wash it all at once into watersheds. Those storms also cause floods and erosion, which can overwhelm water-filtration systems. At the same time, river flows are declining and water is residing longer in lakes, concentrating pollutants."

Mark Hume reports for the Toronto Globe and Mail April 29, 2014. [2]