Water is a unique substance, because it can naturally renew and cleanse itself, by allowing
pollutants to settle out (through the process of sedimentation) or break down, or by diluting the
pollutants to a point where they are not in harmful concentrations. However, this natural process
takes time, and is difficult when excessive quantities of harmful contaminants are added to the
water. And humans are using more and more materials that are polluting the water sources that
we drink from. In nine of the last ten years, large blue-green algae blooms have appeared on
the northern part of Lake Winnipeg. These are caused by excess phosphorus in the water.
Fertilizer use is 15 times higher today than it was in 1945. Beach closures are becoming
increasingly common. The list of pollutants is long and the signs of water pollution surround us,
but the point is this: we are dumping contaminants into the small portion of water on the planet
that is fit for drinking.