How Humans Affect the Water Cycle

The Credit River Watershed is part of a larger picture – the greater Toronto bioregion. This region is bounded on the west by the Niagara Escarpment, on the north and the east by the Oak Ridges Moraine and on the south by the north shore of Lake Ontario. Every time humans interrupt the natural water cycle there will be an effect.

We interrupt water pathways in two ways:

1. Withdrawals:

We take water out of the system to irrigate crops, to provide us with drinking water and to carry out many of our industrial processes.

2. Discharges:

We add substances to the water – intentionally or not. As precipitation falls on the ground and moves into rivers and creeks, it picks up a whole range of pollutants. In rural areas these pollutants may include farm pesticides, herbicides and fertilizers as well as wastes from faulty septic systems and improperly handled manure. In urban areas, the pollutants may include gas, oil, pet waste, fertilizers, pesticides, salt and treated human waste from sewage treatment plants.

What we do to this system affects everything within it. For example, what happens if rain that falls from the sky or the water that flows through our streams is contaminated? These contaminants may infect plant or animal life including human beings, or reduce their ability to grow and reproduce. What happens if large quantities of water are diverted or taken out of the system? The reduced flow will likely affect the local water supply but it may eventually change the local environment and alter the plant and animal species that are found here. As we place different stresses on this system, we run the risk of altering or overloading it and causing serious harm.

The Credit River is an important part of the watershed and the water cycle in this area. What we do here affects us locally and eventually affects the health of the water and the communities nearby, including people living in the cities of Brampton, Mississauga, Toronto and others bordering Lake Ontario.