How Much Water Do We Have ?

Part 2 from Rideau Valley Conservation Authority

Eastern Ontario is blessed with a sufficient quantity of good quality water to do most everything we want to do … it is a liquid legacy that is the envy of the world.   While we sometimes experience local gaps in supply or quality at certain times of the year or as a result of particular man-made events, we generally have plenty of water for our needs. However, with our abundant water comes a responsibility not to waste it so we can ensure there is enough for fish, wildlife, instream needs and for future generations.

How much water we get and where it goes in the watershed is known as the water budget.  In our area, we have traditionally received an average of 912 mm of water a year as rain and snow.  An astonishing 547 mm of that (60%) is very quickly lost back to the atmosphere either through evaporation or humidity after being used by plants.  That leaves 40% or about 365 mm to flow through the valley as lakes, streams and groundwater to be used by animals and people in various ways.

Wetlands: About 13% of the Rideau and Mississippi watersheds are covered by marshes, swamps, bogs and fens.  These wetlands provide many valuable ecological services to the people of the valley such as flood reduction, wildlife habitat, erosion protection, water cleansing and groundwater recharge. 

Lakes/Rivers/Streams: The beautiful surface waters of the Mississippi and Rideau valleys provide other valuable products and services for people.  These include residential sites, recreation of many kinds, fish and wildlife and a lot of peace and quiet.  Surface water made up of lakes, rivers and streams is estimated to cover about 7% of the local land mass.  Combined with the estimated 13% covered by wetlands means about 20% of our region is water!  This is much greater than most other areas of the world.

Groundwater: Only 10% of our rain and snow makes its way down through the soil to replenish our underground water sources (aquifers).  In the Mississippi and Rideau watersheds, groundwater is critical to the nearly 140,000 people who rely entirely on wells for their daily potable water.  Fortunately, scientists tell us that there is much more water underground than we see on the surface.  While there seems to be plenty of local groundwater, we can experience periodic shortages due to seasonal or man-made fluctuations. 

Drinking water: Drinking water use (both from municipal systems and private wells) accounts for less than 1% of the total amount of water available in our area.  Agriculture and industry use even less than that.

In the end, our demand is fairly low in relation to the amount of water available in Eastern Ontario.  Supply however can vary from day to day, month to month and year to year depending on weather, climate, land cover and human uses or abuses.  Canadians are among the heaviest water users in the world with each of us using 300+ litres of water each day! Even in our region it is good practice to use water wisely so we can keep our supply and demand balanced for years to come.  This balance is critical for the health and well-being of our watershed residents.

Next topic:      Who protects our water supplies?
 

 
For more information:            Sommer Casgrain-Robertson
                                               Co-Project Manager
                                               Mississippi-Rideau Source Protection Region
                                               1-800-267-3504 or 613-692-3571 ext 1147
                                               sommer.robertson@mrsourcewater.ca