Thompson Rivers University
Thompson Rivers University

Surface Water


Surface water is water that has accumulated on the surface of the ground.

In many parts of Canada, surface water starts as snow or rainfall in the mountains. The rain or snowmelt runs down into creeks and streams. These in turn drain into rivers, lakes, and sometimes into man-made reservoirs on the ground’s surface. Surface water.

In some areas, surface water moves down into the ground, and then it is called, logically enough, ground water. You can find out more about that under the ground water topic.


The Sources of Surface Water

The Surface Water Dilemma

If you live in an area with lots of mountains and bedrock, you probably get your water from a surface source. This has been the traditional source of water in Canada since humans first arrived.

Surface water has two main advantages:

  1. It’s easy to access (all you need is a bucket).
  2. It’s cheap to develop.

However, these advantages lead to pressure on the water supply. When land is developed, runoff is affected. There is competition about who receives the water and confusion about who is responsible for keeping it clean.

In some areas, governments require water licences or permits, which are meant to ensure that no one takes more than their share of water and that they return the water without major pollutants. Those around you must respect your right to clean water; developers must restrict or monitor their activities to ensure they do not affect it.

In short, surface water can be safe and reliable, but it is also susceptible to natural and human impact, since it is exposed and often unprotected.

Contamination Hazards

Natural Hazards

A commmon example of a natural hazard is aquatic life and its by-products. Surface water can pick up nutrients like nitrogen and phosphorus from agricultural runoff. Add sunlight and you have the ideal environment for aquatic plants and animals to grow.

For example, blue-green algae, common to shallow lakes and dugouts, grows rapidly in warm nutrient-rich water and produces a toxin hazardous to humans, wildlife, and domestic animals.

Wildlife, farm animals, and pets need water and drink it directly from the source. If an animal is sick or has parasites, it is likely that it will contaminate the water as it drinks. Other animals may, in turn, drink the contaminated water and become infected.

The harmful organisms or pathogens left behind in the water can be in the form of bacteria, viruses, or protozoa such as Giardia and Cryptosporidium.

Human Hazards

As water is used for recreation, there is a possibility for contamination by:

  • road runoff
  • gas and oil from outboard engines

In addition, many communities discharge treated municipal waste into surface water, which affects downstream habitation.

Another hazard is runoff from heavy rain which contains hazardous chemicals from:

  • agricultural property (pesticides and fertilizer)
  • industrial property

Almost everything that goes into a storm drain will end up in a stream or lake. Most household or industrial chemicals are not removed by typical municipal treatment.


Possible Sources for Surface Water Contamination

As surface water runs across the surface of the ground and is open to the atmosphere, it can pick up contaminants easily. Surface water should not be used without boiling or treatment.

Campers, hikers, or hunters who drink from a freshwater stream assuming that it is pristine, can get severe stomach cramps and persistent diarrhea that may last for weeks if untreated.

Contaminants can come from human activities such as camping or boating, which can leave gasoline and oil in surface water. Or contaminants can occur naturally as microorganisms, which are harmful to our health.

Surface water can contain many types of biological hazards, and it’s expensive to test for each type. Common tests are for coliforms or E. coli bacteria. The tests are simple, relatively inexpensive, and, if these indicator bacteria are detected, it’s a sign that other hazards may be present.

Chemicals can also contaminate surface water through runoff and upstream discharges.

Construction Tips

Construction Tips for Surface Water Sources


Correct Set-up of Surface Water Intake Pipe


Incorrect Set-up of Surface Water Intake Pipe

  1. Surface water intakes should be placed as deep and as far away from the shoreline as possible.
  2. Lake water naturally separates into layers. The sun warms the top layer, which is the layer used for recreation in the summer, where most runoff accumulates and where most biological activity occurs. At a depth of 9 to 15 metres (30 to 50 feet) there is a dramatic drop in temperature. Water at this lower level usually doesn’t mix with the surface layers, so it is less likely to contain harmful pathogens.
  3. Surface water intakes should be placed a third to half a metre (1 to 2 feet) off the bottom of the source to avoid sediment (dirt).
  4. The mouth of the intake should be fitted with a large, fine-mesh screen. A screen with a large surface area reduces the likelihood of fish or other marine life being sucked into the intake pipe.
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