The contamination of ground and surface water is primarily a result of human activity. Industry, agriculture, urban development, and even the way we care for the land at our home can affect water quality. Therefore, it is important to have an understanding of how human activities can both directly and indirectly, negatively affect water quality, and in turn threaten drinking water.

Human Activities in the Watershed

It is important to note that a number of natural elements, such as arsenic, mercury and lead, radioactive compounds such as radium and microorganisms such as parasites, bacteria and algae are naturally present in water in small amounts. At low natural levels the presence of these elements, compounds and microorganisms are not a concern. However, when the levels of these elements increase as a result of human activities, they then have the potential to be harmful.

There are two types of surface water and groundwater contamination - point source pollution and non-point source pollution.

Adapted from Pollution Probe's Source Water Protection Primer

Point Source Pollution. Source: Jay MorrissonPoint source pollution enters the environment at a specific place from an identifiable source. Examples are:

• industrial point discharges, as well as spills and leaks of industrial chemicals;
• municipal wastewater effluents;
• landfill site leachate;
• wastes from existing and abandoned mining sites;
• on-site septic systems; and
• leaking underground oil and gas storage tanks.

Corn Field, Quebec. Source: Coreyu, http://www.flickr.com/photos/coreyu/If not properly managed, agricultural activities can contaminate both surface water and groundwater sources. Grazing animals trample shoreline vegetation which increases runoff and decreases soil absorption, animals also can also excrete directly into the water source. Field ploughing can increase soil erosion and runoff, and fertilizer application, pesticide spraying, irrigation and animal faecal matter are all potential direct sources of agricultural pollution.

Wastewater from agricultural activities may contain a number of polluting ingredients:

• Animal wastes in liquid and solid form. Animal waste is not only a strong source of nutrients; it can contain parasites, bacteria, antibiotics and synthetic hormones.
• Silage (grass semi-fermented to be used as winter feed for cattle and sheep) liquor is the liquid produced during the fermentation process in the production of silage. Silage liquid is a pollutant due to its high organic content and acidic pH.
• Pesticides, insecticides and chemical fertilisers may runoff land into receiving waters, especially if they have been applied excessively.
• Milking parlour wastes include milk, animal wash water, animal wastes and cleaning products. The organic waste increases the nutrient content of a water body, which can result in eutrophication. Cleaning products may contain toxic chemicals that can be fatal to aquatic wildlife if they are not removed during treatment.
• Slaughtering waste is animal blood, waste, and cleaning products. Slaughtering waste can have the same effect as milk parlour wastes if not properly treated.
• Vegetable washing water contains small amounts of pesticides, vegetable pieces and soil.

Tainted Water. Source: Joy MundaneMany maufacturing industries also generate polluted waste waters which can pose a threat to drinking water sources if not properly managed. Improper storage and release of chemicals on commercial and industrial sites can have severe adverse impacts on water quality. To protect water sources, wastewater must be properly treated before they are discharged to watercourses. Industrial effluent is strongly regulated, and strict limits are set for the level of contaminants contained in industry wastewater.

While many industrial plants maintain their own waste water treatment systems to ensure their effluent meets regulation standards before being released to a water source, the reduced amount of pollution found in treated industrial effluent can still be a concern.

Adapted from Pollution Probe's Source Water Protection Primer

City Streets. Source: CaribbThe expanding human population is a major source of environmental degradation when it exceeds the capacity of the environment to support it. Population increases impact the environment primarily through the increased use of natural resources and production of wastes. This is creates environmental stresses like loss of biodiversity, air and water pollution and increased pressure on land.

The pressures on surface water and groudwater sources are brought by agricultural activities, industrial activities and urban development.

Private wells provide important sources of drinking water for rural homes, but in order to continue providing fresh clean water they must be properly maintained and kept free of contamination. In order to prevent illness, wells should be regularly tested for the presence of bacteria and chemical contaminants. It is recommended to test for bacteria at least three times a year and to test for chemical contaminants at least once a year.

Wells

   Adapted from Health Canada: A guide to well water treatment and maintenance