Material From Original Gov't Discussion Paper
[ Intro to groundwater nitrates concern from original discussion papersource#1, "Commopn Concerns" section p. 1-2 ]Nitrates are chemicals made up of nitrogen and oxygen. They occur naturally and are essential for plant growth. However, excess levels of nitrates in soil increase the risk of contamination to water supplies, creating a potential health concern.
Improper application of manure or commercial fertilizers to fields can cause nitrates to build up in soil. Seepage from manure storage areas, or from domestic septic fields and municipal sewage systems, may also cause excess nitrate levels.
If nitrates leach from the soil into underground aquifers, well water can be contaminated. The extent of contamination, and how quickly it occurs, depends on soil type and depth of the water source. Nitrate contamination is more common in shallow wells than in wells drilled into deeper aquifers. Heavy rains and flooding also affect the amount of nitrate that reaches both ground and surface water.
Nitrate in drinking water can be a health concern because it interferes with the ability of red blood cells to carry oxygen. The shortage of oxygen may affect infants or the fetus in pregnant women.
The recommended limit for nitrate in Manitoba drinking water is 10 milligrams per liter (nitrate measured as nitrogen). This is the same limit established by Health Canada, as well as by the U.S. Environmental Protection Agency and the World Health Organization.
In Manitoba, the Livestock Manure and Mortalities Management Regulation sets maximum levels of nitrate that may be present in soils. These limits match the annual nitrogen requirements of the crop to be grown. In this way, the restrictions are intended to prevent a build-up of nitrates in the soil and minimize the risks to groundwater.
Large-scale operations are required to register annual manure management plans, including mandatory soil analyses and descriptions of soil conditions, crops to be grown, quantity and nitrogen content of manure to be applied and locations where manure is to be applied. (For further detail, see "Manitoba Regulations and Guidelines.")
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Material From "Common Ground" Government Report
Other Material and References