| | Agriculture and water quality
The United States Environmental Protection Agency (USEPA) ranks agricultural activities as the most significant cause of impaired water quality in streams and lakes (Cohen and Mallard 1993; Daniel et al. 1994). Studies indicate that agricultural activities can impact both surface and ground water. For instance, long-term tributary monitoring programs in the Lake Erie basin clearly document agricultural impacts (e.g. high nutrient loads) on the water resources of that region (Logan 1982; Baker 1993). Furthermore, Moody (1990) found excessive applications of animal manure and agricultural chemicals on cropland to deteriorate ground water quality in intensively farmed areas of Pennsylvania. Research throughout North America suggests that agricultural practices can deteriorate surface and ground water quality resulting in significant public health and environmental impacts.
Agricultural production can generate contaminants that can have many negative effects on surface or ground water supplies. Contaminants that are associated with cropping and livestock practices include sediment, nutrients (nitrogen and phosphorus) from inorganic fertilizers and organic livestock wastes, crop protection chemicals such as herbicides and insecticides, microorganisms from livestock wastes, and salts and trace elements from irrigation residues. Contaminants are transported, either attached to sediment or dissolved in water, to surface and ground water through all phases of the water or hydrologic cycle. Impaired water quality can restrict water uses for such activities as stockwatering and irrigation, drinking water supplies, sport fisheries and other aquatic life, and recreation. In summary, agricultural activities, in addition to other land uses, can have a significant impact on the quality and uses of our water resources. |
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