The primary purpose of this report is to present information on the impacts of agriculture on water quality from a North American perspective. Information from this report will be developed into awareness materials for producers about potential agricultural impacts on water quality. Pollutants can harm the natural biological and chemical processes in aquatic ecosystems. Therefore, by understanding these natural processes, the cause of aquatic pollution can be linked to the effects. Furthermore, the understanding of how contaminants are transported to lakes and rivers is essential in designing and implementing land management practices to reduce pollutant loading to surface and ground waters.
Aquatic ecosystems are dynamic natural systems that respond to change, either manmade or natural.
Although many Alberta lakes are naturally eutrophic from lying on top of naturally fertile soils derived from sedimentary bedrock, their productivity has likely increased from increased land development in the surrounding watersheds. High inputs of plant nutrients, such as nitrogen and phosphorus, from chemical fertilizers or livestock wastes can accelerate the eutrophication of surface waters causing lakes and rivers to experience large algal blooms and excessive aquatic weed growth. These conditions are aesthetically unpleasant, prevent recreational activities such as boating and swimming, and limit the use of water supplies for drinking purposes. In addition to inputs from the watershed, lake sediments are also a significant source of phosphorus to prairie lakes. For some prairie lakes, the lag time between increased phosphorus loads and increased algal growth and other aquatic plants may be decades.