Soluble nutrients, mainly nitrogen, can reach ground water through soil can result in significant problems in areas where high rates of nitrogen fertilization are used, where soils are highly permeable, where there is wide use of irrigation or where ground water levels are near the surface. By their nature, pesticides and herbicides are toxic substances. Many are highly toxic to fish, other aquatic organisms and warm blooded animals. Soluble pesticides and herbicides can reach ground water, rendering it unsafe for drinking or necessitating expensive cleanup. Pesticide leaching is more critical in areas where high amounts or pesticides are used, where soils are highly permeable, where there is widespread use of irrigation or where ground water levels are near the surface.
Some pesticides persist in the aquatic environment for long periods of time.
Even at very low concentrations. Animal waste and crop debris are the major organic pollutants resulting from agricultural activities. During decomposition, they place an oxygen demand on recieving waters which can result in stress or death amoung fish and other aquatic species. When water is contaminated by animal problems can occur. These include diseases such as infectious hepatitis, typhoid fever, dysentery and other forms of diarrhea.