Pesticides are sprayed aerially on crops and water to protect them from pests that chew up the crops and contaminate the water. However, the aerial spraying also causes chemicals used in the pesticides to spread in the atmosphere and water bodies thus contaminating the environment (G. Chesters and J.G. Konrad).
Spraying of pesticides temperature-specific and there are certain conditions when they must be done. Ideally, pesticides are sprayed when there are little or no wind and when a temperature inversion exists between 3 and 10 meters above the ground. The lack of wind movement prevents the pesticides from spreading around. However, such conditions rarely exist and pesticides are spread around inside and beyond the region pesticides are sprayed (G. Chesters and J.G. Konrad).
Lake Erie is affected by "five most heavily applied agricultural pesticides. They are metolachlor, atrazine, cyanazine, acetochlor and alachlor." The lake water has heavy concentration of these chemicals.