Huge amounts of chemicals, such as fertilizers and pesticides, are applied to farm fields (see Figure below ). Some of the chemicals are picked up by rainwater. Runoff then carries the chemicals to nearby rivers or lakes. Dissolved fertilizer causes too much growth of water plants and algae. This can lead to dead zones where nothing can live in lakes and at the mouths of rivers. Some of the chemicals can infiltrate into groundwater. The contaminated water comes up in water wells. If people drink the polluted water, they may get sick.
Farm A and Farm B use different methods of controlling pests on their crops. Farm A uses fertilizers and pesticides on their crops. Farm B is organic and does not use fertilizers or pesticides.
Will the lakes and rivers near Farm A have more or less water plants and algae than Farm B?