Sample Response: The increase in algae could be related to Sarah’s farm due to her use of fertilizer. Fertilizers help produce strong, healthy crops, but they can also wash into lakes and rivers. When they do, they provide a large food supply for the algae living there, which can cause the algae population to increase dramatically. Samples from the neighborhood lake show high levels of phosphorus and nitrogen, the key ingredients of most fertilizers, and a large increase in the algae population. It is therefore likely that the lake contains some of the fertilizer from Sarah’s farm.
