Question

Potter's Lake used to be the nicest lake in the area. But these days the water is green with algae, and the lake is choked with weeds all summer long. As a result, people can no longer swim in it. Experts have determined the cause of the problem.Fertilizers from yards and farms have been running into the lake. They cause algae and weeds to grow out of control. They also kill birds and fish.

Answer 1

Use less fertilizers, or something that won't harm the environment. 
(Build on that)