Biologists also play a very important role in the pollution bards of the states. The best possible approach to study the safety of the stream water is by experimental method.
Observation methods will not give true details about such data. Hence, a biologist could collect stream water samples from various points and test them in the laboratory for various parameters. A sample is a representative quantity of the whole content. Since it is practically not possible to test the whole stream water, a sample can be used to perform the experiments and then arrive at the conclusion.