Aquatic species and the environment of many rivers in India are under threat. The threat is caused by the disposal of untreated domestic and industrial waste into the rivers. The rivers are being polluted by human activities and the pollution rate is higher than the self-cleaning rate. This has led to both long-term and short-term problems. To protect the water resources, tests are being done to ensure water quality. The tests help balance human and environmental needs and to improve or maintain the water environment. Mathematical formulae and equations are useful to predict the changes...