In a balanced study of water pollution or water utilization a thorough chemical and physical examination is essential. This provides a basis for evaluation of stream conditions, their effects and remedies. Such information is of value to the general public who are interested in clean water and in recreation, hunting, fishing, and wildlife; to the chemist, engineer, hydrologist, and industrialist who are interested in the domestic and industrial use of water both as raw material and as a vehicle for the removal of waste materials; to the sanitarian who is interested in healthful conditions; and to the biologist who is interested in maintaining a favorable biological balance. For every living plant and animal there are optimum physical and chemical conditions and these characteristics are determining factors in the aquatic life of any body of water.