Foreword
Realising the hard truth that all natural water courses may not be maintained at an uni- formly high level of quality the concept of classification and zoning has been introduced in many industrially advanced countries. In India too, the sooner this concept is introduced in water pollution control management the better gain should be effected in maintaining the quality of natural water courses. The State Boards for the Prevention and Control of Water Pollution have already adopted the concept as a tool for pollution control strategy.

In the present treatise a basis for such a classification is expounded. Examples to illustrate the procedure are also included. Primary Water Quality Criteria for the various classes of fresh water are presented. Criteria for coastal waters will be included in another publication. The Nati- anal Maps incorporating the Zoned Class of the fourteen major rivers will be published shortly. It is believed that the treatise will be found useful by all