Foreword
The maintenance of quality of river hinges around the under- standing of the magnitude of potentia;l pollutants that could travel and reach the river to threaten the aquatic eco-system. A pollutant sinking at a river stretch, may not be final resting place, but it could pr;)ve potential source for another stretch and another pollutant. How and where, in what form and in what concentration pollutants are locally and spatially distributed in times, may be an index of our control strategy.

To carry out the above mission the Central Pollution Control Board comp!eted the desired prerequisite of the identification of the polluting soyrces, their magnItude and spread river basinwise. A formal pub!ication 0( the Central Board under ADSORBS/2/1980-81, The Ganga Basin Part I, Tbe Yamuna Sub-Basin, presented treatise on magnitude and sources oi the various pollutional loads, taking all sorts of anthro- pogenic activjties jn

consideration, upto the period 1976-77. This river basin inventory programme continued to date. This short publi- cation reviews the above programme for River Yamuna and presents the observed trend in its water quality for the period 1977-'1982. , This publication may 'be used as a model to review the other long-term rIver pollution assessment programmes in the country.

The supervision of Dr. R.H. Siddiqi in the interpretation of data is gratefully acknowledged. Mrs. Usha Ghosh, Assistant Statistical Officer, coordinated the interpretation of all water quality parameters except heavy metals, the interpretation of which was coordinated by Dr.(Mrs.) K.K. Saxena, Scientist. Both assisted Dr. ,Siddiqi in the preparation of the report. Shri Ani1 Kumar and Shri Arun Kumar Sinha, Apprentice Scientists of the Statistics Section compiled and tabulated the data. ' The manuscript is carefully typed by Shri Ashok Kashyap and tracings and drawings are prepared by Mrs. Bonya Basu and Shri K.K. Gupta. .