Foreword
Lakes and ponds are important surface water resources, which facilitate harvesting and storage of rainwater through their catchment areas and replenishment of the ground water. Due to increasing anthropogenic influences and extensive urbanization, several of such water bodies within the urban city limits are gradually being diminished or transformed into the marshes and shallow depressions.

The environmental health of aquatic ecosystems can be determineQ by measurement of certain chemical parameters. However, the biological effects of environmental changes are comprehensively ass"essed through bio:.monitoring of water bodies. In order to assess the existing status of water qualjty in various surface water bodies viz. lakes, tanksre servoirs within densely populated habitations, the Central Pollution Control Board has undertaken water quality studies in urban areas of Delhi. In present