Assessment of water quality of a pond ecosystem using biological water quality criteria

The present study evaluated the water quality of Dighali Pukhuri, a freshwater pond ecosystem in Guwahati city, using Biological Water Quality Criteria (BWQC). The study determined water quality class of the sampling site taking into accounts of both Saprobic score and diversity score of aquatic insects using BWQC. Sampling was done in monsoon, post-monsoon, winter and pre-monsoon seasons during the year 2010–11 and 2011–12. Results of the study were compared with BWQC to assign different classes to the study site. The most prevalent biological water quality Class was “B” (slight pollution) which accounted for about 65.5% of the total classes present. It was followed by Class “C” (moderate pollution) which accounted for 25% of the total biological water quality classes. The Class “A” (clean) contributed only 12.5%. The prevalence percentage of different biological classes can be shown as Class “B” > Class “C” > Class “A”.