In contrast to existing trends and expected deteriorating water quality in the river Yamuna in Delhi which carries potential cultural economical and health importance, March 2016 water data showing improvement despite large public gathering at river bank during Cultural Festival. The reasons and factors were investigated. The paper presents the test reports of eco- enzyme which was found to be used during the event of World Culture Festival at the river bank in March 2016. The eco- enzyme is found to positively affect pH (from 6.7 to 7.2) reducing solids (from 884 to 745) suspended solids-(from 121 to 47) hardness and chlorides in a stable water body- Pond. The eco- enzyme testing in drain water showed optimum water cleaning effect on 0.5% concentration by showing the reduction of Biological Oxygen Demand from 690 to 231, Chemical oxygen demand from 537 to 384, nitrates (from 5.54 to 3.39) Coliform count by 10%. Considering cost-effectiveness of the enzyme it is considered feasible technique to mitigate polluted water bodies.