The objective of the study was to develop a Eutrophication Index to evaluate the trophic status of the lake system. A database was formed from several studies, and using the Pearson correlation coefficient, the five most influencing parameters were selected. These comprised of total phosphorus, total nitrogen, chlorophyll-a, biochemical oxygen demand, and Secchi depth. Delphi technique was adopted for weightage assignment and plotting of rating curves, according to which total phosphorus was the most influencing and Secchi depth was the least influencing parameter. Twelve different functions were taken into consideration for parameter aggregation, out of which seven functions were screened off based on non-accountability of weights, ambiguity, and eclipsing issues. For the remaining five functions, a sensitivity analysis was carried out. It was inferred from the results that the weighted arithmetic mean function was the most suitable aggregation function for the developed eutrophication index. A comparative analysis was done to check the accuracy of the developed index and it was found that the index gave good results.