Abstract: Lake is a region with water bordered by land. Lake is more contrasted to river. The main difference between rivers and lakes is the movement of water, in river the water moves along its, but the lakes are surround by the land. In maintaining ecological balance lakes play an important role in urban areas the water from the lake is used for many purposes and also for irrigation. Muttukadu Lake is a famous lake located on the east coast road (ECR) at muttukadu. In this work deals with the detection of water quality index value based upon Weighted Arithmetic key method by examining various characteristics such as pH value, conductivity of electricity data, Total stiffness value, amount of magnesium content and calcium contents, Total solids dissolved in water etc to analyze the quality level of water all the purposes. Here in this implemented paper the samples from the Muttakdu lake is collected and the parameters and checked with the collected samples.