This work presents a distributed implementation for processing Maximizing Range Sum (MaxRS) query in Wireless Sensor Networks (WSN). MaxRS query is useful in many spatially-distributed event monitoring and target tracking applications. Given the location and current readings of the nodes, and a rectangle R, MaxRS finds a location of R that maximizes the sum of the readings of all the nodes covered by R. Our system performs MaxRS query in a userspecified time-interval λ and using the result obtained, attempts to maintain a certain degree of energy conservation in the WSN, based on a user-defined threshold δ. Since centralized processing of the raw readings and subsequently determining the MaxRS may incur significant communication overheads, we developed a distributed algorithm to compute MaxRS. We implemented our system in a heterogeneous WSN consisting of TelosB and SunSPOT motes, and illustrate the end-user tools: GUI for specifying required parameters, and real-time visualization of MaxRS solutions and estimated network energy consumption.