Silting within all man-made reservoirs can be a major problem because of a lower potential water storage. Exploring a lake’s bathymetry with electromagnetic techniques is one way to identify the magnitude of sediment accumulation in these reservoirs. In this study, the bathymetry and sediment accumulation of Walker Lake, Pennsylvaia were explored with ground penetrating radar (GPR) using either a 400 or 100 MHz antenna, depending on the depth of the lake. The assembled apparatus herein included two GPR antennas placed in an inflatable boat towed by another boat powered by an electrical trolling motor. A total of eighteen crossings were performed along the entire length of the lake and a new integrated method using multiple processing software was applied to generate three-dimensional and contoured surfaces of bathymetry, sediment accumulation, and the original 1971 basin topography prior to the construction of Walker Lake Dam. The bathymetry, volume of sediment, and its accumulation rate were estimated. The lake depth was found to vary between a few centimeters near the inlet to 9 m nearer the dam. Deposition of sediment takes place mainly near the inlet to the lake and along the old channel of Middle Creek. The sedimentation gradually decreases toward the dam, ranging between 0 and 1.85 m in terms of bulk sediment volume.