Two Autonomous Underwater Multi-Dimensional Acoustic Recorders (AUMDAR) were deployed in the southeastern part of Lake Travis during the summer of 2018. Each AUMDAR system possessed a three-axis acoustic vector sensor capable of estimating the azimuthal and vertical arrival angles from discrete sound sources. A unique and complicated propagation environment existed during the experiment due to the mooring locations and the range-dependent lake bathymetry. The AUMDAR systems were almost entirely shielded from sound emanating from surface vessels to the south and southeast of the deployment location, while a larger, yet limited, direct acoustical field of view was realized to the north and northeast. During the evening hours, the low-frequency received level increased without a corresponding increase in the number of detected discrete surface vessels. During the same time, the predominant direction of the received sound pointed toward the bend in the river channel. A three-dimensional ray model was employed to assess the various arrival angles from a grid of source positions located throughout the lake. The model results are consistent with the observations and suggest that the ambient noise field originated from vessels physically located to the northwest of the sensors, but arriving at angles consistent with out-of-plane sound propagation.