Shallow seismic reflections were used to map the bedrock under dry alluvium near a pond in Texas. This helped place water-quality monitor wells accurately. The data showed shallow bedrock valleys and varied velocities in the alluvium. Monitor wells drilled in the area went through unsaturated alluvial material. The seismic data had a dominant frequency of 170 Hz, and filtering improved the bedrock reflection. The final map combining drilling and seismic data showed a detailed bedrock contour, revealing a hidden bedrock valley that drilling alone couldn't detect.