A flow-through, water quality monitoring system, designed to evaluate the spatial heterogeneity of water quality in reservoirs (Grimshaw, 1987), was used to sample Lake Thunderbird, a reservoir near Norman, Oklahoma. Field testing was conducted to evaluate the operational feasibility of monitoring several water quality parameters along multiple transects, in a real-time manner. Results were processed and interpolated using two computer mapping systems and synoptic maps were generated. Qualitative and quantitative comparisons of the two mapping techniques were made. A synoptic map of turbidity, generated from Landsat Multispectral Scanner Band 3 (700–800 nm) data was compared to results obtained from both computer mapping techniques. With the exception of pH and turbidity, the synoptic maps provided similar estimates of lake area within selected intervals, but differed in the degree of detail revealed. Landsat-based turbidity estimates were higher than those measured directly in the littoral zone.