This document describes an investigation of the effect of survey technology and accuracy and reliability of hydraulic roughness estimates on the accuracy of computed water surface profiles. The survey technologies studied include field surveys, aerial surveys, and topographic maps as data sources for stream cross-sectional geometry. A Monte Carlo simulation strategy was applied to develop an array of computed profile errors for the survey technologies and selected accuracies, and Manning's coefficient reliability. Regression equations were derived for predicting profile errors as a function of survey technology, selected accuracy, Manning's roughness coefficient, and stream hydraulic properties.