System performance measurement often is conducted using subjective methods, such as self-reporting of utilization, or surrogate measures, such as user satisfaction. High system utilization or high user satisfaction provides no guarantee of high performance. This study reports initial research relating system utilization, measured as a continuous and independent variable, with an objective measure of system performance. The usage or participation rate of the New Orleans Vessel Traffic Service was correlated with its performance criterion of vessel safety, operationalized as the number of marine accidents. The evaluation model reported in this research employed utilization as an independent variable in the regression equation. This utilization measure was inversely correlated with vessel accidents -- increases in DSS utilization were associated with reductions in marine casualties, assuming fixed levels of the other explanatory variables. This research has provided evidence that the system has been very effective in reducing vessel accidents -- the objective performance criterion -- on the lower Mississippi River. IS managers should consider this method of evaluation as a means of increasing information management credibility.