Using macroinvertebrate data to assess water quality is a common tool nationwide, with varying levels of emphasis placed on the efficacy of sorting invertebrates from collected samples. It is believed that separation of all organisms from detrital matter is important in evaluating many commonly used metrics. Unfortunately, the task of sorting samples tends to fall on inexperienced staff. Sorting efficiency is reduced when inexperienced personnel are constantly rotated in, which could lead to artificial temporal and/or spatial errors on long-term projects. The objective of this study was to determine if sorting error significantly impacts the resulting data for a variety of metrics commonly used in biomonitoring programs. ES&C provides extensive training to new employees and collects sorting QA/QC data randomly for 10% of all samples processed. Additionally, every sample sorted by new employees is resorted during training until the sorter reaches better than 90% accuracy. A sample is deemed to have failed QC if sorting accuracy falls below 90%. Training and QC data were taken from approximately 62 different sorters between 2002 and 2006. Metric results were calculated before and after each sort QC, and compared. The results of this study will be discussed in the presentation.