Periphyton, water chemistry, and qualitative habitat data from 44 stream segments in the unglaciated Western Allegheny Plateau ecoregion of southeastern Ohio were collected to determine the interrelationship of physical, chemical and biological data for monitoring impairments. For comparison purposes, an epilithic riffle sample and a multi-habitat sample were collected. A diatom community model using genus level taxonomy was created from 10 reference sites distributed throughout the region. Reference sites had high quality habitat, minimal anthropogenic disturbance, and fulfilled OEPA water chemistry standards. Scores were derived from percent similarity to the model ranging from 0 - 100 with higher percent similarity indicating less impaired conditions. Several chemistry variables were correlated with index scores. Discriminant analysis was used for classifying minimal impairment, moderate impairment, and severe impairment represented by upper quartile, interquartile, and lower quartile scores, respectively. Riffle scores had 92% correct assignations, and multi-habitat scores had 85% correct assignations. The index will be tested on 66 sites sampled during summer 2006. Species models were also used for scoring sites in a similar manner, but require more taxonomic expertise by users. Use of diatom community models shows great promise with ascertaining severity of stream impairment by various stressors.