Benthic macroinvertebrates communities were collected at more than 1,700 sites in the wadeable streams and rivers in 12 states of the western U.S. (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming) in the program of the Environmental Monitoring and Assessment Program (EMAP) Western Pilot (EMAP-W). The eventual objective of EMAP-W is to assess the ecological condition of, and relative importance of, stressors in streams and rivers of the West at multiple scales. In the dataset, totally 617 species were identified. Metrics were developed from the benthic macroinvertebrate communities, and 103 variables were identified by considering species richness and relative abundance of different taxonomic groups, functional groups, habitat types, different tolerance levels, etc. We compared relations between different categories of metrics components through computational methods including artificial neural networks and statistical multivariate analyses