Benthic macroinvertebrate communities were collected in various streams in agricultural and urban areas in Korea. Community structure and species abundance distribution in benthic macroinvertebrates were comparatively analyzed to reveal ecological states pertaining to the sample sites. Species richness in the total macroinvertebrate communities decreased in the gradient along with increase in the level of pollution. Some selected taxa were present in communities collected in the streams in agricultural areas. The rank-abundance curves were also characteristic in revealing community structure according environmental impact. Patterns of species abundance were efficient in revealing ecological states of the sample sites where physico-chemical indicators may not be easily differentiated in stressful conditions. The feasibility of ecological informatics was further discussed in revealing ecological water quality.