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may group into . differing levels of degradation. Future studies need to ascertain if this is true. The results also suggest that chironomid subfamily groupings may have merit in IBI development. Faunal regions for benthic macroinvertebrate taxa indicate an elevational gradient in two groups of taxa. They also represent, to some extent, variation in their tolerance to environmental degradation. Future analyses should explore the utility of urging data for benthic macromvertebrate taxa with data for chironomid subfamilies. The results for fish presence/absence data indicate three fish faunal regions in the upper Rio Grande drainage. These fish faunal regions appear to have some degree of drainage specificity that is caused by the presence or absence of a few key species. Site groupings with relative abundance data for fish suggest two things. First, relative abundance data may have utility. for identifying acceptable versus unacceptable sites with respect to criterion related to desired abundance of certain species. Second, relative abundance data may be useful in identifying reference sites for use with an IBI. Several analyses would provide a clearer understanding of how to proceed with development of IBI's. Future analyses of fish data should determine if fish faunal regions identified on a coarser taxonomic basic, e.g., trophic guilds and/or reproductive guilds, are more consistent with ecoregions obtained with environmental data. Use of alternative taxonomic schemes would accommodate Regier's (1993) observation that "normal and good" doesn't necessarily mean pristine and undisturbed. Alternative taxonomic schemes may also provide an effective means to handle variation between drainages that lie in the same aquatic ecoregion. Similarly, future analyses should determine if a coarser taxonomic classification for chironomids would yield greater similarity with faunal regions obtained with fish species data. In northern New Mexico, our a priori expectation was that there would be a close parallel between -fish distribution and- clvronomid distribution. A cold-water fish fauna dominated by salmonids and selected cypriniforms was expected to be accompanied by a chironomid fauna dominated by diamesine and orthocladine species. However, the present analyses have failed to demonstrate significant similarity between fish and chironomid faunal regions. The differences between fish and chironomid faunal regions lie at different landscape scales, i.e., the high proportion of unique chironomid species per site (about 25 %) confers a high degree of specificity to individual reaches within a stream for chironomid faunal regions. In contrast, the presence of a few introduced species confers some specificity to drainages in fish faunal regions. Similarity of Faunal Regions and Aquatic Ecoregions In general, classifications of sites by cluster analysis on chironomid data have little resemblance to the aquatic ecoregions defined by analysis of environmental variables. This could indicate that an IBI based solely on chironomid species may not be feasible for the upper Rio Grande. The faunal regions obtained using fish presence/absence data had some similarity to the aquatic ecoregions. However, the fish faunal regions also had some degree of