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The second cluster, the Chama River below Abiquiu Reservoir and the Jemez River above the confluence with the Guadalupe River, represented sites having a possible low to moderate level of degradation. The mean number of species per site was 29 and the mean number of unique species per site was 8. The third cluster grouped all three of the sites on the Costilla River system. These sites; • probably. -with • a-• moderate - to high level of degradation, had a mean of 25 chironomid species per site, but, the mean number of unique species per site was only 2. The fourth cluster contained three sites on the Chama River, two of which are downstream from reservoirs, with a high diversity of chironomid species (mean number of species per site=41). However, the mean number of unique species per site was only 4. The high species diversity coupled with a relatively low mean number of unique species may be indicative of reservoir tailwater influence on species composition. The tree branch labeled 5 on the cluster tree (Figure 8) represented an outlier site with respect to the other sites in the upper Rio Grande drainage. That site, on the Chama River above the town of Chama, had 76 species of chironomids, 22 unique species, 31 species represented by only one specimen, and 53 species represented by 5 or fewer specimens. quality, chironomid data, especially species diversity and rarity, may be prove useful in development of an IBI. Benthic Macroinvenebywe Taxa Faunal Regions Data for benthic macroinvertebrate taxa were available at 30 upper Rio Grande sites (Table 3). All 30 sites also had environmental data available. Thirty of the 31 upper Rio Grande drainage sites sampled for benthic macroinvertebrates (including Chironomidae as only one taxon) contained 126 taxa (Table 3). Four groupings of sites were obtained with cluster analysis of presence/absence data (Figure 9). Cluster 1 included high elevation sites in the Jemez River drainage and the Chamita River. These sites had a mean elevation of 7915 ft and a range of 7500-8400 ft. The second cluster included low to middle elevation sites in the Jemez River, middle elevation sites Chama River drainage, Red River and Rio Pueblo. Cluster 2 sites had a mean elevation of 6242• ft and a range of 5660-7290 ft (excluding the high elevation outlier site Polvadera Creek). Cluster 3 sites, with a mean elevation of 6116 ft and range 5410-6700 ft, were lower Chama River and mainstream Rio Grande sites. Clusters 1 and 4 represent Aquatic Ecoregion 1 and clusters 2 and 3 represent Aquatic Ecoregion 2. Cluster analysis of chironomid Taxonomic diversity appeared to be higher presence/absence data does not seem to for sites in clusters 1 and 4 than in clusters indicate clearly the existence of broad 2 and. 3 The mean numbers of taxa for geographic faunal regions. Rather, the cluster 1 and cluster 4 were 27 and 26, heterogeneity of site groupings is more respectively. Cluster 2 and cluster 3 had suggestive of grades of habitat quality. If chironomid species diversity proves to be correlated highly with environmental Otcl 12