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mean numbers of benthic macroinvertebrate taxa of 19 and 16, respectively. Fish Faunal Regions Data for fish indicated that 20 species (Table 4) were found at the 28 sites for which environmental data were also available: - Similarity among sites based on fish data was investigated several ways, i.e., with presence/absence data and with relative abundance data. Using cluster analysis on presence/absence data, three fish faunal regions were identified (numbers 1-3, Figure 10). The first cluster represented high elevation sites in the northern portion of the upper Rio Grande drainage. The mean elevation for these sites was 8186 feet. The second cluster contained lower elevation sites, mostly on the Chama River downstream from the town of Chama. The mean elevation for cluster 2 sites was 6381 feet The high elevation sites, Rio Guaje and Casias Creek. Cluster 2 included 2 sites (Rio Frijoles and Red River above the Rio Grande) where brown trout was the most abundant species. The third cluster represented three Jemez River sites that had Rio Grande sucker as the most abundant species. Four sites (cluster 4) had brown trout and longnose dace as codominant -species. -Flathead -chub was the most abundant species at three sites (cluster 5) and Rio Grande cutthroat trout was most abundant at one site (Costilla River at La Cueva, labeled 6 on Figure 11). White sucker, cluster 7, was the most abundant species at seven sites. Cluster 8 grouped sites that had longnose dace as the most abundant species. Congruence between Aquatic Ecoregions and Faunal Regions • thud chaster, with a mean elevation of 7113 feet, contained most of the Jemez River sites. Thus, cluster analysis of fish presence/absence data suggests three fish faunal regions in the upper Rio Grande that have some degree of drainage specificity. Most of the drainage specificity in fish faunal regions appears to be caused by the presence of several introduced species in the Chama River drainage, i.e., kokanee salmon and green sunfish, and the absence of white suckerat the sites sampled in the Jemez River drainage. Cluster analysis using fish relative abundance data grouped sites together by their predominant fish species. Seven clusters and one single site are identified on the cluster tree in Figure 11. Brook trout (cluster 1) was the dominant species for two The congruence between aquatic ecoregions defined by analysis of environmental variables and faunal regions for fish, benthic macroinvertebrates, and chironomids was assessed. Cluster trees were compared visually; however, the large number of sites made it impossible to ascertain objectively the degree of similarity in the comparisons. Therefore, a matrix permutation test (Dietz, 1983) was performed to assess the statistical significance of association between distance matrices for sites. Six comparisons were made, i.e., fish versus environment, chironomids versus environment, benthic macroinvertebrates versus environment, fish versus chironomids, fish versus benthic macroinvertebrates, and chironomids versus benthic macroinvertebrates. Results of the permutation tests are shown in Box 2. 3a 13