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The eight streams of cluster B (Figure 7) included five from the northwestern and three from the northeastern reaches of the basin. These streams all had relatively moderate species richness (average=32); and all were much smaller in size when compared to cluster A streams, in terms of watershed area (average=1119mi²), stream length (average=107mi), and average annual discharge (average=119cfs). Within this cluster, two subgroups can be noted. The Pembina, Forest, Park, and Turtle Rivers from the western basin formed one subgroup indicating close faunal similarity among these streams. The Roseau, Two, and Sandhill Rivers from the eastern basin, along with the Goose River, formed a second subgroup. This separation suggests that differences in fish faunas of streams may be due to an east-west environmental gradient as is noticed across the Red River basin (Stoner et al. 1993). Through PCA, the species descriptive of cluster B streams could not be distinguished because streams did not score high on a common PCA axis.

The seven streams of cluster C all were located in the west-central and southern reaches of the basin. These streams were characterized by relatively low species richness (average=21), moderate watershed area (average=933mi²), low stream length (average=76mi), and average annual discharge (average=42cfs). Within this cluster, two subgroups can be noted. The Elm, Rush, and Maple Rivers formed one subgroup, indicating extremely close faunal similarity, particularly between the Rush and Maple Rivers. The Wild Rice, Bois de Sioux, Mustinka, and Rabbit Rivers formed a second subgroup. These streams are all located in the extreme southern reaches of the basin. Through PCA, the species descriptive of cluster C streams were determined. The channel catfish, river shiner, spotfin shiner, bigmouth buffalo, and sauger were most descriptive of the Maple and Bois de Sioux Rivers along with the Sheyenne and Red Rivers of cluster A. Results of the PCA are questionable in this case because the river shiner and sauger are not typically found in the Maple and Bois de Sioux Rivers (Figures A29 and A75).

Cluster D was a small group consisting of only four streams, the Tamarac, Snake, and Middle Rivers in the northeastern basin and the Tongue River in the northwest. These streams were characterized by low species richness (average=20) and extremely small stream size in terms of watershed area (average=400mi²), stream length (average=41mi), and average annual discharge (average=41cfs). The central mudminnow, pearl dace, and finescale dace were identified by PCA as species typical of cluster D streams. Analysis of distribution patterns also indicates that these species are common in all four streams (Figures A24, A39, and A52). The only record of the central mudminnow from the Red River basin in North Dakota is from the Tongue River.