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eM) o ...... to 0) are apparently more important when they occur in relative proximity to each other, such as in habitat-rich river reaches. Key habitats for young Colorado pikeminnow in the San Juan River include backwaters, pools, pocket waters, and other slow-velocity habitats along shorelines. Key habitats for juvenile Colorado pikeminnow were not detennined, but the fish appeared to utilize a variety of mediUlll- to slow-velocity habitats. Key habitats for subadult and adult razorback sucker in the San Juan River are slow-water habitats including eddies, edge pools, and backwaters found in relatively habitat-rich portions of the river. Cobble areas in shoreline nms are spawning locations. Habitat for young and small juvenile razorback sucker was not detennined since these size classes were not collected during the 7-year research period. Flannelmouth sucker use a great variety of habitats and do not appear to select any key habitats. Bluehead sucker and speckled dace select cobble substrates and riffle-type habitats. Roundtail chub were not common enough to detennine key habitats, although they use pools and eddies in tributaries. The habitat studies detennined that key habitats for the two endangered fish species make up only a small portion of the available habitat in the San Juan River. This is especially true of backwater and low-velocity (eddies, pools) habitats. In comparison with the Green and Colorado rivers, however, actual habitat amounts are very similar. Cobble bars for spawning are fairly common in the upper San Juan River. Quality of backwater habitats in the San Juan River is at least comparable with that in the Green and Colorado rivers, and nUlllerous cobble bars (Colorado pikemiooow spawning areas) with appropriate cobble size and cleanliness were found in the San Juan River. Late summer thunderstorm activity levels in the San Juan Basin are much higher than in either the Green or Colorado rivers, and sediment inflow from these storms has the potential to reduce the quality of backwaters, spawning bars, and other habitats in the San Juan River. Key habitats are fairly well distributed in the San Juan River, except for the canyon reach from about RM 20 to RM 65. This reach has reduced habitat richness compared with other reaches and does not have sufficient habitat to retain stocked Colorado pikemiooow. Cobble bars suitable for Colorado pikeminnow are found in the upper portion of the river (Reaches 4, 5, and 6) and backwater habitat is also fairly abundant in this upper portion of the river. River reaches with high habitat richness were relatively rare in the San Juan River, and habitat richness peaked in Reach 5. Habitat quantity and quality was not limiting to the endangered fishes during the 7 -year research period, but this may be due in part to the low nUlllbers of the two species in the river. Habitat for the other native fishes was also not limiting. Management Implications A major concern of the SOOP during the 7 -year research period was the development of flow recommendations (Holden 1999) that provide high levels of habitat quantity and quality timed to meet the critical habitat needs of the endangered fishes. The development of the flow recommendations concentrated on improving backwater and cobble bar habitat quantity and quality and providing high habitat richness. B1iesner (I999b) showed that backwater habitat quantity September 2000 3-34 Program Evaluation Report