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3 . part of the depletion allocation for NIIP. . Exterior to the NIIP project, the Navajo Nation owns two irrigation projects with diversion dams impacting the movement of fish within the San Juan River. As a part of the completion of NIIP, these dams will be modified by the Bureau of Indian Affairs to remove impediments to passage by Colorado pikeminnow, thereby allowing access by the species to portions of its designated critical habitat upstream from the diversion dams and removing the potential threat of entrainment of downstream moving fish. Cudei Diversion Dam is located about 6 miles downstream of Ship rock on the San Juan River. The quarry rock dam spans the entire width of the river as it diverts water to the Navajo-owned Cudei Irrigation Project. This is the lowermost diversion dam on the San Juan River. To allow expansion of range, plans are underway to remove the diversion dam, replacing it with a 21-inch diameter inverted siphon crossing under the river. Construction is anticipated for fall/winter of 1999/2000 or 2000/2001. The Hogback Diversion Dam crosses the San Juan River about 10 miles east of Shiprock, diverting water for the Navajo Nation's Hogback Irrigation Project. The quarry rock diversion dam has failed and the diversion is maintained by bulldozing up a dike across the river during low flow periods and routing most of the water through the canal intake and sluiceway. During storms and other high water events the dike is again breached and must be re-built. The Bureau of Reclamation is currently designing a low gradient riprap dam with steel sheet pile cutoff wall to replace the existing temporary dike arrangement. A low-flow fish passage channel will be incorporated into the structure adjacent tot the sluiceway. At high flow, the entire structure will be passable by most fish species.. Downstream moving fish, including larval drift, will pass through the fish passage channel. The Biological Assessment addressed the potential of the project to affect listed,' proposed, and candidate species, and species of concern. For listed species the Biological Assessment provided the following findings: Black-footed ferret (Mus tela nigripesJ - No effect. The Service concurs, based on the lack of any prairie dog colonies on or adjacent to the project. American pereqrine falcon/arctic pereqrine falcon (Falco peregrinus anatum/F. p . tundriusJ No effect. The Service concurs, based on the lack of nesting habitat on project lands. Any use of the project area would be incidental and associated with movements between areas of suitable habitat. Bald eaqle (Haliaeetus leucocephalusJ No effect. The Service concurs; although bald eagles winter in small numbers along the San Juan River, the project area does not contain suitable habitat or forage species of concentration to attract feeding eagles. The reoperation of Navajo Dam that is considered a component of this project will return the management of the San Juan River to a more natural hydrograph. Such modification of flows may affect fish populations but is not expected to result in discernible changes in the availability of fish as prey for the eagles. .