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'002286 conducted over two years (1996-97), The study included measurements of physical stream characteristics, such as river width, depths, velocities and habitat components of pools, riffles, runs and other physical attributes of the river as a function of flow, The study also investigated biological components of habitat used by both endangered species and nonnative game fish (catfish and northern pike) in the river. Endangered species studied included humpback chub in Dinosaur National Monument and Colorado pikeminnow from the Green River upstream to Craig, Colorado, In their 1999 report entitled "Determination of Habitat Availability, Habitat Use, and Flow Needs of Endangered Fishes in the Yampa River Between August and October," Anderson, Irving, Miller, and Modde estimated that rate of loss of riffle habitat, important for Colorado pikeminnow, was greatest at flows below 93 cfs in the Yampa River between its confluence with the Green River and Craig, Colorado, Their recommendation was instream flows in late summer and early autumn should not fall below 93 cfs at any greater frequency, magnitude or duration than they had historically, They further recommended that a water management plan be developed to allow for future water development for humans while protecting instream flows for fishes, The researchers concluded that flow variability is a natural yearly occurrence in the Yampa River both within years due to rainstorms and in-between years due to longer-period wet and dry cycles, Native species evolved in this highly variable environment and benefit from it. Therefore, some variability is needed for a healthy ecosystem in the Yampa River. The research also emphasized that, if possible, prolonged periods of very low base flows should be avoided, They acknowledged that low base flows occurred prior to irrigation and that very low flows would occur in drought years even if irrigation were not present, but low flows could adversely impact fish during droughts, They concluded that it was best to avoid inducing extended droughts that would not occur naturally and to which the fish have not adapted, Fish may be unable to recover from prolonged droughts or long periods of lower than normal base flows year after year. 3.2 Non-Native Fish Studies and Yampa River Basin Aquatic Wildlife Management Plan Concurrent with the research conducted on summer low flow needs offish in the Yampa River, the Colorado Division of Wildlife (Division) prepared an Aquatic Wildlife Management Plan for the Yampa River Basin in Colorado, The purpose of this document was to provide management perspectives and recommended actions for aquatic resources and wildlife species managed by the Division in the Yampa River Basin, The objectives of the plan were to: 1, Describe the physical fishery and aquatic resources in the basin subject to management by the Division 2, Discuss policies, agreements and issues influencing the management of these resources 3, Discuss fishery management for specific waters and aquatic wildlife species located within the basin via management categories 4, Describe preferred fishery and conservation management recommendations for the basin and activities which are or will be undertaken to achieve agency goals and agreements, Draft 07/28/99 8 Ayres Associates