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4t I., INTRODUCTION The Colorado River is home to some of the most unique fresh water fishes in the world. Four of these native "big river fishes" are now dangerously close to extinction -- the Colorado squawfish, the humpback and bonytail ct}ubs, and the razorback sucker. Historically, these four fishes were found in abundance throughout the Colorado River and its major tributaries, which are legally divided into Upper and Lower Basins at Lee Ferry on the Colorado River mainstem just below Glen Canyon Dam. Currently, the Colorado squawfish has been extirpated from the Lower Basin, except for any remnants of re-introduced, experimental populations, but natural populations still persist in the Upper Basin. The squawfish populations in the Yampa and Green Rivers of the Upper Basin have been greatly reduced but may be fairly stable. The bonytail is the rarest, with very few captures in the wild in the last decade. The humpback chub, which was not described as a separate species until 1946, may be most numerous in the Lower Basin, in and near the confluence of the Colorado and Little Colorado Rivers in the Grand Canyon. Humpback populations persist in the Upper Basin in the Yampa, Desolation, Gray, Cataract, Black Rocks, and Westwater Canyons. The razorback sucker was once widely distributed, but today its populations are mostly older fish, concentrated in the mainstem reservoirs on the lower Colorado River, most notably Lake Mohave, and in the lower Yampa and Green Rivers of the Upper Basin. Five other native fishes might be included with these four in a community that inhabits the deeper and warmer habitats of the Colorado River system -- the roundtail chub, the fannelmouth sucker, the bluehead sucker, the woundfin, and the speckled dace. Each of these big river fishes is also in serious decline. Two major reasons are cited for the decline of these fishes. First, dam construction over the past century has fragmented their habitat and has reduced or altered flows for significant reaches of river, which has disrupted their natural life cycles. See Figure 1. Second, the introduction of a wide variety of non-native fishes into the system and their proliferation in reservoirs and warm water habitats is also thought to be a very significant factor in the decline of the native, big river fishes. The introduced non- natives both compete with and prey on the native fishes. This paper will first review the principal features of the Endangered Species Act (ESA) which have been applied to the squawfish, razorback, and the two chubs. Many of these features are currently being scrutinized by Congress and could be amended in the near future. This paper will then examine the two programs that have been developed in the Upper Colorado River Basin, and the one that is emerging in the Lower Basin, for implementing the recovery of the Colorado River fishes that have been listed under the ESA and for complying with the regulatory features of the ESA. These programs are organized around the regional jurisdictions of the most responsible federal agencies -- the Upper Basin Program falls within the purview of Region 6 of the U.S. Fish and Wildlife Service (FWS) and the Upper Colorado Region of the U.S. Bureau of Reclamation (BOR); the San Juan Program is the concern of Region 2 and 6 of the FWS and the Upper Colorado Region of the BOR; and the Lower Basin is mostly within Region 2 of the FWS and the Lower Colorado Region of the BOR. This paper addresses the relatively recent development and policies of these recovery implementation programs and is not a complete history. This paper's main concern is that the recovery of the listed fishes may be frustrated by the split in the regional jurisdictions of the most responsible federal agencies, by the inattention to the recovery goals set for the full geographic range of these fishes, or the absence of such goals in the case of the razorback, and by a consequent but not always apparent divergence of opinion as to how recovery should be defined. This paper's most important conclusion is that the range-wide recovery planning and goal setting for these 1