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Final Report 3-6 September 2000 began in 1967. In the second phase, from 1967 to 1978, Flaming Gorge Dam was operated with few constraints, and water releases were made from deep within the reservoir through the single outlet structure. The only constraint on releases during that period was the 23 m3/s minimum release to establish and maintain the tailwater trout fishery (Smith and Green 1991). The dam was retrofitted with a multilevel outlet to improve water temperatures for the tailwater trout fishery in 1978. Aside from the use ofthe multilevel outlet structure, operations in the third phase, from 1979 to 1984, were similar to those in the previous phase (Smith and Green 1991). An interim flow agreement was established in 1985 to change Flaming Gorge Dam releases to protect endangered fish nursery habitats in the Green River downstream of Jensen, Utah (Smith and Green 1991). The interim agreement provided for a maximum release volume of 123.4 million m3 in August and September, with daily fluctuations at the dam between 23 and 68 m3/s. The recommended releases were based on observations made in 1985 that indicated that "good" habitat conditions were available at lower flows. Reclamation also changed operational criteria at the dam to avoid spills, such as those that occurred in 1983 and 1984. These changes were in place in the fourth phase, from 1985 through 1992, along with numerous research releases to support preparation of the 1992 Biological Opinion. Most recently, in the fifth phase, operations at Flaming Gorge Dam have incorporated recommendations of the 1992 Biological Opinion, including providing flows needed for the Flaming Gorge Flow Recommendations Investigation (Section 1.3). Flows recommended in the Biological Opinion were intended to restore a more natural hydro graph and protect nursery habitats of endangered fishes downstream of the Yampa Ri ver confluence. The Biological Opinion called for a full power-plant-capacity release (133 m3/s) each spring and included recommendations for target flows in summer and autumn (31 to 51 m3/s), with fluctuations in flow at Jensen constrained to 25% of target flow to protect nursery habitats in this reach. Releases during the winter were held steady once an ice cover formed in the Jensen area (generally December through February) to protect endangered fish habitats. 3.3 DESCRIPTION OF GREEN RIVER REACHES DOWNSTREAM OF FLAMING GORGE DAM The longitudinal profile of the Green River downstream from Flaming Gorge Dam includes steep and flat segments, and the gradients of these segments do not systematically decrease in a downstream direction (Figure 3.2). In general, low-gradient reaches of the river have sandy substrates, but segments with steeper gradients have gravel or cobble substrates (Schmidt 1996). For this report, the Green River is divided into three reaches delimited by major tributaries (Figure 2.1). Reach 1, between Flaming Gorge Dam and the Yampa River confluence, is about 104 kIn in length (Figure 2.1). Flow in this reach is measured at the USGS gage near Greendale, Utah. Reach 1 is straight to meandering and, with the exception of Browns Park, tightly confined by the ~