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Physical habitat measurements were taken at all areas seined. __ Maximum water depth, length and width of habitat and of area seined, and water depth at the midpoint of the long axis of the backwater and water depths midway between the shorelines and the midpoint were recorded at each backwater. In deep backwaters, where seine hauls began and ended on the same shoreline, the deepest depth and depths 1/3 and 2/3 of the distance between the shoreline and the outside edge of the sampled area were measured. The size of the predominant and second most common substrate on either side of the maximum seining . depth was estimated and recorded. The silt/mud depth at the midpoint of the long axis of the backwater was also recorded. Data for each seine haul also included water temperature at the midpoint of the long axis of the habitat, and water temperature in the mid-channel of the river adjacent to the habitat seined. ~ Data for 1987 from the U.S.G.S. Bluff, Utah gaging station that is used in this report is provisional and subject to change. Results and Discussion ~ Occurrence and Distribution of Rare Fishes Gill netting, electrofishing, and seining results documented the presence of the endangered Colorado squawfish in the San Juan River, Utah. On April 7, 1987 BOR collected, tagged (tag number 00070) and released a 637 mm Colorado squawfish in the San Juan Arm of Lake Powell. UDWR completed a total of 94 hr of electrofishing which resulted in the capture of a single Colorado squawfish. This Colorado squawfish was the same fish collected, tagged and released by BOR. UDWR collected and released the fish at RMI 89.8 during nighttime tar- get electrofishing on 8 September 1987. One other Colorado squawfish ~ was shocked at RMI 90.4 on 11 June 1987, -but it could not be cap- tured. Forty-three habitats were seined by UDWR, five during the spring, and 38 during the fall standardized YOY seining. Six YOY Colorado squawfish were collected by UDWR during fall standardized seining -- one at RMI 101.7, two at RMI 99.5, and three at RMI 94.5. Thirty-five sites were seined by BOR, 20 during summer, and 17 during ~ fall standardized YOY seining. Fall standardized seining by BOR pro- duced nine YOY Colorado squawfish. Two were collected at RMI 14.3, four at RMI 9.4, two from a second backwater at RMI 9.4, and one at RMI 6.0. Seining by UDWR produced two specimens of Gila sp.; these fish ~ have not been identified to species, but they are thought to be roundtail chub. One of these Gila sp., a juvenile was collected at _ RMI 103 in the spring. The other was a YOY Gila sp. collected at RMI 93.5 during fall standardized seining. Although razorback sucker are thought to be present in the San ~ Juan River, no specimens were encountered during this study in - 11 -