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<br />002333 <br /> <br />Channel catfish: the Flaming Gorge outlet works preclude virtually all warm <br />water fish escapement; routine stocking is restricted to isolated ponds and <br />reservoirs outside the 100 year floodplain because reproduction by catfish is <br />likely to be very good in upper basin rivers, and stocking would augment or <br />supplement existing wild catfish populations. <br /> <br />Utah chub: continued use in Utah subbasins where they currently exist because <br />that should not allow for additional range expansion. <br /> <br />mosauitofish: routine stocking restricted to isolated ponds. and reservoirs <br />outside the 100 year floodplain because they are aggressive omnivores that <br />have been associated with the extirpation of many rare, localized native fish <br />species in the American Southwest. Mosquitofish are currently common (as a <br />result of stocking) in habitats used as nursery areas by endangered Colorado <br />River fish. <br /> <br />6.500 feet msl contour line: was chosen by professional fishery biologists as <br />a level that affords reasonable confidence that stocking of certain nonnatives <br />(only crappie, bluegill, largemouth bass, catfish, mosquitofish, and carp) in <br />isolated ponds will not adversely impact listed species. Coldwater stream <br />conditions above 6,500 feet msl are not conducive to the survival of escaping <br />warmwater fishes. There are very few floodplain situations above 6,500 feet <br />msl where isolated ponds occur and where they do exist they are typically <br />stocked with salmonids. The isolated ponds located above 6,500 feet msl are <br />far from critical habitat. <br /> <br />5 feet above ordinary hiah water line: approximates the 50 to 100 year <br />floodplain on an interim basis based primarily on professional judgement and <br />field observations of FWS and State hydrologists working with rivers and gage <br />rating tables in the Upper Colorado River Basin.. Because of the difficulty of <br />developing floodplain maps in the very near future it was felt that some <br />relatively simple method for approximating the 40 and 100 year floodplains <br />which would be reasonably accurate and relatively easy to define on-site would <br />be helpful until maps can be developed. This would allow for some measure of <br />control of nonnative stocking while regulatory procedures (including detailed <br />maps) are being developed. The alternative is to forego any oversight of <br />aquaculture or recreational fish stocking for 1 year while these details are <br />being completed. <br /> <br />The 5 feet criteria should be considered as a starting point which will be <br />refined by further hydrologic studies. It is entirely possible that the <br />delineation may change from basin to basin based upon topography and <br />elevation. Hydrological studies may indicate that other elevations such as <br />4 feet and 6 feet may be more accurate estimators nf the floodplains of <br />concern. It may even be concluded that this method is too variable and will <br />not work. <br /> <br />Ordinarv Hiah Water line (OHWl): this is the water level which represents the <br />water surface elevation during a normal (annual) high water event. The <br />physical evidence denoting the OHWl is the point where perennial hydrophytic <br />plant life converges with bare substrate (rock, gravel, sand, fines) or with <br />substrate interspersed with annual vegetation. <br />