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. , .. suckennouth minnow (Phenacobius mirabilis) historically inhabited this reach of the Arkansas River but have been absent from recent fishery surveys. Flathead chub (P/atygobio graci/us) and suckennouth minnow (Phenacobius mirabilis) have been identified by the DOW and several other state and federal . agencies as "species of greatest conservation need". As directed by Colorado's 2005 Comprehensive Wildlife Conservation Strategy (CWCS), DOW is involved in developing conservation and management plans for these species. The intention ofthese plans is to increase populations and distributions ofidentified species, thereby assisting in the long-tenn persistence of each species. The success of such plans could potentially curtail the need for federal listing of these species under the Endangered Species Act (ESA). These species are not currently federally listed. Instream Flow Survey Data The DOW, in September of2005 and March of2006, collected stream cross section infonnation, natural environment data, and other data needed to evaluate the proposed 100 cfs instream flow recommendation, The stream cross section data was analyzed using the R2CROSS program, The R2CROSS output was evaluated using the methods described in Nehring (1979) and, Espegren (1996), DOW collected physical data at four different cross-section locations at three different discharges (see attached map). The observed flows ranged from a high of260 cfs to a low of 58 cfs. The width of the Arkansas River at the four study sites ranged from 160 feet to 132 feet. X-Section Locations Data relating to the individual x-sections are discussed below: . Site # I is located approximately Yo mile downstream of Pueblo Dam. The bank full width ofthis x- section was 151 ft and had a hydraulic slope ofless than I %. Data collection flows at this site included flows of 58, 89. 155 and 260 cfs, . . Site #2 is located near the eastern end of Lake Pueblo State Park, approximately 2 miles downstream of Pueblo Darn, The bank full width of this x-section was 132 ft and had a hydraulic slope ofless than I %. Data collection flows at this site included flows of 92, 155, 178 and 264 cfs. . Site #3 is located approximately 100 yards down-stream of the railroad bridge crossing the Arkansas River near Reservoir Road. The bank' full width of this x-section was 160 ft and had a hydraulic slope ofless than I %, Data collection flows at this site included flows of85, 155, 174 and 252 cfs. . Site #4 is located approximately Y. mile upstream oCthe confluence with Fountain Creek. The bank full width of this x-section was 141 ft and had a hydraulic slope of less than I %. Data collection flows at this site included flows of 82, 136 and 223 cfs. DOW evaluated the stream flow hydraulics and channel characteristics which occur at the proposed 100 cfs flow recommendation, see Table I below. Table 1: Stream Flow Hydraulics and Channel Characteristics at 100 efs X-section % Wetted Perimeter Avera2e Depth #1 - Below Reservoir 69.8% 0.89 feet #2 - Lower State Park 72,0"10 0,76 feet #3 - Below RR-Xing 75.9% 0.53 feet #4 - Above Fountain Ck 61.3% 0,53 feet A vera2e Velodty 1.06 ft/s 1.33 ft/s 1.54 ft/s 2.19 ft/s A 100 cfs instream flow would provide: . Enough water to wet approximately 70"10 ofthe stream channel at 3 ofthe four x-section locations and 61 % ofthe stream channel at X-section #4; . An average depth of close to 0.5 feet at all four x-sections and nearly 0,9 feet at X-Section #1; and . An average velocity of over 1.0 feet per second at all x-sections. .