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<br />The u.s. Fish and Wildlife Service collected 12 fish samples, including <br />6 trout, from Ridgway Reservoir and the Uncompahgre River downstream from <br />Ridgway Reservoir in 1987-88. The fish were analyzed for trace elements, and <br />results are listed in table 7. In at least one of the fish samples, concen- <br />trations of arsenic, cadmium, copper, lead, and selenium exceeded the 85th- <br />percentile concentration (Lowe and others, 1985) for fish samples collected in <br />1980-81 for the National Contaminants Biomonitoring Program (NCBP). The NCBP <br />85th percentile for arsenic was exceeded in two samples. Cadmium concentra- <br />tions in 10 of the 12 samples listed in table 7 exceeded the NCBP 85th percen- <br />tile for cadmium. All concentrations of copper (table 7) exceeded the 85th <br />percentile for copper (0.9 ~g/g wet weight or 3.6 ~g/g dry weight at 75 <br />percent moisture). The lead concentration of 20 ~g/g dry weight (4.3 ~g/g wet <br />weight) in a white sucker collected from the Uncompahgre River was much larger <br />than the NCBP 85th-percentile concentration of 0.25 ~g/g wet weight (1.0 ~g/g <br />dry weight at 75 percent moisture). The NCBP 85th percentile for selenium <br />(0.77 ~g/g wet weight or 2.8 ~g/g dry weight at 75 percent moisture) was <br />exceeded in all six trout samples. Zinc concentrations in seven of the fish <br />samples exceeded the NCBP mean concentration for zinc, but none of the zinc <br />concentrations exceeded the 85th-percentile concentration of 160 ~g/g dry <br />weight. Mine drainage into the Uncompahgre River upstream from Ridgway <br />Reservoir is the most likely source of the trace elements. All mercury <br />concentrations were less than the NCBP 85th-percentile concentration <br />(0.18 ~g/g wet weight or 0.72 ~g/g dry weight at 75 percent moisture). <br /> <br /> Table 7.--S.1ect.d trace-element data {or whole-body (ish samples collected from <br /> the Uncompahgre River and Ridgway Reservoir in 1987-88 <br />IAnalyses by U.S. FIsh and Wlldlife Servlce; concent~ations are in microgram~ per gram dry welght; <br /><, l~sa than; nwnbers in parentheses are the 85th-percentile concentratlons In dry welgbt of the <br />Nat ional ContamInants Blomonltorlng Program. The 85th percentiles were reported in wet-weIght <br />concentrations and were converted to dry-weight conc~ntrations at 75-percent moisture) <br /> Alum- Arse- Cad- Chro- Coppe r Lead Mer- Sele- <br />Species Year nic Illiwn Molyb- Zlnc <br /> inum miwn (3.6) ( 1.0) cury Nickel n,um <br /> (0.88) (0.24) (0.72) dcnum (2.84) (160) <br /> RIDGWAY RESERVOIR <br />Brovn trout 1988 12 0.30 <2.0 <1.0 8.2 <4 0.15 <1.0 <I 4.0 99.8 <br />Rainbow trout 1987 547 .93 .48 <2.0 6.4 <.5 .35 .2 .5 3.4 90.8 <br />Rainbow trout 1988 290 .40 <2.0 2.0 10 <4 .16 <1.0 <I 6.0 133 <br />White sucker 1987 464 .38 .49 <2.0 5.8 <.5 .09 .3 .6 2.7 57.3 <br />White sucker 1988 310 .30 .40 3.0 5.9 <4 .18 <1.0 <I 1.6 59. I <br /> UNCOMPAHGRE RIVER BELOW RIDGWAY RESERVOIR <br />Brown trout 19B7 4 .37 .40 <2.0 14.8 <.5 .12 .2 .4 4. I B9.5 <br />Brown trout 19B8 220 .30 .60 2.0 19.5 <4 .12 <I .0 <I 4.6 109 <br />Rainbow trout 1988 200 .70 1.3 2.0 19 <4 .10 <l.0 <I 2.9 142 <br />Whi te sucker I9B7 190 .30 .30 <2.0 4.8 <.5 .21 .3 .6 1.8 83 <br />Whi te sucker 1988 1,740 2.2 1.2 10 20 20 .08 < 1.0 4.0 1.9 145 <br />Mottled sculpin 1987 210 .34 .66 <2.0 6.0 .6 .08 .2 .6 2.2 131 <br />Mottled sculpin 1988 321 .40 1.3 3.1 8.4 <4 .08 <1.0 2.0 2.8 150 <br /> <br />28 <br />