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08/09/99 MON 17:06 FAX 801 524 5021 Invertebrates USFWS-Utah Field Office 44-+ RO-COKANUT IN09 Two samples of crayfish were collected in Stewart Lake at the J3 Channel (Figure 4) in May and June which contained selenium concentrations of 16.1 and 13.4 µg/g dw, respectively. These concentrations are elevated above the Toxicity Threshold of 3 µg/g dw for dietary items. One sample of crayfish was collected in backwater SL1 which is located at the new inlet to Stewart Lake between the river and the road. The selenium concentration was 4.28 µg/g dw. Though this concentration is above the Toxicity Threshold for dietary items, it is substantially lower than those collected in the J3 Channel. Sediment One sediment sample was collected in an area referred to as the "Frog Pond", which lies approximately 30 meters south of the J5 inflow to Stewart Lake. The selenium concentration was 2.56 µg/g dw. A total of 10 sediment samples were collected from backwater locations on the Green River during 3 sampling periods. Selenium concentrations ranged from less than detection (<1.00 gg/g dw; 7 samples) to 1.55 µg/g dw. Both samples collected below Ashley Creek were above detection and one sample from SL5 (close to Marsh 4720) was also above detection. Composite fish A total of 19 composite fish samples were collected from 5 backwater locations. Selenium concentrations ranged from 2.26 to 14.1 gg/g dw. Seven different fish species were analyzed for selenium. Geometric means for the backwaters ranged from 3.0 to 7.3 µg/g dw, with SL3 (below Ashley Creek) being the highest (Table 9). Backwater SL4 was not sampled in 1998 though it was sampled in 1997. The backwater located at JB2 was approximately 100 m downstream of the location in 1997 (JB 1). Though there is a distinction made between these two sites, they should still be comparable since they are reasonably close. Table 9. Geometric means of selenium in composite fish from backwaters in 1998. Below Jensen Bridge (JB2) 3.9 3.0 -23.0% Stewart Lake Inlet (SL1) 5.2 5.5 +4.8% Stewart Lake Outlet (SL2) 3.9 3.5 -11.2% Below Ashley Creek (SL3) 5.4 7.3 +35.8% Above Red Wash (SL4) 4.7 -- Below Red Wash SL5 5.6 6.0 +7.6% Totals 4.9 4.4 -10.2%