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M, <br /> Mid-Continent Resources'Stream Impairment Study <br /> OWN <br /> low flow, Stations 5 and 7 had levels less than at Station 4 but higher than at Stations 1 and 6. <br /> These same patterns were reflected for conductivity. <br /> During the field investigations, a white precipitate was observed on the banks of Sites 2, 3 <br /> and 4. Alkalinity and particularly sulfate levels tended to decrease downstream at these stations. This <br /> suggests the precipitate was either calcium sulfate or calcium carbonate. <br /> Table 1. Sulfate,Alkalinity,and Conductivity values measured at the various sampling stations. The first number represents <br /> value for spring period;the second number was collected in fall. Concentrations are in mg/I except for conductivity which <br /> is µmhos/cm. <br /> Station 1 2 3 4 5 6 7 <br /> Alkalinity 34/98 1370/1642 1348/1662 1082/1575 62/752 60/164 94/462 <br /> Sulfate 3.5/15.0 1100/650 750/680 550/620 10/300 8.5/56 25/180 <br /> Conduc- 97/238 3490/3830 3550/3950 3010/3970 186/1870 133/373 257/1196 <br /> tivity <br /> During high flow, Dutch Creek at Site 5 had a flow ten times that of the discharge stream <br /> as measured at Site 4. In the fall, dilution rates dropped to less than 2:1 and the discharge stream <br /> became a major component of Dutch Creek. This was reflected in sulfate, alkalinity and conductivity <br /> measurements at Site 5 which were approximately 50% of those measured at Site 4. <br /> During high flow at Site 7, sulfates, alkalinity, and conductivity were higher than at Site 5. <br /> This was in spite of lower values at Site 6 which was diluting Coal Creek. These data suggest <br /> another source of TDS between Sites 5 and 7, although such a source has not been identified. <br /> Biomonitoring Test Resells. Results of the Ceriodaphiria debia biomonitoring tests are found <br /> in Appendix 2 . Survival and LC50 values are summarized in Table 2. <br /> During the high flow period, acute effects were found in the discharge waters of Sites 2 and <br /> 3. In September Sites 2,3 and 4 were toxic. This probably reflects the lower dilution of the <br /> discharge waters during low flow periods. <br /> Table 2. LC50(%effluent)for each station measured during high and low flow periods. <br /> Stations 1 2 3 4 5 6 7 <br /> Spring >100 86.6 97.6 >100 >100 >100 >100 <br /> Fall >100 67.3 64.1 48.8 >100 >100 >100 <br /> The SeaCrest Group <br />