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1 <br /> <br />' METHODS <br />A two species acute bioassay was conducted with effluent from the West Fork of Sylvester <br />' Gulch, outfal] 017. An effluent grab sample was collected on January 3, 2001, stored on ice, and <br />delivered to Commercial Testing and Engineering, Co. (CT&E) on the following day. The <br />efluent sample was received at a temperature of 7.5 ° C and assigned CT&E sample tracking <br />number 72-444189. The bioassay was initiated approximately 27 hours after sample collection. <br />' Testing was conducted in accordance with the most recent protocols specified by the Water <br />' Quality Control Division of the Colorado Department of Health (1998), outlined in Table I. <br />Basic characteristics of the effluent and dilutions were measured as follows: <br />' Characteristic Method/Equi~ment EPA Method <br />' Alkalinity Titrimetric (APHAt, 1989) EPA 310.1 & 130.2 <br />Ammonia Lachat Analysis Method EPA 350.1 <br />Chlorine, Total Residual La,'~1otte STC-CI Colorimeter EPA accepted <br />' Conductivity Orion Model 160 Cond. Meter EPA 120.1 <br />Dissolved Oxygen Orion Model 850 DO Meter EPA 360.1 <br />Hardness Titrimetric (APHA, 1989) EPA 310.1 & 130.2 <br />' pH Fisher Model 925 pH Meter EPA 150.1 <br />Temperature NISTZ calibrated thermometer EPA accepted <br />The tests exposed daphnids, Daplrrrra magira, to five concentrations of effluent, 100%, 75%, <br />50%, 25%, and 1.9%, prepared using reconstituted laboratory water at 225 mg/L CaCO~. <br />Additionally, the tests exposed fathead minnows, Pimephales promelas, to five concentrations of <br />r effluent, ]00%, 75%, 50%, 25%, and 1.9%, prepared using reconstituted laboratory water at 110 <br />mg/L CaC03. Control replicates were exposed to 100% laboratory water. <br />~, <br />' The Binomial and Probit methods determined the LCso's, where applicable. Significant <br />differences in mortality were analyzed using Steel's Many-One Rank tests. <br />1 <br />~. <br />American Public Health Association <br />' 'National Institute of Standards and Technology <br />2 <br />1 COMMERCIAL TESTING & ENGINEERING 1:0. <br />~ F.~ L1E. <br />Original Watertnarketl For Your Protection ;,ter ~w.. <br />