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Yrt. j. <br />EC'd. <br />I `'p <br />L: <br />METHODS <br />A two species acute bioassay was conducted with effluent from the West Fork of Sylvester <br />Gulch, outfall 017. An efluent grab sample was collected on July 11, 2001, stored on ice, and <br />delivered to Commercial Testing and Engineering, Co. (CT&E) on the following day. The <br />effluent sample was received at a temperature of 20.0 ° C and assigned CT&E sample tracking <br />number 72-455426. The bioassay was initiated approximately 22.5 hours after sample <br />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 1. <br />Basic characteristics of the efluent and dilutions were measured as follows: <br />~.-:• <br />Characteristic Method/Equipment EPA Method <br />~' `? Alkalinity Titrimetric (APHAt, 1989) EPA 310.1 & 130.2 <br />Ammonia Lachat Analysis Method EPA 350.1 <br />Chlorine, Total Residual LaMotte 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 NiST2 calibrated thermometer EPA accepted <br />' The tests exposed daphnids, Daphnia magna, to five concentrations of effluent, 100%, 75%, <br />~'`' S0%, 25%, and 1.9%, prepared using reconstituted laboratory water at 110 mg/L CaC03. <br />Additionally, the tests exposed fathead minnows, Pimephales promelas, to five concentrations of <br />f : effluent, 100%, 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 />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 /> <br />I American Public Health Association <br />' National Institute of Standards and Technology <br />2 <br />I.' <br />C~' <br />COMMERCIAL TESTING & ENGINEERING CO. <br />L F466 <br />i ' LTA <br />'Original Watarmarketl For Vour Protection <br />