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<br />OOC9 <br /> <br />11. Total abundance of aquatic macroin- <br />vertebrates was lower immediately downstream <br />of both the leadville Drainage Tunnel and Cali- <br />fornia Gulch. <br /> <br />12. Predominantly clean water forms of <br />macroinvertebrates were found above the <br />California Gulch inflow and heavy-metal-tolerant <br />forms were found below. <br /> <br />13. Fish populations were reduced in the up- <br />per Arkansas River below the leadville Drainage <br />Tunnel discharge and absent immediately below <br />the California Gulch inflow. <br /> <br />14. Heavy metal concentrations in brown trout <br />liver showed bioaccumulation of copper and <br />zinc, indicating chronically high concentrations <br />of these metals in the water. <br /> <br />1 5. It is difficult to determine precise concen- <br />trations of heavy metals that would be toxic to <br />aquatic life. The toxicity is dependent on water <br />quality conditions. sediment characteristics, <br />properties of the metal. and the particular <br />organism tested. Fish and aquatic macroinverte- <br />brates were collected at stations having heavy <br />metal concentrations in excess of documented <br />toxic levels. This indicates that these metals <br />may not always be in a highly toxic form. <br /> <br />REVIEW OF LITERATURE <br /> <br />The purpose of this section is to familiarize the <br />reader with the history of the study area, sam- <br />pling techniques. and important aspects of <br />various water quality parameters. <br /> <br />Historical Review <br /> <br />The greatest heavy metals pollution of the upper <br />Arkansas River and its tributaries is thought to <br />have begun in 1 860 with the discovery of placer <br />gold along California Gulch (Ubbelohde, 1964 <br />1152\). Intense mining, primarily for gold and <br />silver, continued in the area until 1893. These <br />mines contained ores of copper, iron, zinc, and <br />lead, which were considered waste and were <br />deposited in large tailing piles in gulches and <br />creek beds (Ubbelohde et aI., 1971 [1531 J. <br /> <br />Removal of trees from the hillsides for use in the <br />mining operations resulted in increased runoff. <br />erosion, and the consequent pollution of the <br /> <br />streams in the area. Abandoned mines filled with <br />water. overflowed. and compounded this pollu- <br />tion problem. Mining in the area intensifed dur- <br />ing World War I and declined during the 1930's. <br />An increase in mining activities was seen again <br />during World War II, with a decrease during the <br />postwar period. <br /> <br />At the present time, the major mining operation <br />in the area is the Climax molybdenum mine. No <br />known heavy metals contamination is released <br />from its operation down the East Fork (Arkansas <br />River). ASARCO is operating the Black Cloud <br />Mine. which discharges wastes down Iowa <br />Gulch. and it appears that recent increases in the <br />prices of metals. particularly silver and gold, will <br />cause other mining activity in the areas to in- <br />crease. Placer mining, both large and small <br />scale, may increase, and abandoned mines and <br />mills may again begin operating (Wilkinson, <br />1980 [16811. <br /> <br />Sampling Apparatus for the Collection of <br />Macroinvertebrates <br /> <br />Variations in accessibility and substrate make <br />sampling lotic environments extremely difficult. <br />Many times the collection of samples is the <br />weakest part of an environmental surveillance <br />program. A standard sampling system should be <br />applied over similar habitats for best results and <br />meaningful comparisons (Hellawell, 1978 <br />[721 ). <br /> <br />Many types of samplers have been used for the <br />collection of aquatic macroinvertebrates in <br />rivers and streams. Nets. grabs, dredges, <br />shovels, cylinders, boxes, and core samplers <br />have all been employed in these collections. A <br />large number of benthic samplers have been <br />described for quantitative and qualitative collec- <br />tions of aquatic insects (Welch. 1948 [1631; <br />Cummins. 1962 [311; and Weber, 1973 <br />[1611 I. The depth of the water, substrate type <br />and size. and velocity of the flow provide some <br />criteria for the selection of the optimum type of <br />sampler. <br /> <br />Surber (19371 [1441. Britt (195511141. Macan <br />(19581 11011. Bull (1968) [161. and Horning <br />and Pollard (19781 [7811 described some net <br />samplers which can be used to collect aquatic <br />insects in stony streams. These samplers are <br />usually used in flowing water with the open <br />mouth of the net facing upstream. The stones <br /> <br />5 <br />