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determined from gaging-station records was as <br />follows: good at three sites (8 percent or <br />less), fair-to-poor at one site (39 percent), <br />and poor at one site (87 percent). At the <br />three sites that showed good comparisons, there <br />was flow at every monthly visit and the sites <br />were above most diversions. The site where <br />comparison was fair-to-poor is affected by <br />upstream diversion; at the site where the <br />comparison was poor, the stream was dry at the <br />time of many of the monthly visits. <br />117. Davies, P. H., and W. H. Everhart. 1973. SPORT ~I,SH. <br />Effects of chemical variations in aquatic TOXICANT <br />environments: lead toxicity to rainbow RESEARCH <br />trout and testing application factor <br />concept. U. S. Environmental Protection <br />Agency, Washington, DC. Report No. EPA- <br />R3-Ollc. (Abstr.) <br />Four chronic bioassays were conducted to determine <br />the toxicity of lead to rainbow trout. Results <br />obtained from acute and chronic bioassays in <br />hard water (alkalinity 243.1 mg/liter) and soft <br />water (alkalinity 26.4 mg/liter) were used to <br />test the application factor approach as related <br />to different water qualities. The toxicity of <br />lead to rainbow trout in hard water was determined <br />on a total and dissolved lead basis. The 96-hr <br />TL pp and "MATC" on a total lead basis were 471 <br />mg~liter and 0.12 to 0.36 mg/liter respectively, <br />which yielded an application factor of .0002 to <br />.0008., Analysis of the free or dissolved lead <br />gave a 96-hr TL50 of 1.38 mg/liter and a "MATC" <br />of 0.018 to 0.032 mg/liter, resulting in an <br />application factor of .130 to .232. Total and <br />free lead were considered to be the same in <br />soft water. The 18-day TL and "MATC" obtained <br />from the soft water bioassays were 140 g/liter <br />and 6.0 to 11.9 g/liter lead respectively. <br />Computations using the TL 0 and "MATC" values <br />gave a soft water application factor of .0429 <br />to .0850. The maximum acceptable toxicant <br />concentration ("MATC") was determined in both <br />hard and soft water bioassays on the occurrence <br />of abnormal black tails caused by chronic lead <br />exposure. The application factor approach as <br />related to different water qualities was found <br />to be very promising when lead analysis was <br />limited to the free or dissolved metal and <br />54 <br />