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confluence with Foidel Creek is in the narrows located approximately <br />3500 feet south of the confluence. Meanders above this point would preclude <br />ditches upstream of this point. From the narrows to the confluence with Trout <br />Creek there is approximately 33 feet of head drop over a potential ditch path <br />length of 5400 feet. Water wquld have to "raised" approximately 5 feet <br />because Middle Creek is incised. Using a ditch with a gradient of 5 feet per <br />thousand and the natural ground surface gradient of 6 feet per thousand would <br />require 5000 feet of ditch to "raise" the water 5 feet. Therefore the first <br />irrigation would begin at approximately the mouth of Middle Creek and in the <br />area that is potentially irrigatable from the larger Trout Creek. <br /> The maximum impact of the mine discharges on the irrigation water quality to <br />'~ waters in Trout Creek below the confluence area is to increase the dissolved <br />~1ti""~ solids concentration by approximately 12% (Exhibit C). The dissolved solids <br /> would increase from 750 to 837 mg/l. This analysis is based upon water <br />-^ ~~~ quality and flow data for station 69 and spoil spring flow estimates. <br />1 <br />Twentymile Coal Company (TCC) has collected additional information in order <br />(~ <br />i"~ ~ to further characterize the alluvial valley floor regions associated with <br />ition <br />ere <br />F <br />l <br />Middl <br />T <br />h C <br />k <br />ti <br />d co <br />id <br />t <br />d Fi <br />V <br />t <br />~ , <br />rou <br />ege <br />a <br />ve cover an <br />mpos <br />w <br />o <br />e <br />e, <br />an <br />s <br />ree <br />s. <br />_ ,1~ determined from information obtained during the 1984 and 1986 field seasons. <br />~`7 ~ The location of the transects conducted during the 1986 field season are shown <br /> on Map 36, Salt Loading Study. Fifty meter transects were randomly located and <br /> ten-point frames were placed at five meter intervals to yield 100 hits per <br /> transect. Each transect was treated as separate datum for the purposes of <br /> determining vegetative cover and composition. <br />'"~ <br />5 ~r- Production data were obtained for Pastures 2 and 11. Individual species <br />2 \ <br />~~~ <br />~ contained within the volumetric projection of quarter meter plots were <br />ry~ clipped, oven-dried, and weighed to the nearest .1 gram. Data collected from <br />cc ~~"'4" three plots for each transect were averaged to describe a specific *.ransect. <br />bn k~~ <br />/ The vegetative cover and production of the two pastures are denoted on <br />~ ~ Table 1, Pasture Two Vegetative Cover and Production and Table 2, Pasture <br />` <br />r1~ <br />~°~ Eleven Vegetative Cover and Production. <br />(~ <br /> • <br />2 <br />Revised 10/1/86 <br />