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<br />002442 <br /> <br />Ecology <br /> <br />In addition to the water-qual ity models described previously, involving <br />biological and chemical processes, certain other possible ecolog'ical impacts <br />of energy development might be modeled and included in the analysis. It Is <br />not possible to comprehensively model the entire ecosystem of the Yampa River <br />basin in light of time and fiscal constraints of the project, as well as the <br />state-of-the-art in ecological modeling. However, certain important ecologi- <br />, cal impacts can be seen to be closely linked to specific aspects of the devel- <br />opment process and, for this reason, demand attention in the analysis, <br /> <br />The model ing and investigatIve techniques described in this section are <br />proposed as part of the residuals-management analysis in coordination with the <br />basin assessment. Uncer.tainties regarding timely and successful completion of <br />these components for inclusion in the basIn assessment should be kept In mind, <br /> <br />Recl amat ion <br /> <br />One ecological process of obvious interest is revegetation of reclaimed <br />mining areas. As a part of the residuals-management analysis, a simulation <br />model of the reclamation process may be developed and appl ied to specific min- <br />ing sites in the Yampa River basin. One relationship of major importance is <br />the manner in which topsoil application and the choice of plant species affect <br />the sediment yields from reclaimed land. <br /> <br />Mining in the Yampa River basin, to a large extent, represents an alter- <br />nate land use to ranching, farming, and timber harvesting, Thus"cropland and <br />range management become important activities in the regional analysis. More- <br />over, revegetation programs currently underway at mining areas in the region <br />are oriented towards establ ishing grazing land, so that range management is <br />ultimately an important factor in the reclamation process, Some simple models <br />currently exist relating grazing intensity to density of plant cover which, in <br />turn, becomes a term in sediment-yield equations (U.S. Department of Agricul- <br />ture, 1961; Roth and others, 1974; Stoddart and others, 1975), These models <br />wi 1'1 be eva 1 uated for poss i ble appl icationto the bas In assessment. <br /> <br />Sport Fi sher i es <br /> <br />One likely result of possible increased sediment loads in the Yampa River <br />and Its tributaries would be a reduction in fish survival and reproduction-- <br />particularly ,in the case of trout populations which represent an extremely im- <br />portant recreational resource in the bas in. Suspended sol ids at 'even moderate <br />concentrations, in the order of 100 mg/l (milligrams per litre) or greater, <br />are known to lead directly to mortal ity of adult trout, as well as to the de- <br />struction of gravel-spawning areas (Alabaster, 1972), A model of trout sur- 'I <br />vival and spawning success is proposed for development that will accept input <br />data on sediment concentrations generated by the sediment-transport model. <br /> <br />A considerable amount of data on trout reproduction and growth has been <br />collected in experiments and field studies of brook, brown, and rainbow trout <br />populations in Colorado, Of particular value in the proposed model ing effort <br />will be the large number of studies completed by Klein (1974) of the Colorado <br />Division of Wi ldl ife on trout populations in basins neighboring the Yampa. <br /> <br />24 <br />