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RULE 2 PERMITS <br />Surface Water <br />General Area <br />The water quality in the general area is extremely variable, resulting from precipitation generated runoff <br />and minor groundwater seepage. No adverse impacts are predicted for water quality in the general area as <br />a result of mining operations. Primary constituents of concern for water quality in the general area are <br />TSS, TDS and its related parameter specific conductivity. <br />Data reported by Parker and Turk (1981), Skogerboe and others (1979) and Bishop and others (1982) all <br />reflect the variability in these parameters. In fact, seasonal, flow-related, and runoff-related variability is <br />extreme for all of these parameters. TSS in the Yampa River basin are high due to the seasonal <br />precipitation, soil and vegetation types, and drainage slopes. Many aquatic organisms have adapted to <br />these periodic, high levels of TSS in the Yampa River and include the Colorado Squawfish <br />(Ptychocheilus lucius), humpback chub (Gila cypha), humpback sucker (Xyrauchen texanus), and <br />bonytail chub (Gila elegans), all native species. Historically, the lower sections of the Yampa River have <br />been the habitat areas of these organisms. Recent fish capture data of the U. S. Fish and Wildlife Service <br />show some of these organisms to be present in the Lily Park pool downstream of the mine areas (USFWS <br />1977). The naturally occurring TSS loads generated in the general area will continue to occur <br />undisturbed. <br />TDS and specific conductivity values are also extremely variable by season and will not be impacted by <br />the Colowyo Mine. Data presented by Bishop and others (1982), previously discussed, show that the <br />Colowyo Mine will have no effect on these parameters in the short or long term. In fact, the Colowyo <br />Mine was left out of the analysis because of the anticipated no effect. <br />Permit Area <br />No significant effect on surface water quality in or adjacent to the permit area will occur as a result of <br />mining operations. Water quality in and adjacent to the mining area is highly variable with primary <br />constituents of concern reflecting seasonal and precipitation related trends. <br />TSS values show extreme fluctuations at Taylor, Wilson and Goodspring Creeks. Sediment yield rates for <br />the mine area using the Universal Soil Loss Equation and a rainfall factor of 30.0 averaged 3.17 <br />tons/acre/year for the mine permit area. This average was broken down into the component parts of <br />undisturbed land and land being mined or in a stage of reclamation. The total acreage contributing to <br />these estimates is 4118 acres of which a maximum of 1000 acres will be disturbed at any one time. The <br />estimated yield of 3.5 tons/acre/year for the disturbed land is much less than the 5.0 tons/acre/year <br />maximum acceptable topsoil loss from agriculturally productive land calculated by the U. S. Department <br />of Agriculture Soil Conservation Service (SCS). The design limit was based on continued productivity of <br />topsoils for crop production. <br />TSS will be controlled in runoff from the permit area by detention ponds which have been designed to <br />retain runoff from the 10-year, 24-hour event. <br />Water is periodically released from the sediment ponds when TSS and other parameters meet the <br />discharge standards for the Colowyo NPDES Permit. <br />TDS concentrations are expected to remain within the ranges of values known to exist presently. The data <br />presented and discussed earlier shows tremendous fluctuations. TDS is inversely related to flow. That is, <br />as the flow decreases the TDS values increase as a result of a larger proportion of groundwater seepage <br />Rule 2 Permits 2.04.7-32 Revision Date: 6/23/08 <br />Revision No.: MR-91