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b. Surface Water <br />The probable hydrologic consequences resulting from the mining activities to <br />surface water at the Hamilton Mine permit area will result from alterations to runoff <br />characteristics, surface configuration, and water quality. Total dissolved solids <br />(TDS) for Naturita Creek, vary from 900 to 1,750 mg/l, and are much higher than <br />for the San Miguel River, which has a weighted average TDS of 316 mg/l. <br />According to data provided by Honeywood Coal Company, sulfates vary from 500 <br />to 963 mg/1 in Naturita Creek water, whereas San Miguel River water generally has <br />less than 100 mg/1. Levels of calcium, magnesium and potassium are also higher in <br />Naturita Creek than in the San Miguel River. Naturita Creek is suitable for <br />livestock use. To date, mining activities have not contributed to changes in water <br />quality parameters of either of these streams since there has been no recorded flows <br />from the minesite. Total suspended solids (TSS) is still expected to decrease as a <br />result of interception of water by sediment ponds. Total salt loading is still expected <br />to increase somewhat due to exposure of materials not previously in contact with <br />surface water, breakup of overburden by mining activities and concentration due to <br />evaporation of water during retention in sediment ponds. <br />Samples taken during runoff resulting from 1988 snowmelt and storm events along <br />Long, Center, Section 33 and Hamilton (referred to as Broad Creek in the permit <br />application) Creeks show a variability in TDS from 5,080 mg/1 on upper Hamilton <br />Creek following a storm, to 110 mg/l on Upper Center Creek following snowmelt. <br />Sulfates varied from 3,680 mg/l on Upper Hamilton Creek during the same storm <br />event to 110 mg/l on Upper Center Creek during the same snowmelt runoff <br />sampling. No runoff from the disturbed area is expected during dry periods or <br />during minor precipitation and snowmelt events, due to high surface infiltration <br />rates, evaporation and interception of minor runoff by sediment ponds. <br />There is very little contribution of flow to Naturita Creek from the permit area <br />drainage. While flow in Naturita Creek does increase from above the permit area to <br />its confluence with the San Miguel, that increase appears to be due primarily to <br />irrigation return flow and minor subsurface flow. Except during significant <br />snowmelt and storm events, there appears to be insufficient runoff to allow flow in <br />the draws across the proposed permit area. In those rare instances where runoff does <br />develop, little water actually reaches Naturita Creek. For example, an October <br />2-3, 1988 storm event contributed to flow in all draws across the permit area, yet <br />there was no flow in lower Hamilton Creek at its confluence with Naturita Creek, <br />below where it received water from the proposed permit area. This indicates that <br />either the flow event was extremely short-lived, or that flow infiltrated prior to <br />reaching the confluence with Naturita Creek. <br />Except during infrequent high precipitation events, surface runoff within the permit <br />area is insufficient to routinely mobilize constituents and transport them to receiving <br />waters. During an average year, runoff from the site is calculated to contribute <br />between 13 and 69 tons/day dissolved constituents as TDS which may not, however, <br />15