2018-07-02_PERMIT FILE - C2010089A (19)

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summarized in Table 2.04.7-5, which also includes data from monitoring at the old Nucla Mine. The data in this table indicates that the average annual mean surface water flow onto the NHN permit area is on the order of about 3,949 acre-feet (ac -ft) and the flow out of the NHN permit area is about 2,742 ac -ft per year. The difference is about 1,207 ac -ft per year. Some of this difference is the result of evapotranspiration which as discussed previously is on the order of 2.1 ac -ft per acre per year. The permit area including the haulage corridor is about 320 acres. Evapotranspiration could account for about 672 ac -ft per year. Therefore, about 535 ac -ft is still not accounted for. Flow in Nygren Draw and seepage from the toe of the old mine backfill accounts for an additional 243 ac -ft. The remaining 292 ac -ft either leaves the permit area as higher than estimated evapotranspiration or infiltrates into the bedrock zones. The baseline water level measurements demonstrate the rapid recharge of groundwater levels in response to seasonal irrigation. Groundwater migrates through the overbruden, coal and underburden zones downdip to the southwest toward the bedrock outcrop, (see Map 2.04.5-1). Total migration of groundwater from NHN through the bedrock zones at the rate of only 3.3 gpm would account for the entire remaining 292 ac -ft. From historical data (see New Horizon 1 Area Permit) the annual flow from the backfill and irrigation runoff water in Nygren Draw out of NPDES pond 001 is about 243 ac -ft. Subtracting the flow in Nygren Draw at SW -N06 results in a net annual gain of just 44 ac -ft. This equates to a continuous flow rate of about 0.001 cfs or > 0.5gpm. The total flow from NPDES Pond 001 (243 ac -ft) explains some of the gain in the Tuttle Draw flow from SW -N1 to SW -N3. The 1986 to 1987 monitoring data from SW -N1, SW -N3, SW -N6, SW -N7, and NPDES 001 are included in Appendix 2.04.7-2 of this application. The out of permit flow of Meehan and Glasier Draws into the upper reaches of Coal Creek Canyon is about 811 ac -ft per year or an average of about 1.12 cfs. Downstream users to the 2nd Park ditch system use about three times more water than the permit area and upstream users suggesting that annual flow into Coal Creek Canyon as the result of irrigation is on the order of 3,200 ac -ft per year or an average of about 4.4 cfs. The flow in the lower reach of Coal Canyon (site CSS) during March 2011 (non -irrigation season) was measured at 1.296 cfs. Surface Water Ouality Baseline water samples from the surface water monitoring sites were collected quarterly when a site was experiencing flow (see Map 2.04.7-1). The 2nd Park Lateral flowed from April 23, 2009 through October 5, 2009. Out flow monitor sites on (SW -N202, SW - 203) Meehan and Glasier Draws flowed throughout the year, while inflow sites on the same two draws showed periods of being dry. This indicates the seepage of irrigation water maintains flow in the lower reaches (within the permit area) of these two draws. Water quality data from the surface water monitoring sites at the NHN permit area are contained in Appendix 2.04.7-2 of this permit application. Glasier Draw and Meehan Draw provide about 811 ac -ft of flow to the upper reaches of Coal Canyon this flow has a weighted average quality of about 1320 mg/l TDS. The baseline water quality analyses from the new sites indicate that the water flowing into the permit area is better than the water flowing out of the permit area. This indicates a natural degradation Section 2.04.7 Page 22 April 2016 (PR -01)