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Tony Tennyson <br />Page 2 <br />November 12, 2020 <br />The AHRs should clearly explain the status of sites EFGSC and LWFGSC. These sites are <br />listed in Section 4.05.13 of the Permit Application Package (PAP), which details the water <br />monitoring plan, but there appears to be no mention of them in the 2018 and 2019 AHRs. <br />In past reviews of AHRs, DRMS has asked Colowyo Coal Company to perform the following <br />analyses: <br />• A comparison to CDPHE (Water Quality Control Commission) standards for receiving <br />waters and groundwater down gradient of the mine. <br />• Analyses of spatial trends, comparing upstream data to downstream data (sampling <br />locations above and below the mine) to the extent possible. <br />This was not conducted within the 2018 or 2019 AHRs. Colowyo Coal Company should <br />provide these analyses in future AHRs. The applicable rule related to this requirement is Rule <br />4.05.13(4)(c)(iii). <br />REVIEW OF SURFACE WATER QUALITY DATA <br />The creeks below the Colowyo Mine include (from east to west) Good Spring Creek, Taylor <br />Creek, Wilson Creek, Jubb Creek, Little Collom Gulch and Collom Gulch. <br />There is little or no data for Wilson Creek (monitoring is required in the future if mining begins <br />in the Wilson Creek area), and the data for Lower Collom Gulch reveals no flow (or very little <br />flow). Therefore, the following analyses are focused on Good Spring Creek, Taylor Creek, Jubb <br />Creek, and Collom Gulch. <br />The CDPHE standards used for the analysis of the primary receiving waters below Colowyo <br />were found in the following segments from Regulation 937: <br />• Segment 3e. for Good Spring Creek <br />• Segment 3c. for Taylor Creek (a tributary to Milk Creek) <br />• Segment 3g. for Collom Gulch and Jubb Creek. <br />Table 2 includes standards for several parameters (effective December 31, 2019). These are the <br />parameters of primary interest based on DRMS review of AHRs and Discharge Monitoring <br />Reports, review of USGS data for the Yampa River, and consideration of water use. Because <br />standards are commonly based on the designated use of the water, the Division reviewed the <br />Colorado Division of Water Resources database of water rights to determine if water from <br />Taylor Creek or Good Spring Creek is being used for the designation Water Supply. The search <br />included domestic, household, and municipal uses, and structures included (but was not limited <br />to) reservoirs, wells, and ditches. It was found that there is no apparent use of the water in the <br />creeks and connected alluvia for domestic use or other Water Supply (WS) uses except by <br />