2014-01-14_REPORT - C1981019 (3)

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U_�� TRI -STATE GENERATION AND TRANSMISSION ASSOCIATION, INC. HEADQUARTERS: RO BOX 33695 DENVER, COLORADO 80233 -0695 303 - 452 -6111 January 8, 2014 'EcEIvED Mr. Rob Zuber 4 2014 Environmental Protection Specialist A� Colorado Division of Reclamation, Mining and Safety DNISION OF F.ECIAMATI�N Department of Natural Resources MINING AND SAFEV 1313 Sherman Street, Room 215 Denver, CO 80203 RE: Colowyo Coal Company L.P., Mine Permit C-81-019,2012 Annual Hydrology Report Responses Dear Mr. Zuber: Colowyo Coal Company L.P. ( Colowyo) received your 2012 Annual Hydrology Report (AHR) comment letter, dated September 30, 2013 (original comments in italics), and has the following responses: DRMS Item 1: In future AHRs, please explain gaps in data, including exhibits that have no data for certain drainages because of no flow. Response: Beginning with the 2013 AHR, Colowyo will provide additional information to describe the gaps in the data as requested. DRMS Item 2: A written interpretation of the data is requested by the Division. per Rule 4.05.13(4)(c)(iii). This was agreed upon during review of'the 2009 AHR This should include, but not be limited to, a discussion on relatively high values of parameters collected in 2012, increases in parameters at particular monitoring locations (long term trends), and potential impacts on receiving waters, namely Good Spring Creek and Taylor Creek especially as discussed in the PHC of the Permit Application Package. Response: As part of the 2013 AHR and moving forward, Colowyo will include an interpretation of the data in relation to the Probable Hydrologic Consequences section of the PAP as requested. DRMS Item 3: The Division has the following observations regarding surface water data (no direct response is required from Colowyo although these comments are related to comment number 2 above): • Per the R`'values for surface water shown in the graphs in the exhibits, there are no significant long -term trends (increasing or decreasing) in the data. • For the reporting year of the 2012 AHR (which is the 2012 calendar year), concentrations of some parameters reached the maximum values of the entire recording period. • For the UWFGSC site, these parameters include sulfate (339 mg11) and magnesium (101 mg 11). The period of record for water quality data collection at this site is 2007 --present, • For the LGSC site, a maximum value for sodium (215 mg /1) was recorded in August 2012. Other high values of sodium were recorded in May 2012 and October 2012 at this site, indicating a possible trend that should be monitored closely in the fiiture. The period of record for this site extends back to 1983. Response: No response required. ANt-004( OPPORrUNITY /AFFIRIbIATIVEACTiOP/EiuIPLOYER A Touchstone Energy' Cooperarn'e .5 CRAIG STATION ESCALANTE STATION NUCLA STATION P.O. BOX 1307 P.O. BOX 577 P.O. BOX 698 CRAIG, CO 81626 -1307 PREWITT. NM 87045 NUCLA, CO 81424.0698 970 - 824-4411 505- 972 -5200 970- 864 -7316