2010-02-01_REPORT - M1983194 (2)

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installation contractor also collects data quarterly; no significant subsidence was detected in 3M- TDR. 5.0 Environmental Monitoring and Protection 5.1 Hydrology Monitoring 5.1.1 Introduction NSI's hydrology monitoring program concentrates on ground water, as there are no perennial streams or springs located on the sodium leases. The USGS stream gauging station-monitoring program is conducted, with NSI support, to provide regional stream flow data. The hydrology-monitoring plan is designed to determine impacts of NSI's solution mining operations on underground sources of drinking water, as designated by the US EPA. Figure 5.1 illustrates the location of existing monitor wells. A thorough discussion of historical water monitoring data was presented in previous Annual Reports and will not be repeated in this report. Through 2009, dewatering did not affect the Perched aquifer or the nearby springs fed by this aquifer. The A-Groove aquifers were affected locally (WL by pumpage from water well). 5.1.2 Stream Gauging Stations NSI continues to contract with the USGS to monitor surface water for water quality and quantity. Monitoring was performed upstream and downstream of the mining operation on Yellow Creek and Piceance Creek at four existing stations with extensive historical data. Funding for the USGS stations was shared with one of the other nahcolite projects (Solvay) in the area. Data for the 2008 water year (October 2007-September 2008) was published the following year in 2009 by the USGS. The USGS water data is available to the public from the USGS web site at http://co.water.usgs.gov. Table 5.1 is a summary of key 2008 data for the NSI site. A review of USGS stream water quality data indicates no significant change in stream water quality through 2008. Therefore, no effect on stream water quality was noted from the NSI operation. Table 5.1 Historical vs Current 2008 Data Specific conductance microsiemens/centimeter 251 C. Tem °c. Discharge P of R* Discharge 2008 WY** Total DischargeP of R Total Discharge 2008 P of R 2008WY P of R 2008 WY P of R 2008 WY Station cfs cfs ac ft/ r ac ftl r Max Max Min Min Max Max 6200 29.1 (40 yrs) 27.9 21,060 20,270 2,920 1,460 398 943 28 17.2 6222 36.140 s) 36.2 26,130 26,290 10,000 1,950 460 1,170 32 13.1 6242 1.93 (31 s) 1.28 1,400 931 3,000 1,350 271 11280 29 14.2 6255 3.01 (32 s) 1.11 2,180 804 5,790 3,830 457 3,440 35 19.4 2009 Annual Report 8 of 33