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damage. In 2008, readings were again taken and data was gathered from cables two and three. In <br />addition to the monthly NSI readings, the installation contractor also collects data annually, (Figure <br />4.4); no significant subsidence was detected in 3M-TDR. <br />5.0 Environmental Monitoring and Protection <br />5.1 Hydrology Monitoring <br />5.1.1 Introduction <br />NSI's hydrology monitoring program concentrates on ground water, as there are no perennial <br />streams or springs located on the sodium leases. The USGS stream gauging station-monitoring <br />program is conducted, with NSI support, to provide regional stream flow data. <br />The hydrology monitoring plan is designed to determine impacts of NSI's solution mining <br />operations on underground sources of drinking water, as designated by the US EPA. Figure 5.1 <br />illustrates the location of existing monitor wells. A thorough discussion of historical water <br />monitoring data was presented in previous Annual Reports and will not be repeated in this report. <br />Through 2008, dewatering did not affect the Perched aquifer or the nearby springs fed by this <br />aquifer. The A and B-Groove aquifers were affected locally (WL by pumpage from water well). <br />5.1.2 Stream Gauging Stations <br />NSI continues to contract with the USGS to monitor surface water for water quality and quantity. <br />Monitoring was performed upstream and downstream of the mining operation on Yellow Creek <br />and Piceance Creek at four existing stations with extensive historical data. Funding for the USGS <br />stations was shared with one of the other nahcolite projects (Solvay) in the area. Data for the <br />2007 water year (October 2006-September 2007) was published the following year in 2008 by <br />the USGS. The USGS water data is available to the public from the USGS web site at <br />http://co.water.usgs.gov. Table 5.1 is a summary of key 2007 data for the NSI site. <br />A review of USGS stream water quality data indicates no significant change in stream water quality <br />through 2007. Therefore, no effect on stream water quality was noted from the NSI operation. <br />Table 5.1 <br />Dis. Dis. <br />P of R* 2007WY** <br />Station cfs cfs <br />6200 <br />Piceance 1 <br />29 <br />Creek below . <br />Ryan Gulch (40 yrS) 15.2 <br />6222 <br />Piceance 140 <br />36 <br />Creek at . <br />White River yrs) 17.8 <br />6242 Corral 1 <br />93 <br />Gulch near . <br />Rangely (31 yrs) 0.45 <br />6255 Yellow 01 <br />3 <br />Creek near . <br />White River (32 yrs) 1.19 <br />2008 Annual Report <br />Historical vs Current 2007 Data <br />Specific conductance <br />Total Total (microsiemens/centimeter A 250 <br />Discharge Discharge <br />P of R 2007 <br />ac ft/vr ac f r <br />21,060 20,275 <br />26,130 26,294 <br />1,400 931 <br />P of R 2007 WY P of R <br />Max Max min <br />2,920 1,700 <br />10,000 3,500 <br />3,000 1,280 <br />2,180 804 <br />8 of 28 <br />2007 <br />WY <br />Min <br />398 1,260 <br />460 1,640 <br />271 1,210 <br />5,790 4,230 457 3,910 <br />2007 <br />PofR WY <br />Max Max <br />28 15.9 <br />32 22.8 <br />29 18.7 <br />35 22.3