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i The June sample had the lowest concentration of total dissolved solids <br />(TDS) while the August sample had the highest. The graphs show that <br />the water types are the basically same. There is an increase in <br />sulphate at the downstream site. This increase can be attributed to <br />the coal and shale formations which contain higher levels of sulphate. <br />In addition, a limited amount Of sulphate comes from the mine water <br />discharge. Overall, water quality remains the same from season to <br />season and from station to station, Mining activities have limited <br />impact on water type. <br />North Thompson Creek is part of the Upper Colorado River Basin and <br />North Platte River, Planning Region 12. The Colorado Department of <br />Health (CDOH), Water Quality Control Commission classifies North <br />Thompson Creek as Class 2 Recreation, a Class 1 Cold Water Aquatic <br />Life, a Water Supply, and Agriculture, effective June 9, 1980. When <br />North Thompson's Creek water quality analysis is compared to the above <br />standards, all parameters, in all categories, are under the standards <br />• except copper. It should be noted that the Snowmass' analyses are on <br />a dissolved basis whereas, part of the CDOH standards are on a total <br />basis. No EPA drinking water standards were exceeded. <br />Table 3.6.1-14 lists the observed copper concentration at both sites <br />and denotes which ones exceed the CDOH standards. Figure 3.6.1.2-4 <br />present graphs of these values. <br /> <br />3-77 <br />