1986-12-31_REPORT - C1981008 (3)

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Despite these seasonal fluctuations and despite the fact that this site is located downgradient of mining, the quality of water at this site has remained essentially unchanged with respect to all of the reported parameters including TDS (see Table 3) since monitoring began in October 1979. Comparison of the 1980-81 data, to the 1985-86 data presented in Table 8 substantiates this conclusion. Table 9 which compares October 1979 data with that of October 1985 data also substantiates this -conclusion. In fact, even though flow was substantially lower in 1985, 618 gpm in 1985 versus 1346 gpm in 1979, TDS concentration was actually slightly lower in 1985 than in 1979. With respect to Colorado Department of Health (DOH) receiving stream standards (DOH, 1983) , Tuttle Draw lies within Stream Segment 12 of Region 10 of the San Miguel River (see Table 10). Stream Segment 12 is defined as follows: All tributaries to the San Miguel River from a point - immediately below the confluence of Leopard Creek to the Dolores River with the exceptions listed in Segments 9, 10 and 11. The listed exceptions do not apply to Tuttle Draw. As a result, the numeric standards which apply to this segment are those which only pertain to the physical and biological parameters. Specifically, these standards are dissolved oxygen (DO) , pH and fecal ccliform with limits of 5.0 mg/l , 6.5-9.0 units, and 2000/100 ml , respectively. Fecal coliform and DO are not analyzed as part of the approved monitoring program and PH values have always ranged between 7.4 and 8.2 for the period of record. Besides receiving stream standards, the DOH has recently drafted a set of water quality standards for the purpose of protecting ground water quality with respect to agricultural use (DOH, 1986; Table 11) . Although these ground water standards have not yet been approved by the DOH, they will be used in this 29