2020-06-04_PERMIT FILE - C1981008A (2)

Home Browse Search

Flow correlated with TDS fairly well at some sites, but the variability of the correlation results at all sites indicated that the relationship between these two parameters was not strong. For instance, during periods of no irrigation, flow correlated strongly with TDS (r2 >.75) at sites SW -N103 and at SW -N7. However, the period of record for the data sets analyzed for these two sites was less than two years. During the irrigation seasons, flow correlated well with TDS (r2 >.75) at Sites SW -N102 and SW -N105. Again, data analyzed for both these sites were limited (July, 1986 through December, 1987). Considering the analyses performed on the large data sets for both seasons collected at both SW -N1 and SW -N3 (1980 through 1987), it was concluded that flow had little correlation with TDS. Finally, TSS did not correlated with TDS. A negative value for the correlation coefficient (r2 ) that approaches 1.0 (>.750) would indicate that TDS is inversely related to TSS. For each site during both seasons, the correlation coefficient determined using the simple regression and correlation technique were not negative as expected, never exceeded .600, and ranged from .007 (SW -NI, irrigation season) up to .593 (SW -N6, non -irrigation season). Based on the aforementioned results, it was concluded that discharge (flow) had no relationship with TSS. It should be noted that TSS values were determined by an outside laboratory using a small yet proportionally divided portion of each water sample taken at each site. However, considering the magnitudes of TSS determined for sites at the New Horizon 2 mining area (10 to 100 mg/1), the laboratory analyses were well within reason. Discharge probably had some influence (relationship) on TDS concentration, but the regression analyses for all sites during both seasons indicated that the relationship was inconsistent and still inconclusive. Finally, there appeared to be no relationship between TSS and TDS. TSS values have only occasionally exceeded 500 mg/l at any monitored site, likely resulting in very few instances where the suspended solids in the flow influence TDS by adsorbing ions and reducing the dissolved chemical load. Surface Water Suitability This section discusses the suitability, present use and potential use of surface water monitored at stream sites at the New Horizon 2 mining area. The suitability of surface water is discussed by comparing historical water quality data for each site with the most stringent state or federal standards established for: 1) drinking water; 2) agricultural water; and 3) livestock drinking water. Also, surface water is discussed in relation to receiving stream standards applicable to the San Miguel River as adopted by the Colorado Department of Health (CDOH, 1983 revised, 1986). Surface water use, both present and potential, is described in relation to each water standard category. Surface water at all stream sites, except SW -N104, SW -N105, and SW -N106, was found to be unsuitable for drinking water because of sulfate and manganese excedences. Lead and iron standards were exceeded at four of the sites, while pH and nitrogen -ammonia (NH3) were exceeded at three and one stream monitoring site, respectively. Interestingly, the three sites located on the West Lateral irrigation ditch all fell within the drinking water standards. Historically and presently, irrigation water delivered by the West Lateral has been and currently is used by local residents as a source of drinking water. Sulfate and manganese are commonly exceeded at all other stream sites established in tributaries of and along both Calamity and Tuttle Draws. With regard to the agricultural standards, only manganese was exceeded at all surface water monitoring sites, with the exception of the West Lateral irrigation ditch sites (SW -N104, SW -N105, SW -N106). Five Page 2.04.7-26 March 2017 (TR -77)