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• Sage Creek Pzemining: <br />Sage Creek <br />Sage Creek Postmining: <br />Sage Creek <br />Sage Creek <br />L = 0.9149 x 629 x 0.0027 = 1.554 tons(day <br />DSC = 1.554 + 0.034 = 641 mg/1 (1.9% TDS increase) <br />(1.814+1 + 0.0055) x 0.00176 <br />L = 0.9176 x 641 x 0.0027 = 1.588 tons/day 12.2%. tonnage <br />increase) <br />The magnitude of the cumulative TDS increase in the Dry Creek st reamflow up to the SGS <br />monitoring location is approximately 114 percent. The range of the TDS increase extends <br />Erom the confluence of Hubberson and Watering Trough Gulches to [he reach of Dry Creek in <br />the northwest corner of Section 34 (upstream of the fields irrigated from Temple Reservoir <br />pl). At this point, the natural TDS levels in Dry Creek begin increasing. The magnitude <br />of the TDS and chemical tonnage load increases from spoil discharges along this reach of <br />Dry Creek are 44 percent over background. Background TDS levels along Dry Creek were <br />measured indirectly by a series of same day field parameter measurements taken at select <br />points in Dry Creek from Monitor Site FG1 [o near the rodeo grounds in the Town of Hayden <br />• on October 12, 1990 (Table 17-20) . The 44 percent TDS and chemical load increase over <br />background extends for approximately 1 mile downstream. At the southwest corner of <br />Section 22, where the county road crosses Dry Creek, the conductivity levels and <br />calculated TDS levels are so high (3,567 mg/1 TDS) that the spoil discharge influences <br />would be diluting the Dry Creek water quality rather than degrading it Erom this point on. <br />The source of the natural salt loading to Dry Creek is principally seepage from dry land <br />farming [hat extends from the hillslopes at the base of the mountains to Rayden. The <br />dryland farming saline seep problem has been well documented in the literature. Two such <br />articles are Raloff (1984) and Alberta Dryland Salinity Committee (19751. Dryland <br />salinity problems typically occur in regions where annual precipitation is between 14 to <br />20 inches. The mean annual precipitation for Hayden between 1951-1980 was 15.9 inches. <br />The principal cause of the dryland salinity is the movement of excess moisture through the <br />soil to shallow, low permeability zones where the water moves laterally down slope picking <br />up salts. Excess salts are available in the soils being dryland Earmed along Dry Creek <br />because the parent material from which these soils were derived is marine shales. In the <br />low lying discharge areas along [he drainages and tributaries draining these fields, the <br />• water is brought to the surface as seeps or by capillary action, evaporates and leaves an <br />accumulation of salt. These salt accumulations are then available Eor dissolution and <br />transport to the principal drainages. <br />51 Revised 03101 <br />