2020-03-24_PERMIT FILE - C1981019A (5)

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RULE 2 PERMITS R,V44, ,\V .'dittRMrtbt.k.4a.M\v. .3 "heT\j .. `TS R.K�\\M. •y. cfs for Taylor Creek to 37 cfs for Wilson Creek. Peak flow estimates are calculated at 120 cfs for Taylor Creek, 190 cfs for Wilson Creek and 270 cfs for Goodspring Creek. Tables 2.04.7-14, 2.04.7-15 and 2.04.7-16 present the flow estimates for Taylor Creek, Wilson Creek and Goodspring Creek, respectively. These data give the 24-hour and 7-day high flows for return periods of 1, 10, 50 and 100-years and the probability of these flow values being exceeded. Local factors which minimally affect streamflow in the area are several small, man-made impoundments. These reservoirs have a capacity of less than 1-AF and are used to provide normal water supplies for livestock. These structures do not significantly affect the streamflows in the vicinity of the mine. Surface Water Quality General Area Surface water quality in the general area is affected at the baseline level by irrigation, farming, existing roads,previous underground mining and,potentially,the wildlife in the surrounding area. The surface water quality in the general area is extremely variable and is a function of the climate patterns (see Section 2.04.8 for climatological information) and geology (see Section 2.04.6 for geological information) as well as past human-caused disturbances. Water quality constituents show seasonal and monthly fluctuations and yearly fluctuations due to all of these factors. Permit Area Water quality sampling programs have been conducted in and around the mine area since 1974 by various teams of investigators. The BIM EMRIA program set up sampling stations on Taylor, Wilson and Goodspring Creeks to collect continuous data for a great number of quality constituents. Colowyo and its consultants have sampled these same stations as well as a separate series of stations from 1974 to present. All of these stations are located on Map 32 and a table of the site numbers and descriptions is presented earlier in the discussion Occurrence of Surface Water, Table 2.04.7-7. Surface water in the area can be characterized as extremely hard containing an abundance of dissolved solids and variable levels of other constituents. Data collected by Colowyo in 1974 and 1975 showed that total hardness exceeded 300 mg/1 as CaCO3 for all samples. Positively charged cations were predominately calcium and magnesium with sodium present in lesser quantities. Potassium was present only in very low quantities and heavy metals were nearly absent.Negatively charged anions were comprised primarily of bicarbonate and sulfate. Chloride was present in low levels. Fluoride,carbonate,nitrate and silica were present in very low levels or were nearly absent. The data for the period 1974-1975 collected by Colowyo for the major ion concentrations, turbidity, dissolved solids, iron, and pH for the seven sampling locations along Wilson Creek, Taylor Creek and Goodspring Creek are presented in Tables 2.04.7-17, 2.04.7-18 and 2.04.7-19. For all constituents except chloride, the concentrations varied only slightly among the stations during any OM inunth. Also coy c ntiations above and below tic niinc were not appicciably Rule 2 Permits 2.04-25 Revision Date: 12/20/19 Revision No.: TR-135