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As a part of baseline studies initiated in and near the Nucla East mining area, three <br />• surface water monitoring sites have been est ablished along the West Lateral for obtaining <br /> flow and water quality baseline information (see Tab 15, Hydrologic Monitoring Program). <br /> These sites are SW-N104, SW-N105 and SW-N106 and are located on the West Lateral at points <br /> upstream, midway and downstream of the Nucla East mining area (see Exhibit 7-1). Flory and <br /> water quality data have been collected at these sites since July of 1986, and are <br />presented as Stream Caging Report and Water Quality Reports presented in Appendices 7-5 <br />and 7-9, respectively. <br />Surface water Site SW-N104 is located on the West Lateral just upstream of the <br />northeastern boundary of the Nucla East mining area (see Exhibit 7-1.). Instantaneous <br />discharge measurements are made at SW-N104 in the diversion splitte box, and continuous <br />flow monitoring is conducted at this site via a stilling well and a digital water level <br />recorder located in the channel upstream of the splitte box. Coupled with the continuous <br />stage record, measurement of instantaneous discharge over time will yield a stage versus <br />discharge rating curve for SW-N104 (see Tab 15, Hydrologic Monitoring Program). <br />Figure 7-34 presents a hydrograph of mean daily stage height versus date for SW-N104 <br />• during the 1987 irrigation season. Figure 7-35 presents the preliminary stage-discharge <br />relationship determined for this site based on flow measurements and the stage record <br />obtained since May of 1987. From Figure 7-34, the stage-height in the channel at the <br />recorder varied from a low of less than .3 feet (early October, ditch temporarily turned <br />off) to a high of 2.0 feet. Flow at this upper ditch monitoring site remained relatively <br />constant for long periods throughout the irrigation season, as shown by Figure 7-34 <br />(steady stage of 2.0 feet from 6/l0/87 through 7/6/87). <br />Table 7-53 presents means and ranges of measured instantaneous discharge collected at <br />Sites SW-N104, SW-N105 and SW-N106 for each month. These discharge measurements indicate <br />that irrigation flow varies from a high of 27.6 cfs (August, 1986) to a low of 14.9 cfs <br />(August, 1987). As seen from Figure 7-34, flow occasional recedes to a trickle during the <br />irrigation season, when water in the ditch is temporarily turned off due to routine <br />maintenance or unforeseen problems upstream in the main ditch. <br />Surface water Site SW-N105 is located on the West Lateral at about the midway point <br />between Sites SW-N104 and SW-N106 (see Exhibit 7-1). Instantaneous discharge measurements <br />are conducted at this site in a wooden splitte box. Measured flow values are summarized <br />7-165 Revised 04(11/88 <br />