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for each month in Table 7-53 and are included with stream gaging flow reports presented in <br />• Appendix 7-5. Measured discharge has ranged from 9.2 cfs (August, 1987) up to 14.7 cfs <br />(May, 1987). <br />Surface water Site SW-N106 is the most-downstream monitoring site located on the West <br />Lateral irrigation ditch (see Exhibit 7-1). As at SW-N104, instantaneous discharge <br />measurements are made at SW-N106 in the diversion splitte box, and Continuous flow <br />monitoring is conducted at this site with a stilling well and recorder also located in the <br />channel upstream of the splitte box. A stage-discharge curve will be more defined over <br />time at this site, as more measurements of instantaneous discharge are obtained and <br />correlated with the continuously recorded stage measurements (see Tab 15, Hydrologic <br />Monitoring Program). <br />Figure 7-36 presents a hydrograph of mean daily stage height versus date for Site SW-N106 <br />during the 1987 irrigation season. Figure 7-37 presents the preliminary stage versus <br />discharge relationship determined for this site based on flow measurements and the stage <br />record obtained since May of 1987. From Figure 7-36, the stage height in the channel at <br />• the recorder varied from a high of 1.6 feet to a low of less than .2 feet (early October, <br />ditch temporarily turned off). Flow at this lower ditch monitoring site remained <br />relatively constant for long periods throughout the irrigation season, as shown on Figure <br />7-36 (steady stage of 1.40 feet from 7/1/87 through 7/24/87). <br />Measurements of instantaneous discharge indicate that the ditch delivers irrigation water <br />to the location of SW-N106 for a range of from 7.0 cfs (August, 1987) up to 12.4 cfs (May, <br />1987, see Table 7-53). Measured instantaneous discharge values can be found in Appendix <br />7-5. As indicated by Figure 7-36, the ditch flow recedes almost to zero during periods of <br />ditch maintenance. <br />A "gain-loss" study was performed on the West Lateral irrigation ditch on July 7 of 1986. <br />Measurements of instantaneous discharge were collected along the ditch course at select <br />diversion locations just upstream of each diversion of irrigation water. Measurements <br />were made using a Marsh-MCBirney flow meter for obtaining velocity readings, and a tape <br />measure for determining the cross sectional area of the channel at each measurement <br />location. <br />• Table 7-54 presents the results of the study performed at the selected "splitte boxes" <br />7-170 Revised 04/11/88 <br />