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Sites SW-N104 and SW-N106. Instantaneous discharge measurements were conducted at this <br />site in a wooden splitte box. Measured flow values are summarized for each month and are <br />included with stream gaging flow reports presented in Attachment 2.04.7-8 (Peabody Appendix 7- <br />5). Measured discharge ranged from 9.2 cfs (August, 1987) up to 14.7 cfs (May, 1987). <br />Surface water Site SW-N 106 was the most-downstream monitoring site located on the West Lateral <br />irrigation ditch. As at SW-N104, instantaneous discharge measurements were made at SW-N106 <br />in the diversion splitte box, and continuous flow monitoring was conducted at this site with a stilling <br />well and recorder also located in the channel upstream of the splitte box. A stage-discharge curve <br />will be more defined over time at this site, as more measurements of instantaneous discharge are <br />obtained and correlated with the continuously recorded stage measurements. Measurements of <br />instantaneous discharge indicated that the ditch delivers irrigation waterto the location of SW-N1 06 <br />for a range of from 7.0 cfs (August, 1987) up to 12.4 cfs (May, 1987). Measured instantaneous <br />discharge values can be found in Peabody Attachment 2.04.7-8 (Peabody Appendix 7-5). The ditch <br />flow recedes almost to zero during periods of 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 diversion <br />locations just upstream of each diversion of irrigation water. Measurements were made using a <br />Marsh-McBirney flow meter for obtaining velocity readings, and a tape measure for determining the <br />cross sectional area of the channel at each measurement location. <br />Sixty two percent of the ditch water was either diverted or lost (due to evapotranspiration and <br />seepage) from the West Lateral splitte flume to Site SW-N1 06. The greatest percentage of lost flow <br />(30 percent) occurred in the reach between the "Benson's Corner" box (13) and SW-N105 (14). <br />Along this reach, a significant portion of the ditch banks are heavily vegetated with willow, wild rose <br />and a variety of grasses that commonly exhibit high rates of transpiration. <br />Interestingly, two reaches showed a gain in discharge. Between Site SW-N104 (5) and the <br />"cemetery" box (8), an increase in flow of 1.5 percent (from 19.4 to 19.7 cfs) was observed. Also, <br />between the "halfway" box (10) and the "bend" box (11), a 12.6 percent increase in flow was <br />observed (from 15.9 cfs to 17.9 cfs). <br />2.04.7-41