Laserfiche WebLink
<br />...t <br />1:'- <br /><:J:) <br /> <br />,,,,;.., <br /> <br />o <br />C) <br /> <br />Seepage <br /> <br />Canal seepage tests have been conducted on numerous portions of the <br /> <br />distribution systems in the valley, the results of which are shown in Tables <br /> <br />2 and 3 (see map 1295-417-808, page 45, for site locations). <br /> <br />During the 1977 tests, numerous small seeps and drains adjacent to the <br /> <br />Government Highline Canal, which had been dry since the end of the irrigation <br /> <br />season, began flowing coincidentally with the filling of the ponded sections. <br /> <br />It was noted that water levels in numerous adjacent observation wells re- <br /> <br />sponded immediately to the filling of the canal. During August 1977, summer <br /> <br />storms contributed large sediment inflows to the Government Highline Canal of <br /> <br />such magnitude that a large fishkill (suckers mostly) took place in the <br /> <br />canal. The effect of this sedimentation would tend to decrease seepage rates <br /> <br />due to sealing action by filling pore spaces. Under postproject operation <br /> <br />and with improved cross drainage, the entry of sediments to the canal should <br /> <br />be substantially reduced. <br /> <br />Inflow,-outflow measurements were made twice during the summer of 1977 on <br /> <br />the Government Highline laterals and the Kiefer Extension of the Grand Valley <br /> <br />Canal. The first measurements were made in the last quarter of August and <br /> <br />the second measurements were made in late September through early October. <br /> <br />The measurements were made using standard Water and Power Resources Service <br /> <br />procedures as described in the Water Measurement Manual, Two people, one at <br /> <br />the head and the other at the end of the reach, performed the measurements. <br /> <br />To check accuracy, duplicate measurements were made by different individuals <br /> <br />and instruments. Values of flow obtained in this manner 'were always within 5 <br /> <br />percent and generally within 2 to 3 percent of one another. <br /> <br />10 <br />