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<br />00 <br />.,.--l <br /> <br />.....J <br /> <br />~ <br /> <br />, , <br />-.0-' <br /> <br />OIi.;Fann Il'ri gationSystr.ms <br /> <br />(:.' <br /> <br />Water delivered to the farms has been found to cant"in 300 to 500 parts per <br />million of total dissolved solids. Farm ditches histor-ically have been <br />earthen, but in recent years there has been a trend toward concrEte lining <br />or installation of pipelines. The method of irrigation most widely practiced <br />is corrugations or furrows. Very few bOl'der systems and hardly any sprinkler <br />irrigation systems are used. On-farm irrigation efficienc'ies range from 25 <br />to 50 percent dependinq on the management of the individual farmer. Some <br />farms in the area change their water on multiples of a 12-hour period even <br />though soil moisture may be replenished in a shorter time period. This is <br />a conveni ence arrangement that all ows days and ni ghts free for other acti vi- <br />ties. It also fits well with the schedules of the many part-time farmers in <br />the valley. <br /> <br />. The Soil Conservation Service has had a long history of involvement in the <br />problems of salinity in the Grand Valley irrigated area. In 1945 a study <br />was initiated jointly with the local soil conservation district of the pl~b- <br />lems of drainage and salinity control of the irrigated lands. Field trials <br />were aimed primarily at drainage, reclamation of salted areas and restoration <br />of productivity. The pump drainage procedure developed in the study is now <br />being used in the city of Grand Junction to control the level of the water <br />table in an area of new development. <br /> <br />The conservation program in the valley typifies the present status of irri- <br />gation water management in many areas of the Western United States where <br />supplies ..are plentiful and water costs are relativply low. <br /> <br />Return fl OI'IS from i rri gati on, both surface and subsurface, are returned to <br />the Colorado River and not reused on the project lands. Therefore, the <br />quality of the return flows has not been of primary concern to the irriga- <br />tion companies or ~he individual farmers. The salinity of the diverted <br />water and the salinity of the soils irrigated have been of greater concern <br />as these affect land productivity. <br /> <br />Early soil and water conservation emphasis was placed on maintaining a sal t <br />balance in the soil through leaching and installation of interception type <br />subsurface drains. More recently, greater emphasis has been on agronomic <br />and system changes needed to maintain high crop production. SCS records <br />indicate about one-fourth of the irrigated area has been leveled or smoothed <br />to improve the application of irrigation water; 19,000 acres have improved <br />drainage systems; and operators of about 10,000 acres practice a high level <br />of irrigation water management. Field ditch construction and/or lining and <br />w;;,!:er control structures havf> bs::'1 popular practi:::es with the farmers in <br />recent years. Fifty-four miles of lining or piping have been installed. <br /> <br />Technical and cost-sharing assistance has been available in the valley for <br />many years even though emphasis of the various programs has changed from <br />time to time. To date, primary emphasis has not been given to water qJality <br /> <br />.; 8 - <br />