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<br />.}~0 <br /> <br />INTRODUCTION <br /> <br />~o Problem Statement <br /> <br />o <br /> <br />W <br /> <br />~ USGS records on the San Juan River identify the annual delivery of about one <br /> <br /> <br />million tons of salt in two million acre-feet of water to the Colorado River. <br /> <br />The estimates of annual salt loading from Reach 4 in the verification-study area <br /> <br /> <br />is 41,000 tons of salt from the combined reservation and nonreservation lands and <br /> <br /> <br />116,000 tons from the Reach 5 area. <br /> <br />Objectives and Scoue <br /> <br />USDA's objectives in this phase were to: 1) determine whether significant salt <br /> <br /> <br />loading from irrigated land on the Navajo Nation is or may be taking place, and <br /> <br />2) evaluate the potential for onfarm system and irrigation efficiency improvement <br /> <br /> <br />to lower seepage and deep percolation enough to reduce salt loading. <br /> <br />The goal of this investigation was to determine whether an implementation plan 1:;, i.'., <br />c..{".-" <br />.~ ," -.' <br />reduce irrigation-induced salt loading to the San Juan River is warranted, and iY. <br /> <br /> <br />so, to recommend action that would result in an implementation plan to accomplish <br /> <br />the objectives of the salinity control program. <br /> <br />The scope of the study was to obtain sufficient water and salinity data from <br /> <br /> <br />irrigated reservation farmland in Reaches 4 and 5 to make a reasonable estimate <br /> <br /> <br />of the amount of irrigation-induced salt loading taking place in this portion of <br /> <br /> <br />the Navajo Nation Unit. Data were obtained through sampling drain water for <br /> <br /> <br />salinity and evaluating irrigation systems and water management on individual <br /> <br />operating units. <br /> <br />4 <br />