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<br /> <br />. <br /> <br />HISTORY OF WATER RESOURCE DEVELOPMENT <br /> <br />discharges, and studies of future possible <br />salinity control programs. <br /> <br />.~ <br />IV <br />IV <br /> <br />The report recognizes that many natural and <br />man-made factors affect the river's salinity. <br />Consequently, the actual salinity will vary <br />above and below the recommended numeric <br />criteria. However. under the assumptions <br />of streamflow equivalent to the long-term <br />average, a "moderate" rate of increase in <br />water depletions and full implementation of <br />needed salinity control measures, the average <br />salinity can be maintained at or below 1972 <br />levels during the study period of the next <br />15 years. <br /> <br />, <br />k'. <br /> <br />. <br /> <br />The Federal regulations provide for temporary <br />increases above the 1972 levels if control <br />measures are included in the plan. Should <br />vater development projects be completed <br />before control measures are identified or <br />brought on line. temporary increases above <br />the criteria could result and these increases <br />~ill be in conformance with the regulations. <br />With completion of control projects, those <br />now in the plan or those to be added subsequently. <br />salinity would return to or below the criterial <br />level. <br /> <br />Periodic increases above the criteria as a result <br />of reservoir conditions or periods of belo~ long- <br />time average annual river flow also will be in <br />conformance with the regulation. With satisfactory <br />reservoir conditions and ~hen river flows return <br />to the long-time average annual flow or above, con- <br />centrations are expected to be at or below the <br />criteria level. <br /> <br />3. Relations With Mexico <br /> <br />. <br /> <br />The average annual salinity of the water delivered to Mexico at <br />the Northerly International Boundary increased in 1961 from about 800 <br />mg!l to nearly 1400 mg!l and to over 1500 mg!l in 1962. The completion <br />of the drainage ~ells and subsequent pumping of 151,500 acre-feet of <br />drainage water in 1961 from the Well ton-Mohawk District added over 1 <br />million tons of salt to the Colorado River. The district further in- <br />creased their pumping to 213.000 acre-feet in 1962 and added over 1.7 <br />o1111on tons of salt. If the flo~ in 1961 leaving Imperial Dam and <br />arriving at the Northerly International Boundary (NIB) had remained at <br /> <br />21 <br />