WSP00631 - Laserfiche WebLink

Home Browse Search

I :;:.~~?i:0 (.>) ....' o ..r~ Some have postulated power plant cooling ponds as pne source of some underground flow and saline springs as another. It was determined beyond the scope of this study to trace and quantify such sources, and, in any instance, would not be affected by a USDA salinity control program. The contributing watershed for this area of the San Juan is expansive, covering a large area of northwestern New Mexico. , As for the increased salinity in the Colorado River caused by irrigation agriculture, Table 5 displays the reductions in salt pick up that could reasonably be expected by implementing a program to improve onfarm irrigation efficiencies by an average of about 20 percent and reduce about two-thirds of the off-farm seepage from canals and laterals by the use of pipe and concrete lining. Onfarm, deep percolation has been estimated to account for nearly one-half of the total return flow. Deep percolation, in percentage of water applied, ranged from about 11 percent to about 95 percent on the farms evaluated. Excessive {:':~~ Q~~ irrigation set times on fields with relative short lengths of run are considered a major factor in the production of both tailwater and deeply percolated water. On some of the farms, irrigation water management could be implemented at once to reduce excessive set times which would immediately reduce some of the deep percolation and tailwater. Other farms will need improvement in onfarm irrigation systems before irrigators will be able to manage the water effectively. lS An onfarm program to improve about 80 percent of the furrow irrigation systems would involve such land treatment and management. practices as ditch lining, gated pipe and surge valves, water control structures, land leveling, and irrigation water management. The onfarm program would reduce salt loading by about 26,000 tons per year. Program costs for the onfarm improvements at $600 per acre on 6,700 acres would be about $4 million. Average annual cost for onfarm salt load reduction would be about $13 per ton. ~ ~ _' -~ - 600{! 700.; ::: 'f,ozG,OO:> - ~ L{ Plq D"~. -/-t,~ ~.