WSP01110 - Laserfiche WebLink

Home Browse Search

.- CJl ~... <=> I I i I ! ! ! ,. :, , . , :~ ... '-;., " .< ;~ :"' '.. ".;. \~ ., '.~ " ;:.1 :-';1 .J ., :J James, Marland, Meeker, and Scott Wells. A network of observation wells and seep measurement stations were installed to monitor the effects of the verification program. The bores of the James and Scott Wells were cleaned, tested, and successfully plugged. Major difficulties were encountered with the Marland Well. An adjacent intercept hole was drilled and used to plug it by using pressure cementing from the intercept hole. This was apparently successful in' stopping the last source of seepage from .the dome and eliminating the need for replugging the Meeker Well. . Nonpoint Source Control Management of nonpoint sources to control salt loading from rangelands has been investigated through State and Federal cooperative efforts in Utah and Colorado. The Utah study was completed in 1991; and in Colorado, results of the study were released in 1992. In both States, all watersheds draining into the Colorado River Basin were studied to estimate contributions of salt from nonpoint sources and to determine the potential for treatment. The watersheds with the highest priority for treatment have been identified in each State. Palo Verde lITigation District The Palo Verde Irrigation District (PVID) is a privately developed district located in Riverside and Imperial Counties, California. Water for irrigation is divened from the Colorado River at the Palo Verde Diversion Dam and is conveyed through 253 miles of main canals and laterals to serve approximately 90,000 acres of cultivated land. The irrigation return flows are collected in a 149-mile drainage system and returned to the Colorado River. A record of water and salt for PVID since 195 I shows that for most years, the return flow carried about 10 percent more salt to the river than was diverted from the river. Because the drainage flow is so large (about 500 ft'/s), no alternative beneficial use for the water has been apparent. Consequently, investigations have focused on ways to minimize the increment of salt load that the drainage carries in excess of the salt load diverted with the irrigation water. The most recent land brought into production is in the southern end of Palo Verde Valley, and drains there collect water with the highest salinity concentrations. This land has been under irrigation for only 20 to 30 years, a relatively short time in comparison to the irrigation history of the valley which began about 1880. In 1984, an 18-month study was initiated to determine the salinity mechanism responsible for salt loading at PVID. Analysis of the data collected during the study showed that salt loading is due to flushing of saline water from the southern portion of the district. There was no indication of saline water entering the district from either Palo Verde Mesa to the west or from the underlying Bouse Formation. Neither salt beds nor salt-laden materials were found. Analysis of water samples taken from the outfall drain show a downward trend in salinity concentration since 1966. This indicates that salts are being gradually flushed from the aquifer. This trend and the high cost of measures to control salinity led Reclamation to conclude that salinity 34