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,. o ~ ~'., to Location Description Authorization Land certification Definite plan report Benefit C08t niIIo8 .. of October 1, 1993 Completion data 0Qn~1 lL '-,.;.- ~ '-'~,,' _' , c, Colorado River Basin Salinity Control Project Grand Valley Unit Colorado This unit Is located In Mesa County in western Colorado at the conflli.nc::e of the Gunnison and Colorado Rivers near Grand Junction. ;; Irrigation In the entire valley area encompasses 70,500 acres, with 2QO mll._ of canals and approximately 500 miles of laterals, most of which are ea;th lined. Much of the land has been Irrigated for more than 50 years, and It Is '.timated thaff the Grand Valley contributes about 580,000 tons of salt annually to the Colorado ' River. Investigations indicated that lining canals, lining or piping latetals, rehabilitating or replacing canal and lateral structures, and constructi/'lg adequate measurement control devices could reduce the salt contribution 161,400 tons per year while the Irrigation Management Scheduling and on-farm improvements should result in an additional reduction of 130,000 tons per year. Stage 1 consisted of concrete lining 6.8 miles of main canal and placing 30 miles of laterals in pipe on the Govemment Highline Canal. Stage 2 proposel!to membrane line the remainder of the Govemment Highline Canal and ,place pipe in 110 miles of Federal laterals and 214 miles of laterals In private irrigation systems. Public Law 93-320, June 24, 1974; and Public Law 98-569, October 30, 1984. None required. Stage 1 approved March 25, 1980; Slage 2 approved July 11, 1986. All addendum was completed December 20, 1990, for the Price and Stubb Ditches. Previous agreements with the Mexican Govemment concerning salinity control In the Colorado River and Public Law 93-320 are based upon .social andpo/Itlcal justifications. Public Law 98.569 required construction preference be given to those projects that reduced salinity at the least cost. The cost effectiveness of this unit is measured in terms of annual cost for each milligram per liter (mg/I.) of salinity reduction in the Colorado River at Imperial Dam. The annual COst of the unit is $17,764,000 which includes the total investment annual equivalent.costof $17,430,000 at 5.625 percent for 50 years, plus the annual OM&R of $334,000. The decrease in the OM&R is due to a change in the way indexing Is calcuJ~ted.Thls figure represents actual costs rather than projected cost indexing. The annual removal of 161,400 tons of salt from the Colorado River at Grand Valley ,esults In a salinity reduction at Imperial Dam of 14.7 mg/L. The annual cost per ton is $110. The unit will be completed in 2003. As of September 30, 1992, the unit is 36 . percent complete. 1l'l1 '.""