WSP03103 - Laserfiche WebLink

Home Browse Search

t... <;'J L'? Q ::-, -..' .... . . from Stage One would be evaluated before deciding to proceed with construction of the rest of the unit. Stage One development would involve the concrete lining and rehabilitation of structures along a 6.8-mile section of the Government Highline Ca- nal between Big Salt Wash and Mack Wash in the western end of Grand Valley. Thirteen laterals that now ~erve the area under the canal section to be lined would be consolidated into 11 and placed in pipe sections. About 6.5 miles of interceptor ditch and four small detention ponds would be constructed above the canal section to prevent runoff from entering the canal. Some existing cross-drainage features would be en- larged. A field station would be constructed as part of the Stage One development for use as a construction headquarters and permanent oper- ating facilities for the entire unit. To com- pensate for wildlife habitat losses, an area of suitable land would be acquired and initially de- veloped, and a watering pond would be construc- ted above the Government Highline Canal. Data will continue to be gathered to determine the nature and extent of the salt loading to the Colorado River. Such data will include the following: (1) flow measurements and samples from all major washes and drains; (2) samples and water levels from existing observation . Grand Valley Unit December 1979 Page 2 of 2 wells in the Reed Wash Study Area; (3) samples and water levels from an extensive network of wells valleywide; and (4) computation of water and salt budgets for the Grand Valley and for the Reed Wash Study iI.rea. An extensive drilling program has been completed to obta!n subsurface geologic data along all of the major canals in the valley. The core samples obtained will yield information on the presence and extent of expansive clays, depths to water, and the type of sedimentary materials all of which will affect the engineering design of the canals and laterals. LOCAL INTEREST Construction costs (January 1979 costs) Canal lining and improvement Lateral improvement Permanent operating facilities Wildlif e plan Investigations prior to authorization Irrigation Management Service&h/ Total Interest during construction (5 years at 5.625 percent) Less costs of investigations prior to authorization Total investment for economic analyses Annual equivalent costs (50 years at 5.625 percent) Construction costs Increased operation, maintenance, and replacement costs Total Cost per mg/L of salinity reduction at Imperial Dam 1/ Represents monies already program will be discontinued after Interest in the Grand Valley Systems Improvement Program by Federal, State, and local concerns is continually growing. In keeping with this interest, the Grand Valley Salinity Coordinating Committee meets regularly and is open to all persons and agencies interested in attending. The purpose of the committee is to ,;oordinate all salinity studies and to disseminate Llformation to the public. The contract between the U.S. and the Grand Valley Water Users Association for the repayment of opera- tion, maintenance, and replacement costs on Stage One is still in negotiation. STATISTICS (TAKEN FROM SPECIAL REPORT FOR STAGE ONE) EFFECTS ON THE COLORADO RIVER (average annual) ",:',';-. Decrease in salt load (tons) . . . Reduction in depletion (acre-feet) Reduction in salt concentration at Imperial Dam from decrease in salt load (mg/L) . . . . . . . . 2.5 24,000 200 ESTIMATED COSTS PROJ~ FEATURES 6.8 Canal to be lined (miles). . . . LatP-rals to be improved (miles) Existing. . . . . . . After construction. . Detention ditch (miles). Detention ponds (number) 34.2 29.0 6.5 4 $8,285,000 8,455,000 420,000 790,000 25,000 25,000 18,000,000 700,000 -25,000 18,675,000 1,123,000 10,200 1,133,200 453,000 expended, though the 1979.