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LOWER GUNNISON SALINITY CONTROL PROJECT UNIT 1 Introduction: Water is vital to Delta County. The lrrlgation system developed through the past 100 years has firmly established the agricultural industry. However. over irrigation on the farms. seepage and deep percolation from unllned ditches and laterals have created a serious problem for water users in the downstream - both locally and in faraway areas, LEGEND ~.r) ,1. :, rJ, /- I - ~ i ----/~-" -'v' 'I ~ ~./ " i ^ .., 5/ 'I. ,..V.!' / ", ~f' ,.I.:;~:;;... r--::J _ASWIlEREMANCOSSH~LE"'OYOUNGe:RAWNfALClEPQSITS L.:...:.:..J1oI4YOONTIlIIlUTElQrHESALTLOlOFROMSURFACERlINOfF al_lG4TIONRETlIlItFI"OW. [JJ OLIlEIIAlwvIALOEPOSITS . [E2i lAHtlSUOE OEPOSrrs, s:T. ~ ~:~~~T=:AM> REFIlWI;ESOILCXlNSEIl'I"'T1QllS_ICE1~ Soarceof~ Mancos shale underlies most of the Lower Gunnison Basin surrounded by older Dakota sandstone and younger volcanic rocks. In the long past, the Mancos shale formation was developed as marine deposit. The shale consists of grey silty clay and is high in salt content. Lenses of crystalline salts often are exposed during excavation into shale. Excess irrigation water and seepage from ditches percolate down into the shale furmation. The salts dissolve readily and are carried aloug with the water as subsurface retum flow to the river. &g under Unit J1 The SalinIty Control Project at Lower Gunnison Basin is divided into three units. The first unit is bounded by the Gunnison River on the south: Big Gulch, Stingley Gulch and the nort;h reach of Leroux Creek on the east; the forest boundary on the north: and the county line on the west. Colorado River Salinity Control Program Lower Gunnison Project Units Obiectl..... . Reduce deep percolation from irrigated fields by 9,000 acre-ft.. seepage from ou-farm earthen ditches by 8,000 acre ft.. and seepage from off-farm eartheu laterals by 6.000 acre-It. annually. . Reduce salt loading to the river by 82,000 tons annually by the end of the projected 20 year application of the program. . Restore wildlife values by compensating for wildlife habitat loss caused by the implementation of the project. Current Status: (g !!!l Dee.. 19B81 A sign-up of interested water users was conducted over the summer of 1988. during wh1ch 20 ditch groups and 89 indMdual water users indicated interest. Out of these 109 appltcants one group and two indtviduals have been contracted for p"!lects totaltng nearly $150,000. An additional 10 plans are ready fur contracting. A new stgn- up period for more participants wU1 be announced in JanuaIy 1989_ Bow does the cost share work: The construction funding for the Improvement of the irrigatiou system ts based on cost sharing with the federal government paying 70 percent and the water users paying only 30 percent, The eligible practices for cost share are: . On-farm salt load reduction by Improving inigatton water management system. This may be achieved by land grading, levelling. 'improved irrigation system (drip, sprinkler, gated pipe, swge valve) adoption. canalltniug. high or low pressure pipe lines, pump plant for water control etc. . Off-farm salt load reduction by reducing seepage and deep percolation from the irrigation ditches and laterals, The works may include glade stabilization structures, concrete lining of the conveyance ditches. high or low pressure pipelines, water measuiing devices, corrugated metal pipeline, etc. . Permaneut wildlife habitat and sballow water areas for wildllfe wh1ch may include critical area. planting,