Limestone-Graveyard Creeks Watershed Plan and Environmental Assessment

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45J' Project action will reduce deep percolation which will improve ground water and Arkansas River water quality. This is achieved through reduced loading of heavy metals, pesticides, salts, nutrients and sediment. Water Ouantity The Fort Lyon canal company's estimated amount of water available from diversions, reservoirs and pumping averages approximately 400,000 acre feet for 91,000 irrigated acres served by this canal. This equates to an average of 4.44 acre feet /acre /year for this watershed's 44,500 irrigated acres. However, it varies considerably from year to year. Present irrigation systems in the Limestone - Graveyard Creeks Watershed contribute to poor-irrigation application. The average irrigation requirements for the crop rotation for the project area are about 20 inches per acre per year over and above normal precipitation. Serious crop production reductions occur in the watershed during water short years. This issue was evaluated in light of the Arkansas River Compact. It was considered in the alternative section. Analysis information can be found in Appendix C. The compact states in Article IV -D that, "This compact is not intended to impede or prevent future beneficial development of the Arkansas river basin in Colorado and Kansas by federal or state agencies, by private enterprise, or by combinations thereof, which may involve construction of dams, reservoirs and other works for the purposes of water utilization and control, as well as the improved or prolonged functioning of existing works: Provided, that the waters of the Arkansas river, as defined in article II, shall not be materially depleted in usable quantity or availability for use to the water users in Colorado and Kansas under this compact by such future development or construction ". Irrigation Induced Erosion Excessive irrigation induced furrow erosion is occurring on approximately 15,000 acres. This occurs mainly in the upper portions - (300 feet) of the fields. This erosion averages 42 tons per acre per year. Lower portions of fields are damaged by sediment disposition. An estimated 2 -3 tons of sediment is contributed to the Arkansas each year per acre eroded. This sediment travels to the Arkansas River through drains and creeks, frequently clogging channels and restricting flows. The sediment is contributing to the reduction in flow capacity of the Arkansas River downstream. Some areas of the river are becoming seriously restricted, increasing flooding problems downstream. In addition to sediment, high concentrations of total dissolved solids (TDS), heavy metals, and nutrients are being carried downstream to other users. Yield reductions from the erosion and sedimentation may occur on the fields in the watershed. Rural Water Problems 17 1 i A