WSP01604 - Laserfiche WebLink

Home Browse Search

ALTERNATIVE PlANS Study Methods and Assumptions A sampling procedure was devised for planning farm irrigation systems on the lands v.hich will be converted to irrigated cropland. The sample was based uJXln the rumber of farm delivery JXlints or separate fields in the area. It was agreed that a target of ccrnplete plans on 25 fields or systans would adEljuately represent the project area. A Dry Cropland Analysis, including net returns/acre, was mt inserted in the report since the farmers have already or will be signing an agreement with the Dolores Water Conservancy District to accept the water. Resource Conservation plans were ccrnpleted for ten landowners. These plans covered 27 separate fields or systems. They represent over 10 percent of the project area. Alternative irrigation system designs were developed for each system. The designs included system layouts, pipeline size and length, sprinkler design, estimated installation cost, estimated anrrual cost, using three different payment methods, and estimate<;! crop returns. Landowners were interviewed before alternative plans were developed. Their anticipated cropping pattern was used in the planning process. These patterns were either 5 years alfalfa, 1 year small grains and 1 year of dry beans or 5 years alfalfa and 2 years small grains. Using this information, the irrigation system plans were based upon a full water supply to alfalfa. Three general field irrigation system types were used in the development of alternative plans. These were (1) a surface system using corrugations or furrows, (2) a sideroll sprinkler system and (3) a center pivot sprinkler system. It was assumed that tmderground pipeline would be used to transfer water fran the farm turnout to v.here it was needed on the field. Maps obtained fran the Bureau of Reclamation showed the topography, lands designated by the Bureau as irrigable, and the locations of farm turnouts. Other basic data available were soil maps, aerial photos, irrigation guides and technical guides. The next step in the planning process was an on site inspection of the field. Indications of archaeological sites, gullies, seep areas and other physical barriers were identified and located on aerial photos. Soil conditioning indices were developed in the conservation plans for all cropping systems anticipated by the farmers. Conservation practices such as conservation tillage, crop residue, and irrigation water management, are being encouraged in all rotations. All rotations, thus far, have been within acceptable tolerance levels of erosion men under sprinkler systems. In the future, conservation planning will continue to encourage management and/or structural practices to maintain acceptable erosion rates. If alfalfa is not part of the rotation then such practices as terraces, conservation tillage, dammer/diker implements, grassed water \,ays, and contour farming may be needed. Costs and benefits on a case by case basis will be considered at that time. -9-