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Irrigation Techniques in the District <br />District 20 has experienced a very significant movement toward use of sprinkler application <br />systems. This movement began in earnest some 30 years ago and continues today. <br />Approximately 80 percent of the water used for irrigation in District 20 is applied through <br />sprinkler systems, although some of this water is supplied from the intentional recharge efforts <br />using surface diversions. Water supply for these systems comes from both groundwater wells <br />and from surface diversions (storage regulation and pumping). The majority of wells within the <br />District were constructed between 1952 and 1981. <br />Most smaller ditches, with rights between 1 and 10 cfs, utilize flood irrigation techniques. For <br />example, there are only six sprinkler systems, four of which use direct flow river diversions to <br />operate as opposed to wells, located in areas to the west of Del Norte. To the west of Del Norte, <br />ditches tend to be much smaller as compared to those between Del Norte and Monte Vista. <br />Cropping in the District <br />Cropping in District 20 consists of a mix of field crops including alfalfa, barley, wheat, carrots, <br />potatoes, and pasture. Irrigated acreage information is provided by water users in the District on <br />an annual basis and this information is recorded in the State's database. <br />Return Flows <br />Return flows within District are utilized by the Commissioners to help them administer water <br />supply. The amounts of returns are monitored such that native water can most efficiently be <br />provided to water users. There are portions of the River where ditch owners essentially "live off <br />of the returns from upstream irrigators. This situation is most pronounced in the area to the <br />south and east of Monte Vista. Upstream of this point the Commissioners may allow what would <br />initially appear to be out-of-priority diversions, while in fact relying on return flows to meet <br />downstream senior rights. This system of administration has developed through years of <br />administrative experience, and requires close attention to changing River stages. <br />Much of the losses experienced by canals and ditches serving lands to the north of the Rio Grande <br />serve to recharge both the confined and unconfined aquifers within the Closed Basin. Little, if <br />any of these losses return to the Rio Grande because of a natural hydrologic divide separating the <br />Closed Basin from the River. <br />Additional return flows are picked up by the numerous drain systems that have been constructed <br />As described, these drains, while originally constructed to eliminate unwanted excess water, are <br />now commonly used as a supplemental supply and have been decreed as such. <br />River Gains and Losses <br />In recent years District Commissioners and the Division 3 office have, on occasion, conducted <br />gain/loss studies on the Rio Grande and its tributaries. These "seepage runs" are conducted by <br />measuring all inflows and outflows within a defined river reach. Amass balance for the reach <br />then establishes natural gains or losses to and from the river. Several seepage runs have been <br />conducted for different parts of the Rio Grande mainstem and at various times of the year. <br />Seepage studies have also been conducted on several of the major canal systems in the District. <br />The results of seepage studies are on file in the Division 3 office. <br />C:Acdss\D20_Mem.doc District 20 Interview July 2, 1999 -Page 8 of 9 <br />