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Irrigation Techniques <br />Sprinkler systems, primarily center-pivots, are the principal method of irrigation within the <br />District. Sprinklers account for approximately 95 percent of irrigation in the District's service <br />area. There is also a small percentage of lands that are flood irrigated, although most flooding <br />occurs at the corners of center pivots. There still remain a few flood irrigators on the east side of <br />the District's system. <br />Sprinkler systems in the service area can be supplied with water in several ways. The most <br />common supply is from groundwater pumping from the unconfined aquifer, accounting for <br />roughly 85 to 90 percent of the irrigation supply (most surface water from Farmers Union Canal <br />is used for recharge purposes). Sprinklers can also be supplied from surface diversions, where <br />the water is typically run into small ponds, then pumped to the sprinkler. Many of the center <br />pivots in the service area can be interchangeably operated using both groundwater and surface <br />water. <br />System Gains and Losses <br />A primary emphasis for operations of the Farmers Union Canal is unconfined aquifer recharge. <br />That is, a maj ority of the water diverted is used intentionally to recharge the unconfined aquifer. <br />This water is then recaptured using groundwater wells. As such, Canal and other losses in the <br />conveyance system are viewed as beneficial. The District periodically estimates actual losses <br />from individual canals and for each ditch. <br />With respect to losses from the Farmers Union Canal, losses can be as high as 40 to 80 percent <br />when water is first diverted in the spring. The District can usually meet demand from members <br />when diverting at approximately 500 cfs. <br />Soils within the service area are heterogeneous and tend to be a mix of sand and gravel, which <br />facilitates the recharge efforts. Soils are tight and sandy in the southern portion of the service <br />area and contain more adobe to the north. Gravel and sand are prevalent to the north west. <br />Return Flows <br />The service area of the District is entirely within the Closed Basin. As such, return flows from <br />water delivered by the Farmers Union Canal do not accrue to the Rio Grande and instead enter <br />the Closed Basin aquifers. <br />Interaction with District 20 Commissioners <br />The District communicates with District 20 Water Commissioners on a daily basis. Phone calls <br />are made to the District 20 early each morning to learn about River flow conditions, availability <br />and the last priorities served. The District then calls their ditch riders who adjust the river <br />diversion headgate to the appropriate level. <br />Interaction with District Members <br />Ditch riders for the District are responsible for communicating with District members. The Ditch <br />Riders are kept informed of water requests, and work together to determine the amount of water <br />to deliver to each of the major laterals. The Ditch Riders are also responsible for adjusting <br />individual turnouts to farmers along the conveyance system. <br />C:Acdss\SLVDist.doc San Luis Valley Irrigation District Interview June 22, 1999 -Page 6 of 7 <br />