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the carrier (Empire Canal-La Jara and Empire Canal-Alamosa). In these instances, the operating <br />rules used to carry water to transfer ditches on other rivers are set to a priority just junior to the <br />rules associated with the original structure. <br />There are currently 143 rules (Rule Types 11 and 14)in the Rio Grande model to represent these <br />types of practices. Carrier operating rules used in Phase la modeling efforts to represent <br />carrier ditch systems are shown in Table 14 (Attachment 4). <br />Summary of Operating Rules <br />There are currently 346 operating rules defined in the Rio Grande surface water model. <br />Additional rules will be developed as overall model development progresses. For example, <br />operating rules will be implemented to model the Rio Grande Compact as currently administered <br />by Division 3, and additional rules may be required to accurately represent groundwater use in the <br />basin. Table 15 summarizes the operating rules that are currently implemented in the Phase la <br />model. <br />Table 15 <br />Operating Rules Used in Rio Grande SurFace Water Model <br />Rule Description <br />Type <br />Number of <br />Applications <br />2 Reservoir Release to a direct diversion demand or carrier 57 <br />6 Physical Exchange or Paper Exchange (bookover) 20 <br />9 Release for target contents 12 <br />11 Direct flow demand thru intervening structures 197 <br />14 Similar to No. 11 but diversions are constrained by demand at carrier structure 3 <br />16 Reservoir storage using direct flow diversion rights 57 <br />Total 346 <br />Comments and Concerns <br />The current Rio Grande surface water model represents Rio Grande Compact obligations in a <br />simplified manner. In an effort to mimic historical deliveries from the State of Colorado, <br />historical flows at the Colorado-New Mexico state line have been used to define the senior-most <br />priority in the basin. This ensures that model operation will result in flow conditions that were <br />historically observed. This representation of the Compact has been useful in the water balance <br />approach of the initial calibration efforts. <br />Because of the uniqueness of the Rio Grande Compact and its administration, and because of the <br />important implications it has on water availability in Colorado, new operating rules are being <br />developed by the State that allow more accurate representation in StateMod of current Compact <br />administration practices. These rules follow current practices of using flow forecast information <br />at several "index" stream gages to estimate annual delivery obligations, and actual year-to-date <br />Compact deliveries to continuously estimate remaining delivery requirements throughout the <br />year. (Additional information concerning current administration of the Rio Grande Compact can <br />be found in a memorandum documenting discussions with the Division 3 Engineer). These rules <br />will be implemented during the next phase of development of the Rio Grande surface water <br />model. <br />C:Acdss\Task6-l0.doc Prepare Operating Criteria File February 24, 2000 -Page 4 of 5 <br />