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Direct flow storage operating rules are activated in the model by setting variable ioprsw(k) to the <br />year in which direct flow storage was decreed. <br />Concerns <br />None <br />Rio Grande Compact <br />Overview <br />The obligation of Rio Grande deliveries from Colorado to New Mexico is defined by the Rio <br />Grande Compact and is one of the most critical components of water management in the Rio <br />Grande basin. It is, therefore, an important component of any model attempting to simulate water <br />rights administration and water management on the Rio Grande. Modeled Compact <br />administration must 1) estimate Compact delivery obligation based on forecasted inflows and <br />observed flows to-date, and 2) curtail other water rights in the basin to ensure that the delivery <br />obligation is met. <br />Objective <br />Test StateMod's Rio Grande Compact operating rules that allow representation of the Rio Grande <br />Compact as it is currently administered by the State of Colorado. Under current practices, <br />administration of the Rio Grande Compact involves a complex series of calculations that occur <br />regularly throughout the year that considers forecasted inflows at several locations, flow to-date, <br />and delivery obligations as defined by Article 3 of the Compact. <br />Test Application <br />This enhancement to StateMod involved the creation of two new operating rules (Type 17 and <br />Type 18) for implementation in the operating criteria file (rg. opr). Two rules are required <br />because of differences in the Compact calculations between the Conejos River and Rio Grande. <br />A test application for this enhancement was provided by the State, Example No. 39, and may be <br />reviewed as found in the StateMod documentation. Hydrosphere ran StateMod with the Example <br />No. 39 input data and reviewed the output. Following several adjustments by the State to the <br />internal Compact calculations, the output indicated that the StateMod enhancement was generally <br />operating as intended. <br />Rio Grande Compact operating rules were then added to the operations file for the Rio Grande <br />Model. The model network was also modified to include two additional instream flow nodes that <br />are required to represent delivery obligation points for both the Conejos River and Rio Grande. <br />The results indicated that StateMod could successfully curtail water rights in the basin to attempt <br />to deliver the calculated flow obligation at the State line. However, when comparing the <br />simulated delivery to actual historical delivery there were significant differences that needed to be <br />addressed. Further discussions with the Division 3 Engineer led to additional refinement of the <br />Compact administration code in StateMod. Subsequent model runs and review of output showed <br />more favorable comparisons and the Compact rules were judged to be operating as desired. <br />The StateMod rules provide the user flexibility in allowing a maximum annual debit or credit <br />(under or over delivery) (variables gdebt and gdebtx) and estimated flows from the Closed Basin <br />Project (iopsou(8,1)) and the Norton Drain (iopsou(10,1)). <br />C:Acdss\TaskS-5.doc StateMod Enhancements August 15, 2000 -Page 3 of 8 <br />