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<br />released from Heron Reservoir, which was also simulated in the San Juan RiverWare model. The <br />release pattern from Heron Reservoir followed the mean call paltem of the current San Juan- <br />Chama contracts. <br /> <br />The ALP Project impacts were simulated in RiverWare by explicitly entering the various project <br />features and defining their operation in the system. To meet daily minimum flow requirements in <br />the Animas River, a daily operation loop was employed to determine allowable pumping to <br />Ridges Basin reservoir. All other computations were completed on a monthly time step. <br /> <br />Before using the San Juan RiverWare model for project analysis, it had to be validated, verified, <br />and calibrated like any model. The configuration of the model was validated by having the <br />model simulate gaged flows from the natural flows and the historical depletions, reservoir <br />releases, and flow routing used to compute the natural flows. This was essentially a back- <br />calculation of the gaged flows from the natural flows. The model configuration was determined . <br />to be valid once the simulated flows at all gage points matched the gaged flows. <br /> <br />Once the model configuration was validated, reservoir operation rules were substituted for the <br />historic releases, and the model was rerun. The reservoir operating rules were calibrated so that <br />the end of month reservoir contents closely matched the historical observed contents. Once this <br />match was obtained, rules designed to simulate the Type I shortage were implemented and the <br />full irrigation demands substituted for the historical shorted demands. Again the rules were <br />adjusted until the simulated flows at all gauging stations closely matched the observed gaged <br />flows. Once this was achieved the model was assumed calibrated and verified. <br /> <br />Simulation of reservoir operations, particularly operation to "mimic" natural flows, requires <br />forecasts of reservoir inflows. For forecasting inflows to Vallecito and Lemon reservoirs, the <br />fraction of the deviation of the actual inflow from the mean inflow is added to the mean inflow. <br />The deviation fraction starts small early in the year and approaches 100% when close to the peak <br />runoff month. For the Navajo Reservoir operation simulation, a forecast error approach is used, . <br />whereby the mean historical forecast error for each month is predetermined and applied. <br />Operation of Navajo Dam to maximize peak flows also requires forecasting the time of peak <br />runoff for the Animas River, allowing releases from Navajo Dam to match the Animas peak. At <br />this time, a constant peak release date has been uti Iized, since no significant relationship could <br />be developed for predicting timing of the Animas peak. The required timing of the peak release <br />from Navajo Dam was adjusted to optimize the hydrograph statistics to mimic the 1929 to 1993 <br />period of analysis. <br /> <br />The model in its present configuration represents the best science available to assess the impacts <br />of water development on the ability to meet flow recommendations for endangered fish and to <br />test operating rules designed for that purpose. The presently defined operating rules and model <br />configuration do not indicate availability for substantial additional depletions in the basin with <br />the present flow recommendations. Further modification of the operating rules and/or <br />improvement in the simulation of system operation in the San Juan River would be required to <br />demonstrate the possibility of further development within the limits of the present flow <br />recommendations. <br /> <br />Configuration for No Action Alternative <br /> <br />"',," . <br /> <br />A-6 <br />