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<br />. <br /> <br />Draft <br />San Juan Operating Model <br />Consideration for Operating Rules <br />February 24, 1998 <br /> <br />H17<<cn/n en;- L <br /> <br />Note: Considerations here are considered preliminary. Conditions finally recommended are <br />subject to the results of the Biology Committee integration process to determine the biological <br />and geomorphic requirements for the fish and their habitat. These values and rules have been <br />used in model runs presently being analyzed and are being studied for adequacy and <br />appropriateness. <br /> <br />· Minimum peak release consists of 1 week ramp to 5,000 cfs, 1 week at 5,000 and one <br />week ramp down. Volume is 140,000 af <br /> <br />· Primary peak release hydro graph consists of 4 week ramp to 5,000 cfs, 2 weeks at 5,000 <br />cfs and 4 week ramp down. Volume is 420,000 af. <br /> <br />· Median Peak on Animas is May 30. No correlation between volume or magnitude of <br />runoff and date of peak exists. Fix center of 5,000 cfs release at May 30 every year. <br /> <br />. <br /> <br />Use attache'd decision tree to determine magnitude of release. Available water on the <br />chart is defined as: predicted inflow less base release plus available storage, where <br />available storage is reduced from full storage by the amount of carry over storage <br />necessary to prevent shortages in future years. "Release last 3 years> 420,000 at." <br />means that a release of at least 420,000 af occurred during at least one year out of the last <br />3. Iterations of model runs will be required to set minimum allowable storage. <br /> <br />. <br /> <br />· In years when spill is predicted to be greater than 420,000 af, adjust the hydro graph by <br />first adding a nose of 2,000 cfs and extending to as early as March I. Increase nose by <br />500 cfs and increment calculation of duration until time extension is March 1 if <br />necessary. Ramp up on beginning of nose from base flow cannot exceed 1,000 cfs per <br />day. <br /> <br />· In years when the release will be greater than 140,000, but less that 420,000 af, use the <br />following adjustment rules in this order of preference: <br />1. Decrease time of decending limb by as much as 3 weeks to achieve necessary <br />reduction (105,000 afreduction possible - 315,000 af release) <br />2. Decrease time of ascending limb by as much as 3 weeks to achieve necessary <br />reduction(105,000 afreduction possible - 210,000 afrelease) <br />3. Reduce duration of peak by as much as I week (70,000 afreduction possible- <br />140,000 af release) <br /> <br />· Minimum base flow following spring peak is 500 cfs at Farmington, Shiprock, Four <br />Corners and Bluff gages (average of any two gages). Minimum release - 250 cfs. <br /> <br />. <br /> <br />Flood control releases to be handled as a spike flow (high magnitude, short duration), <br />released when flood control rules require, except that the release shall not occur earlier <br />than September I. If an earlier release is required, extend descending limb of <br />hydro graph. <br /> <br />. <br />