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<br />001996 <br /> <br />The lag correction, which is used in all model runs, is a series of positive and negative numbers and <br />looks like another gain/loss file. However, the annual sum of the correction is zero. The net effect <br />of these gain/loss files will be to reduce summer and increase winter return flows at each node. <br />These corrections are added as new objects to the San Juan Model. The following objects contain the <br />lagged return flow correction in the local inflow slot within the San Juan Model: <br /> <br />LaggedRF _Fix _ AnimasAbvFarm <br />LaggedRF _Fix_SJAbvFarm <br />LaggedRF ]ix _ SJAbvShip <br /> <br />Corrections Due to Missed Colorado Depletions in Natural Flow <br />Calculations <br /> <br />The state of Colorado believes that there was a mistake made in the development of the natural flow <br />estimates. The natural flow calculations apparently missed some Pine River depletions and other <br />depletions attributable to high mountain pastures in Colorado. The Model would therefore double <br />count some of ColoradoOs depletions. To mitigate this problem, a correction was implemented which <br />amounts to additional inflows on most of the major tributaries. This correction was incorporated for <br />the Animas, Florida, La Plata, Navajo-Blanco, Piedra, Pine and Upper San Juan basins. It was <br />calculated by taking the 65 year average depletion from a current condition model run, subtracting the <br />1996 Opinion Baseline depletion for the same area and dividing the result by the current condition <br />depletion. This single ratio was multiplied by each monthly depletion from the current condition run <br />producing a new set of monthly values that are included in the Model as a local inflow. <br /> <br />The correction was added as a monthly time series to the following objects/elements in the San Juan <br />Model. The values in square brackets [3,362] show the average correction in ac-ft applied to each <br />basin. <br /> <br />AnimasCO_NF_Fix (added as a new element to AnimasToDurango) [3,362] <br />F1oridaCO _ NF _Fix (added as a new element to F1oridaBelowLemon) [9,104] <br />LaPlataCO_NF_Fix (added as a new element to LaPlataToHesperus) [241] <br />NavBlancoCO NF Fix (added as new object) [469] <br />PiedraCO NF Fix (added as a new element to PiedraAbvArboles) [381] <br />PineCO)fF_Fix (added as new object) [7,832] <br />UpSanJuanCO_NF_Fix (added as a new element to SJAbvPagosaSprings) [1,467] <br /> <br />The sum of these files is 22,858 ac-ft. These calculations were completed in a spreadsheet named: <br />depletions CurCondx CO NF Fix.wb3. <br />- - - - <br /> <br />It should be noted that the current condition run was configured by the USBR and represent the 1993 <br />depletion levels propagated throughout the Model. All Municipal and Industrial demands are set at <br />1993 levels. The Agricultural demands are at 1993 acreage levels, but the depletions fluctuate from <br />month to month and year to year based on climatic conditions. <br /> <br />DRAFT - SJRIP Hydrology Model Documentation <br />June 18, 1999 <br /> <br />57 <br />