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<br />Development of Estimated Daily Flows - Yampa River at Maybell <br /> <br />acre-feet (1965). Division 6 has estimated depletions of over 100,000 acre-feet in recent years, <br />although this estimate includes some agricultural depletions occurring below the Maybell gage. <br /> <br />Maybell Canal Depletions <br /> <br />The Maybell Canal diverts water from the Yampa River approximately four miles <br />upstream of the Mayben gage. Water diverted by the Canal serves lands located several miles <br />downstream. For purposes of this study, it was assumed that diversions by the Maybell Canal <br />were 100 percent consumptive with respect to the gage. With this assumption. the adjustment <br />to gage flows at Mayben was made simply by adding back in the daily diversions observed <br />from 1950 to 1982. No routing correction was applied to these diversions because of the close <br />proximity of the Canal to the Maybell gage. <br /> <br />Daily Basin Export Depletions <br /> <br />Several ditches within the Yampa River Basin divert water for export to another basin. <br />Three of these exports occur upstream of the Maybell Gage. For purposes of this study. it was <br />assumed that these diversions are 100 percent consumptive with respect to the Maybell gage. <br />With this assumption, the adjustment made to reflect these depletions was simply to account for <br />observed historical diversions by these ditches and route this effect based on travel time <br />estimates. Diversion records were cbtained from the Division 6 Office of the State Engineer. <br /> <br />Daily Reservoir Depletions <br /> <br />Three types of reservoir depletions were accounted for in the estimation of virgin flows: <br />(1) depletions from evaporation, (2) depletions from first fill, and (3) depletions from reservoir <br />operations. Calculations explicitly accounted for depletions from five reservoirs: Steamboat <br />Lake, Lake Catamount, Yamcolo Reservoir, Stillwater Reservoir and Elkhead Reservoir. <br />Reservoir depletions from other reservoirs and open water bodies (e.g.. stock ponds) above the <br />Maybell gage were aggregated in each of the three water districts. Depletions were computed <br />on a monthly basis and then disaggregated into daily values using a quadratic spline <br />interpolation scheme that preserved the total depletions in each month. <br /> <br />Evaporation and first fill depletions were calculated for Steamboat Lake. The reservoir <br />was assumed to remain full after it filled for the first time in the spring of 1963. The monthly <br />evaporation depletion was computed as the average surface area from the current and previous <br />months multiplied by the net evaporation rate for the month. Evaporation rates were taken <br />from the Phase 1 study. The first fill depletion was computed as the capacity of the reservoir, <br />and was assumed to take place in April of 1963. The monthly evaporation and first fill <br />depletions were then disaggregated into daily values using a quadratic spline interpolation <br />scheme that preserved the total depletions in each month. <br /> <br />Evaporation and first fin depletions were also calculated for Elkhead Reservoir and Lake <br />Catamount in the same manner as described above for Steamboat Reservoir. However, the <br />first fin for Elkhead Reservoir was assumed to take place in April of 1974. The first fill for <br />Lake Catamount was assumed to take place in April of 1977. <br /> <br />7 <br />