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<br />ANNUAL OPERATING PLAN FOR WATER YEAR 2003 <br /> <br />~ <br />..-' <br />:) <br />l'.j <br /> <br />Three operation studies were developed for the C-BT to establish an AOP for Water Year 2003. <br />Each of the studies conformed to the established operating criteria but used differing inflow <br />conditions and water demands. <br /> <br />QO <br /> <br />The possibilities of all three inflow conditions were determined from a probability analysis of <br />historic monthly inflows, and were labeled reasonable minimum, reasonable maximum. and most- <br />probable. Reservoir inflow during Water Year 2003 has a one-in-twenty chance of being less than <br />the reasonable minimum and a one-in-twenty chance of being greater than the reasonable maximum. <br />Statistically, inflows in 2003 will have a nine-in-ten chance of falling between the two extremes. <br />The most probable inflow is based on long-term averages and approximates a 50 % chance of <br />occurrence. The three studies for Water Year 2003 are summarized numerically in tables 5A. 5B. <br />and 5C and displayed graphically in exhibits 4 through 9. The annual operating plans for Green <br />Mountain Reservoir are also summarized in table 6. . <br /> <br />The AOP, as developed and reflected in the three studies, provides the flexibility to adjust operations <br />as conditions change during the Water Year. Forecasts of the April-July reservoir inflow will be <br />made at the beginning of each month from February through June. The majority of snowmelt runoff <br />occurs in the April-July period. Projected operating schedules will be adjusted, as required <br />throughout the Water Year, as changes occur to the forecasted inflows. irrigation demands, <br />maintenance schedules. and power loads. <br /> <br />OCTOBER-JANUARY PERIOD <br /> <br />The three studies for the October-January period of Water Year 2003 are similar because winter <br />inflows are nearly the same under the three conditions of inflow. The most probable inflow <br />condition is utilized for the 2003 October-January C-BT operations and is summarized in the <br />following paragraphs. Operations for this period reflect scheduled maintenance on several <br />powerplants and restricted elevations on Horsetooth Reservoir. <br /> <br />Green Mountain Reservoir <br /> <br />Green Mountain Reservoir began the Water Year with 48,545 acre-feet in storage, almost 75,000 <br />acre-feet below the 30-year average. Releases for bypass of inflow and CBT replacement continued <br />from Water Year 2002 into October. Depletion by Colorado Springs and Denver occurred during <br />this period. Releases from Green Mountain Reservoir for replacement, bypass of inflow, power, and <br />river and reservoir operations totaled 33.396 acre-feet during the November-January period. These <br />releases decreased the storage to approximately 39.789 acre-feet by January 31. <br /> <br />Turbine releases for replacement. bypass of inflow. power. and reservoir regulation were varied <br />during the first 4 month of the Water Year, ranging from 60 fi'/s in early October to 300 ft3/s in early <br />November. The average flow out of Green Mountain Reservoir for the period October-January was <br /> <br />15 <br />