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<br />January. This operation was planned to meet power loads, supply
<br />irrigation water, and provide the storage needed to accommodate the
<br />1977 snowmelt runoff. Below normal winter precipitation, inflows,
<br />and heavy Adams Tunnel requirements combined to put Lake Granby
<br />storage 'about 15,000 acre-feet below plan by April I, During Water
<br />Year 1977, Lake Granby reached a minimum storage content of about
<br />222,650 acre-feet on April 27.
<br />
<br />The February 1 forecast of the April-July snowmelt runoff into Lake
<br />Granby was estimated as 59 percent of the recent 17-year average.
<br />The April 1 forecast was 54 percent. The 1977 Water Year was the
<br />third lowest runoff year of record, and the early forecasts proved
<br />to be excellent. The actual April-July runoff into Lake Granby was
<br />105,700 acre-feet and 54 percent of normal. Prior to 1977, the record
<br />low runoff was 88,200 acre-feet which occurred in 1934. In Water Year
<br />1977, a maximum storage content of about 274,700 acre-feet was achieved
<br />on June 19. Thereafter, with continued drawdown for East Slope irri-
<br />gation needs, Lake Granby's yearend storage was about 226,200 acre-
<br />feet which was below a 17-year average of 420,000 acre-feet.
<br />
<br />Below-normal winter precipitation and inflows to Willow Creek Reservoir
<br />gave an early indication of the drought and reduced the amount of
<br />water available for pumping to Lake Granby. The early season forecast
<br />of April-July inflows to Willow Creek Reservoir indicated 42 percent,
<br />38 percent, and 42 percent, respectively, for February I, March I,
<br />and April 1. These forecasts were very accurate as actual runoff
<br />was 19,200 acre-feet and 40 percent of the recent l7-year average.
<br />With the low inflows to Willow Creek Reservoir, all available water
<br />(totaling 13,900 acre-feet) was pumped to Lake Granby during the
<br />summer season.
<br />
<br />As a result of near record-low inflows, the minimum releases from
<br />Lake Granby for "fish" requirements, as established by the Secretary
<br />of the Interior on January 19, 1961, were reduced to 70 percent of
<br />normal during the May-September period.
<br />
<br />In early April, the Directors of the Northern Colorado Conservancy
<br />District declared a 100 percent supplemental irrigation allotment.
<br />As a result, 294,400 acre-feet of water was diverted from Lake Granby
<br />via the Adams Tunnel to the eastern slope area of Colorado.
<br />
<br />On September 30, 1977, about 8,500 acre-feet were stored in Willow
<br />CreekReservoir which was slightly below a l7-year average of 9,100
<br />acre-feet.
<br />
<br />12
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