Precipitation for December was generally below average for the State, with the exception of the Green River and Bear River drainages. Year-to-date precipitation is below average for the year. Reservoir levels vary from below average to average. With the exception of the northeast, large capacity reservoirs are average to below average. Reservoirs in the northeast have above average storage. Generally, forecast runoff varies from 37 to 86 percent of average.
Snowpack
Although the state received quite a bit of snow early this fall, little snowfall has occurred this past month. SWE is generally below average for the entire State. SWE in the northwestern portion of the State is now at 80 percent of average (122 percent of last year). Northeast Wyoming SWE is currently about 77 percent of average (100 percent of last year). The southeast portion is currently about 85 percent of average SWE (71 percent of last year). And the southwest is about 85 percent of average (101 percent of last year).
Precipitation
December precipitation was below normal over most of the State. Only the Green River and Bear River drainage had above normal precipitation, and that was just barely above normal. Some of the State had a very severe shortage of precipitation. The following table displays the major river basins and their departure from normal for this month.
| Basin | Departure from normal | Basin | Departure from normal |
| Snake River | -01% | Upper North Platte River | -30% |
| Yellowstone & Madison | -06% | Lower North Platte River | -51% |
| Wind River | -15% | Little Snake River | -21% |
| Bighorn | -56% | Upper Green River | +04% |
| Shoshone & Clarks Fork | -32% | Lower Green River | +05% |
| Powder & Tongue River | -54% | Upper Bear River | +01% |
| Belle Fourche & Cheyenne | -80% |
Streams
Stream flow yield is expected to be below average across the State. Most probable yield for the State is forecast to be about 62 percent of average (varies from 37 to 86 percent of average). The northwest part of the State is expected to yield about 60 percent of normal -- yield estimates vary from 43 to 81 percent of normal. Yield from the northeast portion of Wyoming will be below average (about 50 percent of average) -- yield estimates vary from 37 to 63 percent of average for the various forecast points. The southeast portion of the state will be about 55 percent of normal -- yield estimates range from 37 to 77 percent of normal. The southwest portion of Wyoming varies from 61 to 86 percent of average -- mean estimated yield for the forecast points in southwest Wyoming is about 75 percent of average.
Reservoirs
B A S I N W I D E
R E S E R V O I R S U M M A R Y
FOR THE END OF DECEMBER 2001
BASIN AREA CURRENT AS LAST YR AS AVERAGE AS CURRENT AS CURRENT AS
RESERVIOR CAPACITY % CAPACITY % CAPACITY % AVERAGE % LAST YR
------------- --------- --------- --------- --------- ---------
ALCOVA 85 85 84 101 100
ANGOSTURA 80 70 79 101 115
BELLE FOURCHE 70 74 51 138 94
BIG SANDY 9 13 48 20 71
BIGHORN LAKE 56 65 67 83 85
BOYSEN 14 77 104 13 18
BUFFALO BILL 36 59 46 78 62
BULL LAKE 19 41 57 33 45
DEERFIELD 98 99 81 121 99
EDEN 4 0 31 13 0
ENNIS LAKE 75 75 77 97 100
FLAMING GORGE 77 80 78 98 96
FONTENELLE 42 44 61 70 96
GLENDO 38 47 56 68 81
GRASSY LAKE 61 83 76 79 73
GUERNSEY 24 22 16 153 109
HEBGEN LAKE 78 79 71 111 100
JACKSON LAKE 16 75 57 29 22
KEYHOLE 80 82 52 152 97
PACTOLA 95 98 83 114 97
PALISADES 31 41 74 42 76
PATHFINDER 48 69 63 77 70
PILOT BUTTE 80 75 64 125 107
SEMINOE 47 71 62 76 67
SHADEHILL 65 51 62 104 127
TONGUE RIVER 26 44 28 92 59
VIVA NAUGHTON RES 68 76 75 92 90
WHEATLAND #2 19 0 43 45 0
WOODRUFF NARROWS NO REPORT
GLENDO PROJECT USERS 74 75 63 116 99
KENDRICK PROJECT 69 81 68 101 85
NORTH PLATTE PROJ 25 50 54 46 49
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