Snowpack
Conditions vary considerably across the State as of January 1. The
northwest and western portions of the State are near average to a
little above average. The southern and eastern areas of Wyoming are
below to well below average in percent of normal snow water equivalent
(SWE). The Shoshone and Upper Yellowstone Basins are well above
average while the Belle Fourche, Little Snake, and Platte River basins
are well below average for this time of year. The Bighorn River basin
is a little above average, while on the other side of the Bighorn
Mountains, the Powder-Tongue River basin is well below average.
Precipitation
Most basins across Wyoming received below average precipitation for
the month of December. Ten of the 13 basins were below average for the
month. The following table displays the major river basins and their
departure from normal for December 1998.
Basin | Departure from normal | Basin | Departure from normal |
Snake River | -15% | Upper North Platte River | -38% |
Yellowstone & Madison | +03% | Lower North Platte River | -28% |
Wind River | -23% | Little Snake River | -35% |
Bighorn | -02% | Upper Green River | -17% |
Shoshone & Clarks Fork | +25% | Lower Green River | -29% |
Powder & Tongue River | +02% | Upper Bear River | -28% |
Belle Fourche & Cheyenne | -25% |
Streams Runoff is expected to vary greatly across the state. The northwestern part of the state is expected to have yields varying from average to slightly above average. The northeast portion of Wyoming should be well above average. This is due to very high precipitation during the early part of the water year (Oct-Sep). In most cases, the southeast portion of the state will vary from 20 to 60 percent below normal (as much as 60 percent below normal in the LaPrele Creek drainage). The southwest portion of Wyoming varies from near average to 25 percent below average on the Green River drainage, while the Bear River will produce 15-30 percent below average yields.
Reservoirs
Reservoir storage is average to well above average for this time of
the year. See following table for further information about reservoir
storage.
Major Reservoirs in Wyoming
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 1998 BASIN AREA CURRENT AS LAST YR AS AVERAGE AS CURRENT AS CURRENT AS RESERVIOR % CAPACITY % CAPACITY % CAPACITY % AVERAGE % LAST YR ------------------------------------------------------------------------------ ALCOVA 85 85 83 102 100 ANGOSTURA 91 92 79 115 98 BELLE FOURCHE 93 92 51 184 102 BIG SANDY 81 55 45 179 146 BIGHORN LAKE 70 71 66 106 98 BOYSEN 100 95 103 97 104 BUFFALO BILL 69 84 68 103 82 BULL LAKE 65 64 58 110 101 DEERFIELD 94 101 81 116 93 EDEN NO REPORT ENNIS LAKE 82 73 82 100 112 FLAMING GORGE AVERAGE NOT ESTABLISHED FONTENELLE 66 65 60 109 102 GLENDO 69 72 55 126 95 GRASSY LAKE 83 54 69 120 154 GUERNSEY 31 28 12 260 112 HEBGEN LAKE 88 76 65 134 116 JACKSON LAKE 70 76 56 125 92 KEYHOLE 91 89 51 180 102 PACTOLA 94 95 83 112 98 PALISADES 86 93 74 117 92 PATHFINDER 86 91 50 172 95 PILOT BUTTE 72 71 49 146 102 SEMINOE 74 86 53 140 86 SHADEHILL 71 68 62 114 104 TONGUE RIVER 9 9 38 22 97 VIVA NAUGHTON RES NO REPORT WHEATLAND #2 AVERAGE NOT ESTABLISHED WOODRUFF NARROWS AVERAGE NOT ESTABLISHED GLENDO PROJECT USERS 85 84 63 135 101 KENDRICK PROJECT 82 84 68 120 98 NORTH PLATTE PROJ 76 89 54 142 85