Snowpack
April Conditions varied across the State. Substantial precipitation
did occur toward the end of April. SWE, in the northwest and western
portions of the State, increased significantly. More than 50 inches of
snow was measured at the lower elevations of the Wind River drainage.
The Shoshone and Upper Yellowstone Basins remain well above average.
Snow water equivalents (SWE) in the southern and eastern areas of
Wyoming vary from slightly below average to above average. The
comparison to average conditions, across the state, increased in
percentage for all except the Belle Fourche drainage.
Precipitation
All the basins, except one, received above average precipitation for
the month of April. Most basins received well above average
precipitation for the month of April. The following table displays
the major river basins and their departure from normal for April 1999.
| Basin | Departure from normal | Basin | Departure from normal |
| Snake River | +31% | Upper North Platte River | +53% |
| Yellowstone & Madison | +15% | Lower North Platte River | +88% |
| Wind River | +202% | Little Snake River | +34% |
| Bighorn | +78% | Upper Green River | +84% |
| Shoshone & Clarks Fork | +49% | Lower Green River | +165% |
| Powder & Tongue River | +89% | Upper Bear River | +63% |
| Belle Fourche & Cheyenne | -08% |
Streams
Runoff is expected to vary greatly across the state. Yield from the
northeast portion of Wyoming should be near average -- yield estimates
vary from 88 to 111 percent of average (mean is 100%). In most cases,
the southeast portion of the state will be about 10 percent above
normal -- yield estimates range from 88 to 246 percent of normal. The
southwest portion of Wyoming varies from 93 to 121 percent of average
-- mean estimated yield for southeast Wyoming is 110 percent of
average. The northwest part of the State is expected to yield about
24 percent more than normal -- yields vary from 75 to 163 percent of
normal.
Reservoirs
Reservoir storage is generally above average for this time of the
year. See following table for further information about reservoir
storage.
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 APRIL 1999
BASIN AREA CURRENT AS LAST YR AS AVERAGE AS CURRENT AS CURRENT AS
RESERVIOR % CAPACITY % CAPACITY % CAPACITY % AVERAGE % LAST YR
------------------------------------------------------------------------------
ALCOVA 97 97 98 99 100
ANGOSTURA 99 99 93 107 100
BELLE FOURCHE 103 103 82 126 99
BIG SANDY 99 75 62 158 132
BIGHORN LAKE 57 61 58 98 93
BOYSEN 80 76 84 94 105
BUFFALO BILL 56 76 52 108 73
BULL LAKE 66 63 53 125 104
DEERFIELD 101 96 89 112 105
EDEN 72 44 50 144 163
ENNIS LAKE 81 80 86 95 101
FLAMING GORGE AVERAGE NOT ESTABLISHED
FONTENELLE 39 38 47 83 102
GLENDO 104 94 90 115 111
GRASSY LAKE 88 49 77 115 179
GUERNSEY 82 70 72 113 117
HEBGEN LAKE 61 70 65 93 87
JACKSON LAKE 63 78 54 117 80
KEYHOLE 96 93 57 170 103
PACTOLA 101 98 87 116 104
PALISADES 40 65 68 58 61
PATHFINDER 98 97 60 163 101
PILOT BUTTE 61 78 95 64 78
SEMINOE 71 68 39 184 104
SHADEHILL 96 89 80 119 108
TONGUE RIVER 40 15 54 75 273
VIVA NAUGHTON RES 69 72 62 110 96
WHEATLAND #2 77 80 56 138 96
WOODRUFF NARROWS AVERAGE NOT ESTABLISHED
GLENDO PROJECT USERS 94 91 70 134 103
KENDRICK PROJECT 86 80 67 128 108
NORTH PLATTE PROJ 100 104 74 135 96
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