Precipitation for May was average to above average for the State, with the exception of the Belle Fourche and Little Snake River drainages, - - the year-to-date precipitation is near average to below average. Most of the reservoir levels are average to well above average. Forecast runoff varies from 34 to 99 percent of average. The mean of all the forecast points in the State is about 65 percent of average (35 percent below average). The minimum yield forecast was 34 percent of average in the Middle PoPo Agie River near Lander and the maximum forecast was 99 percent of average at Deer Creek at Glenrock.
Snowpack
The early warm weather has resulted in more snow melting than is
normal for this time of the year. SWE is generally well below average
for the entire State. SWE in the northwestern portion of the State is
now at 42 percent of average (27 percent of last year). Northeast
Wyoming SWE is currently about 48 percent of average (33 percent of
last year). The Southeast portion saw a decrease to 32 percent of
average SWE (27 percent of last year). And the southwest dropped to
about 18 percent of average (11 percent of last year).
Precipitation
May precipitation was slightly above normal across most of the State.
The Belle Fourche and Little Snake River drainage's were below normal,
and the Big horn and Upper Green River drainage's were near normal.
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 | +18% | Upper North Platte River | +23% |
| Yellowstone & Madison | +54% | Lower North Platte River | +27% |
| Wind River | +06% | Little Snake River | -09% |
| Bighorn | 0% | Upper Green River | 0% |
| Shoshone & Clarks Fork | +24% | Lower Green River | +02% |
| Powder & Tongue River | +26% | Upper Bear River | +12% |
| Belle Fourche & Cheyenne | -05% |
Streams
Stream flow yield is expected to be well below average across the
State. Yield for the State is forecast to be about 65 percent of
average. The northwest part of the State is expected to yield about
66 percent of normal -- yield estimates vary from 34 to 86 percent of
normal through the northwest region of the State. Yield from the
northeast portion of Wyoming will be below average (about 65 percent
of average) -- yield estimates vary from 52 to 82 percent of average
for the various forecast points. In most cases, the southeast portion
of the state will be about 66 percent of normal -- yield estimates
range from 38 to 99 percent of normal. The southwest portion of
Wyoming varies from 47 to 77 percent of average -- mean estimated
yield for the forecast points in southwest Wyoming is about 62 percent
of average.
Reservoirs
Although several reservoirs did not report, reservoir storage for
those reporting 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 MAY 2000
BASIN AREA CURRENT AS LAST YR AS AVERAGE AS CURRENT AS CURRENT AS
RESERVIOR % CAPACITY % CAPACITY % CAPACITY % AVERAGE % LAST YR
------------------------------------------------------------------------------
--
ALCOVA 98 97 98 100 101
ANGOSTURA 98 99 96 102 99
BELLE FOURCHE 107 105 85 125 102
BIG SANDY NO REPORT
BIGHORN LAKE 70 67 63 111 104
BOYSEN 91 82 92 99 111
BUFFALO BILL 78 61 58 134 129
BULL LAKE 74 62 61 122 120
DEERFIELD 99 100 89 111 99
EDEN NO REPORT
FLAMING GORGE NO REPORT
FONTENELLE 54 60 57 96 91
GLENDO 100 109 99 101 92
GRASSY LAKE 94 89 89 105 105
GUERNSEY 79 74 76 104 106
HEBGEN LAKE 94 79 82 115 119
JACKSON LAKE 100 76 64 156 131
KEYHOLE 91 93 59 155 98
PACTOLA 99 100 88 113 100
PALISADES 95 52 75 125 183
PATHFINDER 98 98 63 156 100
PILOT BUTTE 78 53 81 96 148
SEMINOE 90 83 54 166 108
SHADEHILL 69 96 84 82 72
TONGUE RIVER 117 96 71 165 122
VIVA NAUGHTON RES 107 81 80 133 132
WHEATLAND #2 82 91 55 148 90
WOODRUFF NARROWS NO REPORT
GLENDO PROJECT USERS 94 94 82 115 100
KENDRICK PROJECT 87 87 70 124 100
NORTH PLATTE PROJ 100 100 86 117 100
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