Wyoming Water Supply Outlook Report
January 2002

General
Generally, snow water equivalent (SWE) across the state is below normal for this time of the year. SWE averages for the State are about 77 percent of normal for this time of the year. Northwest portion of the State is 77 of percent normal. Northeast Wyoming is 66 of percent of normal, and the southeast part of the State is 66 percent of average. Southwestern Wyoming is 85 percent of average for this time of the year.

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.

BasinDeparture
from normal
BasinDeparture
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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