Wyoming Water Supply Outlook Report
January 2001

Precipitation for December was generally below average for the State, with the exception of the Upper Green River and Lower North Platte River drainages. Year-to-date precipitation is below average for all except the Belle Fourche drainage. Reservoir levels vary from about 70 percent of average to 184 percent of average. Generally, the larger capacity reservoirs are above average storage. Forecast runoff varies from 60 to 103 percent of average. The mean of all the forecast points in the State is about 82 percent of average (18 percent below average).

Snowpack
Although the state received quite a bit of snow early, the snow fall did not carry through the early part of the winter. SWE is generally below average for the entire State. SWE in the northwestern portion of the State is now at 69 percent of average (101 percent of last year). Northeast Wyoming SWE is currently about 79 percent of average (102 percent of last year). The southeast portion is currently about 90 percent of average SWE (139 percent of last year). And the southwest is about 87 percent of average (149 percent of last year).

Precipitation
December precipitation was below normal over most of the State. Only the Lower North Platte and the Upper Green River drainage had above normal precipitation. The Belle Fourche drainage did receive a great deal of precipitation early in the fall, in the Black Hills region - further west in the drainage basin less precipitation was received. The following table displays the major river basins and their departure from normal for this month.

Streams
Stream flow yield is expected to be below average across the State. Most probable yield for the State is forecast to be about 83 percent of average (varies from 60 to 103 percent of average). The northwest part of the State is expected to yield about 77 percent of normal -- yield estimates vary from 60 to 90 percent of normal through the northwest region of the State. Yield from the northeast portion of Wyoming will be below average (about 74 percent of average) -- yield estimates vary from 70 to 78 percent of average for the various forecast points - this does not include the Belle Fourche drainage because data was missing and an estimate could not be prepared . The southeast portion of the state will be about 88 percent of normal -- yield estimates range from 81 to 103 percent of normal. The southwest portion of Wyoming varies from 72 to 100 percent of average -- mean estimated yield for the forecast points in southwest Wyoming is about 89 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 DECEMBER 2000


 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                 70          86          79          89          81
BELLE FOURCHE             74          97          51         146          76
BIG SANDY                                 NO REPORT
BIGHORN LAKE              65          71          66          99          92
BOYSEN                    77          92         103          75          84
BUFFALO BILL              59          71          68          87          83
BULL LAKE                 41          63          58          70          65
DEERFIELD                 99          97          81         122         101
EDEN                                      NO REPORT
FLAMING GORGE                       AVERAGE NOT ESTABLISHED
FONTENELLE                44          61          60          73          72
GLENDO                    47          55          55          86          86
GRASSY LAKE               83          80          69         120         103
GUERNSEY                  22          23          12         184          96
HEBGEN LAKE               79          91          65         120          86
JACKSON LAKE              75          75          56         136         101
KEYHOLE                   82          89          51         162          92
PACTOLA                   98          99          83         118          99
PALISADES                 41          84          74          56          49
PATHFINDER                69          91          50         139          75
PILOT BUTTE               75          73          49         152         103
SEMINOE                   71          83          53         132          85
SHADEHILL                 51          68          62          82          75
TONGUE RIVER              51          53          38         134          97
VIVA NAUGHTON RES         76           0          69         110           0
WHEATLAND #2                              NO REPORT
WOODRUFF NARROWS                    AVERAGE NOT ESTABLISHED
GLENDO PROJECT USERS      75          85          63         117          88
KENDRICK PROJECT          81          83          68         119          98
NORTH PLATTE PROJ         50          85          54          93          59