Wyoming Water Supply Outlook Report
June 1997

General
Water conditions across Wyoming are very good. May precipitation varied quite a bit across the state. Snow melt in all the basins is ahead of average for this time of year. This, coupled with record snow levels, is resulting in very high runoff figures. Precipitation for the year is also very high across the State with all areas above average for the year. Reservoir storage is looking very good across the State also, although most reservoirs have been drawn down to make room for the runoff.

Snowpack
Snowpack over the State was above normal to much above normal most of the snow season. Some basins remain at record levels, especially the Snake, Madison, Shoshone, and Yellowstone River basins. Generally, all the low elevation snow has melted out -- melt out seems to have occurred slightly earlier than normal. Snow at the higher levels is anticipated to melt out at a normal to above normal rate.

Precipitation
Basins across Wyoming received a mixed bag as far as May precipitation is concerned. The Lower Green received only 66 percent of average during the month. Eight of the 13 basins were below average for the month. Year to date figures are much higher with percentages ranging from 106 percent on the Powder to 157 in the Belle Fourche. The following table displays the major river basins and their departure from normal. 


Basin                 Departure    Basin                   Departure
                    from normal                          from normal

Snake River                +33%    Upper North Platte River     +24%
Yellowstone & Madison      +49%    Lower North Platte           +18%
Wind River                 +22%    Little Snake River           +15%
Big Horn                   +07%    Upper Green River            +17%
Shoshone & Clarks Fork     +41%    Lower Green River            +24%
Powder & Tongue River      +06%    Upper Bear River             +36%
Belle Fourche & Cheyenne   +57%
Streams
All basins in the State should see average or above average runoff -- in some cases there will be much above average yield. Record SWE was recorded in most parts of the State during much of the snow season. High runoff might be expected in portions of Wyoming. Under the right conditions exceptionally high flows could occur in the areas with record snow levels. Water users should not expect any shortages during the irrigation season.

Reservoirs
Reservoir storage varies from well below to well above average. Most reservoirs should fill to capacity this year. Many reservoirs were lowered significantly in anticipation of excessive flows during the runoff season -- those reservoirs are presently being filled.. 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   MAY    1997


BASIN AREA         CURRENT AS  LAST YR AS  AVERAGE AS  CURRENT AS  CURRENT AS
RESERVOIR         % CAPACITY  % CAPACITY  % CAPACITY   % AVERAGE   % LAST YR
------------------------------------------------------------------------------
ALCOVA                    98          97          98         100         101
ANGOSTURA                 99         100          96         103          99
BELLE FOURCHE            105         110          85         123          95
BIG SANDY                105          86          74         142         122
BIGHORN LAKE                              NO REPORT
BOYSEN                    71          76          92          77          93
BUFFALO BILL              52          54          58          89          97
BULL LAKE                 64          57          61         105         113
DEERFIELD                 99         101          89         111          98
EDEN                     103          55          66         156         188
ENNIS LAKE                                NO REPORT
FONTENELLE                62          38          57         109         163
GLENDO                   100         105          99         101          95
GRASSY LAKE               99          98          89         111         101
GUERNSEY                  77          80          76         102          96
HEBGEN LAKE                               NO REPORT
JACKSON LAKE              85          79          64         133         108
KEYHOLE                   95          79          59         162         120
PACTOLA                  101         106          88         115          95
PALISADES                 66          50          75          87         132
PATHFINDER                94          94          63         150         100
PILOT BUTTE               70          61          81          87         114
SEMINOE                   77          77          54         143         101
SHADEHILL                 82          89          84          97          92
TONGUE RIVER              46          54          71          65          85
VIVA NAUGHTON RES         94          88          80         117         107
WHEATLAND #2              64          67          55         115          95
WOODRUFF NARROWS                          NO REPORT
GLENDO PROJECT USERS      90          94          82         110          96
KENDRICK PROJECT          85          85          70         121         100
NORTH PLATTE PROJ         99          99          86         116         100
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