Lower Green River Basin
February 1997

Snow
The Blacks Fork drainage snow water equivalent (SWE) is 139 percent of average, currently the lowest in the basin. Henrys Fork is about 167 percent of average. Snowpack in the Hams Fork, as of February 1, is 184 percent of average. The basin as a whole is 173 percent of average. This is 24 percent ahead of last year at this time. For more information see Basin Summary of Snow Courses at beginning of this report.

Precipitation
Precipitation was heavy throughout the basin during January. Precipitation ranged from 124 percent of average at Kelley RS to 198 percent of average at Rock Springs. The entire basin received 135 percent of average for the month (91 percent of last year). The basin year to date precipitation is currently 155 percent of average; sites range from 133 to 189 percent of average.

Reservoir
Fontenelle Reservoir is currently storing 149,600 acre feet; this is 76 percent of average storage. Viva Naughton currently is storing 27,100 acre feet; 94 percent of average. Flaming Gorge did not report.

Streamflow
Water users can expect above average yields in the basin this season. The following forecast values are based on a 50 percent chance probability for the April to July forecast period. Yields will range from 141 percent of average for Meeks Cabin Reservoir inflow (135,000 acre feet) to 197 percent of average (130,000 acre feet) at Hams Fork near Frontier. Green River near Green River is forecast to yield 1,300,000 acre feet (145 percent of average). State Line Reservoir inflow is estimated to flow 50,000 acre feet (167 percent of average). Viva Naughton Reservoir inflow will be about 180,000 acre feet (194 percent of average). Flaming Gorge Reservoir inflow should be near 1,800,000 acre feet (151 percent of average. 

==================================================================================================================================
                                                     LOWER GREEN RIVER BASIN
                                               Streamflow Forecasts - February 1, 1997
==================================================================================================================================
                                              |  <<====== Drier ======  Future Conditions  =======  Wetter =====>>  |             
                                              |                                                                     |
  Forecast Point                     Forecast |  ==================== Chance Of Exceeding * ======================  |
                                      Period  |    90%       70%    |  50% (Most Probable)  |      30%       10%    |  30-Yr Avg.
                                              | (1000AF)  (1000AF)  |   (1000AF)  (% AVG.)  |    (1000AF)  (1000AF) |    (1000AF)
====================================================================|=======================|=====================================
GREEN R nr Green River, WY           APR-JUL      1007      1207    |     1300       145    |      1393      1591            899
                                                                    |                       |
MEEKS CABIN RESERVOIR Inflow         APR-JUL       109       124    |      135       141    |       146       161             96
                                                                    |                       |
STATE LINE RESERVOIR INFLOW          APR-JUL        40        46    |       50       167    |        54        60             30
                                                                    |                       |
HAMS FORK nr Frontier                APR-JUL       105       120    |      130       197    |       140       155             66
                                                                    |                       |
VIVA NAUGHTON RES inflow             APR-JUL       146       166    |      180       194    |       194       214             93
                                                                    |                       |
FLAMING GORGE RES INFLOW             APR-JUL      1351      1655    |     1800       151    |      1945      2248           1196
                                                                    |                       |
==================================================================================================================================
                         LOWER GREEN RIVER BASIN                        |                 LOWER GREEN RIVER BASIN
             Reservoir Storage (1000 AF) - End of January               |        Watershed Snowpack Analysis - February 1, 1997
==================================================================================================================================
                                      Usable |  *** Usable Storage ***  |                            Number     This Year as % of
Reservoir                            Capacity|  This      Last          |   Watershed                  of       =================
                                             |  Year      Year     Avg  |                          Data Sites   Last Yr   Average
========================================================================|=========================================================
FONTENELLE                             344.8    149.6    163.8    196.2 |   HAMS FORK RIVER             4       128       184
                                                                        |
FLAMING GORGE                         3749.0   3215.6   3230.9      --- |   BLACKS FORK                 2        96       139
                                                                        |
VIVA NAUGHTON RES                       42.4     27.1     33.6     28.7 |   HENRYS FORK                 2       160       167
                                                                        |
                                                                        |   GREEN above Flaming Gorge  22       124       173
                                                                        |
==================================================================================================================================
 * 90%, 70%, 30%, and 10% chances of exceeding are the probabilities that the actual flow will exceed the volumes in the table.

The average is computed for the 1961-1990 base period.

(1) - The values listed under the 10% and 90% Chance of Exceeding are actually 5% and 95% exceedance levels.                  
(2) - The value is natural flow - actual flow may be affected by upstream water management.
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