Upper Green River Basin
February 1997

Snow
Snowpack in the basin, as of February 1, is 174 percent of average. Snow Water Equivalent (SWE) for the Green River above Warren Bridge is 165 percent of average and 20 percent more than last year. SWE on the west side of the Upper Green River basin is about 77 percent more than normal, 19 percent more than last year. SWE in the New Fork drainage is 75 percent more than normal, which is about 51 percent more than last year. For more information see the Basin Summary of Snow Courses at the beginning of this report.

Precipitation
The 13 reporting precipitation sites in the basin averaged 91 percent of average for January. January precipitation varied from 70 percent below normal (Loomis Park) to 229 percent above normal (Fontenelle Dam). Water year-to-date precipitation, is 39 percent above normal (22 percent more than last year).

Reservoir
Fontenelle is the only reporting reservoir this month. Storage in Fontenelle is currently 149,600 acre feet (76 percent of average). Detailed reservoir data is shown on the following page and on the reservoir storage summary at the beginning of this report.

Streamflow
Runoff yield in the basin is forecast above average to much above average. The fifty percent chance April through July runoff at Green River at Warren Bridge is expected to yield about 350,000 acre feet (32 percent more than normal). Pine Creek above Fremont Lake is expected to yield 145,000 acre feet or 45 percent more than normal. New Fork River near Big Piney has a 50 percent chance yield of 550,000 acre feet or 43 percent more than normal. The 50 percent chance inflow to Fontenelle Reservoir is about 1,250,000 acre feet, which is about 47 percent more than normal. Big Sandy near Farson is expected to be about 80,000 acre feet (40 percent more than normal). 

==================================================================================================================================
                                                     UPPER 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 at Warren Bridge             APR-JUL       319       348    |      375       141    |       402       431            266
                                                                    |                       |
PINE CK abv Fremont Lake             APR-JUL       119       134    |      140       135    |       146       161            104
                                                                    |                       |
NEW FORK R nr Big Piney              APR-JUL       404       512    |      550       143    |       588       697            385
                                                                    |                       |
FONTENELLE RESERVOIR INFLOW          APR-JUL       976      1157    |     1250       147    |      1343      1520            849
                                                                    |                       |
BIG SANDY R nr Farson                APR-JUL        61        73    |       80       140    |        87        99             57
                                                                    |                       |
==================================================================================================================================
                         UPPER GREEN RIVER BASIN                        |                 UPPER 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
========================================================================|=========================================================
BIG SANDY                                       NO REPORT               |   GREEN above Warren Bridge   4       120       165
                                                                        |
EDEN                                            NO REPORT               |   UPPER GREEN (West Side)     7       119       177
                                                                        |
FLAMING GORGE                         3749.0   3215.6   3230.9      --- |   NEWFORK RIVER               3       151       175
                                                                        |
FONTENELLE                             344.8    149.6    163.8    196.2 |   BIG SANDY/EDEN VALLEY       2       143       177
                                                                        |
                                                                        |   GREEN above Fontenelle     14       123       174
                                                                        |
==================================================================================================================================
 * 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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