Upper Green River Basin (11)
February 1999

Snow
The Upper Green River Basin snow water equivalent (SWE), above Fontenelle Reservoir, is 94 percent of average (105 percent of last year). The Green River above Warren Bridge is 93 percent of normal (102 percent of last year). SWE on the west side of the Upper Green River basin is about 91 percent of normal, 101 percent of this time last year. Newfork River is now 105 percent of normal, 128 percent of last year. The Big Sandy - Eden Valley is currently 99 percent of normal (146 percent of 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 were 84 percent of average for January; precipitation was 64 percent of last year at this time. January precipitation varied from 55 to 103 percent. Water year-to-date precipitation is about 85 percent of average (112 percent of last year). Year to date percentages range from 76 to 124.

Reservoir
Big Sandy Reservoir is storing 30,900 acre-feet (174 percent of average and 81 percent of capacity). Eden reservoir did not report. Fontenelle Reservoir is storing 180,900 acre-feet (92 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
The fifty percent chance April through July runoff in the Upper Green River basin is forecast below average. Green River at Warren Bridge is expected to yield about 260,000 acre-feet (98 percent of normal). Pine Creek above Fremont Lake is expected to yield 100,000 acre-feet (96 percent of normal). New Fork River near Big Piney is expected to yield about 390,000 acre-feet (101 percent of normal). Big Sandy near Farson is expected to be about 60,000 acre-feet (105 percent of normal). 

==================================================================================================================================
                                                     UPPER GREEN RIVER BASIN
                                               Streamflow Forecasts - February 1, 1999
==================================================================================================================================
                                              |  <<====== 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 River at Warren Bridge         APR-JUL       205       235    |      260        98    |       285       314            266
                                                                    |                       |
Pine Creek abv Fremont Lake          APR-JUL        79        93    |      100        96    |       107       121            104
                                                                    |                       |
New Fork River nr Big Piney          APR-JUL       246       340    |      390       101    |       440       535            385
                                                                    |                       |
Big Sandy River nr Farson            APR-JUL        42        53    |       60       105    |        67        78             57
                                                                    |                       |
==================================================================================================================================
                         UPPER GREEN RIVER BASIN                        |                 UPPER GREEN RIVER BASIN
             Reservoir Storage (1000 AF) - End of January               |        Watershed Snowpack Analysis - February 1, 1999
==================================================================================================================================
                                      Usable |  *** Usable Storage ***  |                            Number     This Year as % of
Reservoir                            Capacity|  This      Last          |   Watershed                  of       =================
                                             |  Year      Year     Avg  |                          Data Sites   Last Yr   Average
========================================================================|=========================================================
BIG SANDY                               38.3     30.9     22.9     17.8 |   GREEN above Warren Bridge   4       102        93
                                                                        |
EDEN                                            NO REPORT               |   UPPER GREEN (West Side)     7       101        91
                                                                        |
FLAMING GORGE                         3749.0   3341.0   3279.0      --- |   NEWFORK RIVER               3       128       105
                                                                        |
FONTENELLE                             344.8    180.9    176.1    196.2 |   BIG SANDY/EDEN VALLEY       2       146        99
                                                                        |
                                                                        |   GREEN above Fontenelle     14       105        94
                                                                        |
==================================================================================================================================
 * 90%, 70%, 30%, and 10% chances of exceeding are the probabilities that the actual volume 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 volume - actual volume may be affected by upstream water management.
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