Upper Green River Basin (11)
March 1999

Snow
The Upper Green River Basin snow water equivalent (SWE), above Fontenelle Reservoir, is 112 percent of average (138 percent of last year). The Green River above Warren Bridge is 111 percent of normal (133 percent of last year). SWE on the west side of the Upper Green River basin is about 113 percent of normal, 139 percent of this time last year. Newfork River is now 112 percent of normal, 144 percent of last year. Big Sandy - Eden Valley is currently 115 percent of normal (172 percent of last year). For more information see the Basin Summary of Snow Courses at the beginning of this report.

Precipitation
The 12 reporting precipitation sites in the basin were 158 percent of average for February; precipitation was 323 percent of last year at this time. February precipitation varied from 113 to 219 percent. Water year- to-date precipitation is about 98 percent of average (139 percent of last year). Year to date percentages range from 87 to 122.

Reservoir
Big Sandy Reservoir is storing 31,100 acre-feet (180 percent of average and 86 percent of capacity). Eden reservoir did not report. Fontenelle Reservoir is storing 144,800 acre-feet (84 percent of average and 42 percent of the total capacity). 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 above average. Green River at Warren Bridge is expected to yield about 285,000 acre-feet (107 percent of normal). Pine Creek above Fremont Lake is expected to yield 110,000 acre-feet (106 percent of normal). New Fork River near Big Piney is expected to yield about 440,000 acre-feet (114 percent of normal). Inflow to Fontenelle Reservoir is expected to be about 950,000 acre feet (112 percent of average). Big Sandy near Farson is expected to be about 63,000 acre-feet (111 percent of normal). 

 
==================================================================================================================================
                                                     UPPER GREEN RIVER BASIN
                                               Streamflow Forecasts - March 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       234       261    |      285       107    |       309       335            266
                                                                    |                       |
Pine Creek abv Fremont Lake          APR-JUL        92       103    |      110       106    |       117       128            104
                                                                    |                       |
New Fork River nr Big Piney          APR-JUL       320       397    |      440       114    |       483       558            385
                                                                    |                       |
Fontenelle Reservoir Inflow          APR-JUL       679       866    |      950       112    |      1038      1223            849
                                                                    |                       |
Big Sandy River nr Farson            APR-JUL        47        56    |       63       111    |        70        79             57
                                                                    |                       |
==================================================================================================================================
                         UPPER GREEN RIVER BASIN                        |                 UPPER GREEN RIVER BASIN
             Reservoir Storage (1000 AF) - End of February              |        Watershed Snowpack Analysis - March 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     33.1     23.9     18.4 |   GREEN above Warren Bridge   4       133       111
                                                                        |
EDEN                                            NO REPORT               |   UPPER GREEN (West Side)     7       139       113
                                                                        |
FLAMING GORGE                         3749.0   3265.3   3247.0      --- |   NEWFORK RIVER               3       144       112
                                                                        |
FONTENELLE                             344.8    144.8    134.2    172.0 |   BIG SANDY/EDEN VALLEY       2       172       115
                                                                        |
                                                                        |   GREEN above Fontenelle     14       138       112
                                                                        |
==================================================================================================================================
 * 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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