Upper Green River Basin (11)
June 1999

Snow
The Upper Green River Basin snow water equivalent (SWE), above Fontenelle Reservoir, is 146 percent of average (247 percent of last year). Cool weather has slowed the normal melting of snow -- consequently the comparison to average is exaggerated. The Green River basin SWE above Warren Bridge is 220 percent of normal (440 percent of last year). SWE on the West Side of the Upper Green River basin is about 140 percent of normal, 220 percent of this time last year. Newfork River SWE is now 111 percent of normal (Snow had all melted by this time last year). Big Sandy - Eden Valley SWE SNOTEL sites are is currently melted out. For more information see the Basin Summary of Snow Courses at the beginning of this report.

Precipitation
The 11 reporting precipitation sites in the basin were 111 percent of the May average (97 percent of last year at this time). May precipitation varied from 36 to 160 percent of average. Water year-to-date precipitation is about 104 percent of average (125 percent of last year). Year to date percentage of average ranges from 98 to 121 for the 11 reporting stations.

Reservoir
Big Sandy Reservoir is storing 40,300 acre-feet (142 percent of average and 105 percent of capacity). Eden reservoir is storing 8,500 acre-feet (109 percent of average and 72 percent of capacity). Fontenelle Reservoir is storing 206,000 acre-feet (105 percent of average and 60 percent of the total capacity). Flaming Gorge reservoir is presently storing about 3,236,995 acre-feet (reservoir capacity is 3,749,000 acre-feet). 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 310,000 acre-feet (117 percent of normal). Pine Creek above Fremont Lake is expected to yield 115,000 acre-feet (111 percent of normal). New Fork River near Big Piney is expected to yield about 450,000 acre-feet (117 percent of normal). Big Sandy near Farson is expected to be about 65,000 acre-feet (114 percent of normal). 

 
==================================================================================================================================
                                                     UPPER GREEN RIVER BASIN
                                               Streamflow Forecasts - June 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       275       296    |      310       117    |       324       345            266
                                                                    |                       |
Pine Creek abv Fremont Lake          APR-JUL       102       110    |      115       111    |       120       128            104
                                     JUN-JUL        79        89    |       95       112    |       102       111             85
                                                                    |                       |
New Fork River nr Big Piney          APR-JUL       385       424    |      450       117    |       476       515            385
                                                                    |                       |
Fontenelle Reservoir Inflow          APR-JUL       960      1042    |     1100       130    |      1159      1250            849
                                                                    |                       |
Big Sandy River nr Farson            APR-JUL        57        62    |       65       114    |        68        73             57
                                                                    |                       |
==================================================================================================================================
                         UPPER GREEN RIVER BASIN                        |                 UPPER GREEN RIVER BASIN
             Reservoir Storage (1000 AF) - End of May                   |        Watershed Snowpack Analysis - June 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     40.3     30.9     28.3 |   GREEN above Warren Bridge   4       440       220
                                                                        |
EDEN                                    11.8      8.5      5.7      7.8 |   UPPER GREEN (West Side)     5       220       140
                                                                        |
FLAMING GORGE                                   NO REPORT               |   NEWFORK RIVER               2         0       111
                                                                        |
FONTENELLE                             344.8    206.0    180.8    195.5 |   BIG SANDY/EDEN VALLEY       1         0         0
                                                                        |
                                                                        |   GREEN above Fontenelle     11       247       146
                                                                        |
==================================================================================================================================
 * 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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