Upper Green River Basin (11)
February 1998

Snow
Upper Green River Basin snow water equivalent (SWE),above Fontenelle Reservoir, is 88 percent of average (50 percent of last year). SWE for the Green River above Warren Bridge is 84 percent of average and 46 percent of last year at this time. SWE on the west side of the Upper Green River basin is about 91 percent of normal, 52 percent of this time last year. Newfork River SWE is about 82 percent of normal - about 47 percent of last year at this time. SWE for Big Sandy - Eden Valley area is 67 percent of normal and 38 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 132 percent of average for January; precipitation was 141 percent of last year at this time. January precipitation varied from 7 percent of normal (Farson) to 167 percent above normal (Kendall RS SNOTEL). Water year-to-date precipitation is about 26 percent below normal (52 percent of last year).

Reservoir
Big Sandy Reservoir is storing 22,900 acre feet (129 percent of average) and Eden is storing 3,500 acre feet (85 percent of average). Fontenelle Reservoir is about 90 percent of average (176,100 acre feet). Flaming Gorge reservoir contains about 3,279,000 acre feet this year compared to 3,365,200 acre feet last year. 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 basin, is forecast below average. Green River at Warren Bridge is expected to yield about 225,000 acre feet (85 percent of normal). Pine Creek above Fremont Lake is expected to yield 95,000 acre feet ( 91 percent of normal). New Fork River near Big Piney is expected to yield about 325,000 acre feet (84 percent of normal). The 50 percent chance inflow to Fontenelle Reservoir is about 685,000 acre feet, which is about 81 percent of normal. Big Sandy near Farson is expected to be about 45,000 acre feet (79 percent of normal). 

==================================================================================================================================
                                                     UPPER GREEN RIVER BASIN
                                               Streamflow Forecasts - February 1, 1998
==================================================================================================================================
                                              |  <<====== 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       170       198    |      225        85    |       252       279            266
                                                                    |                       |
PINE CK abv Fremont Lake             APR-JUL        74        89    |       95        91    |       101       116            104
                                                                    |                       |
NEW FORK R nr Big Piney              APR-JUL       181       287    |      325        84    |       363       470            385
                                                                    |                       |
FONTENELLE RESERVOIR INFLOW          APR-JUL       416       592    |      685        81    |       778       951            849
                                                                    |                       |
BIG SANDY R nr Farson                APR-JUL        29        38    |       45        79    |        52        61             57
                                                                    |                       |
==================================================================================================================================
                         UPPER GREEN RIVER BASIN                        |                 UPPER GREEN RIVER BASIN
             Reservoir Storage (1000 AF) - End of January               |        Watershed Snowpack Analysis - February 1, 1998
==================================================================================================================================
                                      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     22.9      ---     17.8 |   GREEN above Warren Bridge   4        46        84
                                                                        |
EDEN                                    11.8      3.5      ---      4.1 |   UPPER GREEN (West Side)     7        52        91
                                                                        |
FONTENELLE                             344.8    176.1    149.6    196.2 |   NEWFORK RIVER               3        47        82
                                                                        |
                                                                        |   BIG SANDY/EDEN VALLEY       2        38        67
                                                                        |
                                                                        |   GREEN above Fontenelle     14        50        88
                                                                        |
==================================================================================================================================
 * 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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