Lower Green River Basin (12)
January 1998

Snow
The Blacks Fork drainage snow water equivalent (SWE) is 94 percent of average (70 % of last year). Henry's Fork is 192 percent of the January 1 average (124 % of last year). SWE in the Hams Fork, as of January 1, is 58 percent of average (27 % of last year). The basin as a whole is 63 percent of average (31 % of last year). For more information see Basin Summary of Snow Courses at beginning of this report.

Precipitation
Precipitation was below average throughout the basin during December. Precipitation ranged from 32 to 144 percent of average from the 4 reporting stations. The entire basin received 45 percent of average for the month (19 percent of last year). The basin year-to-date precipitation is currently 50 percent of average (31 % of last year).

Reservoir
Fontenelle Reservoir is currently storing 223,100 acre feet; this is 107 percent of average storage (20 % more than last year). Flaming Gorge and Viva Naughton did not report this month.

Streamflow
Water users can expect below average yields in the basin this season. The following forecast values are based on a 50 percent chance probability for the April to July forecast period. Yields will be 80 percent of average for State Line Reservoir inflow (24,000 acre feet) and 68 percent of average (45,000 acre feet) at Hams Fork near Frontier. Green River near Green River is forecast to yield 485,000 acre feet (54 percent of average). Meeks Cabin Reservoir inflow is estimated to flow 80,000 acre feet (83 percent of average). Viva Naughton Reservoir inflow will be about 59,000 acre feet (63 percent of average). Flaming Gorge Reservoir inflow should be near 675,000 acre feet (56 percent of average). 

==================================================================================================================================
                                                     LOWER GREEN RIVER BASIN
                                               Streamflow Forecasts - January 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 nr Green River, WY           APR-JUL       344       369    |      485        54    |       601       771            899
                                                                    |                       |
MEEKS CABIN RESERVOIR Inflow         APR-JUL        52        69    |       80        83    |        91       108             96
                                                                    |                       |
STATE LINE RESERVOIR INFLOW          APR-JUL      12.8      19.5    |       24        80    |        29        35             30
                                                                    |                       |
HAMS FORK nr Frontier                APR-JUL        23        34    |       45        68    |        56        72             66
                                                                    |                       |
VIVA NAUGHTON RES inflow             APR-JUL        32        45    |       59        63    |        73        94             93
                                                                    |                       |
FLAMING GORGE RES INFLOW             APR-JUL       392       507    |      675        56    |       843      1090           1196
                                                                    |                       |
==================================================================================================================================
                         LOWER GREEN RIVER BASIN                        |                 LOWER GREEN RIVER BASIN
             Reservoir Storage (1000 AF) - End of December              |        Watershed Snowpack Analysis - January 1, 1998
==================================================================================================================================
                                      Usable |  *** Usable Storage ***  |                            Number     This Year as % of
Reservoir                            Capacity|  This      Last          |   Watershed                  of       =================
                                             |  Year      Year     Avg  |                          Data Sites   Last Yr   Average
========================================================================|=========================================================
FONTENELLE                             344.8    223.1    186.2    208.3 |   HAMS FORK RIVER             3        27        58
                                                                        |
FLAMING GORGE                                   NO REPORT               |   BLACKS FORK                 2        70        94
                                                                        |
VIVA NAUGHTON RES                               NO REPORT               |   HENRYS FORK                 2       124       192
                                                                        |
                                                                        |   GREEN above Flaming Gorge  18        31        63
                                                                        |
==================================================================================================================================
 * 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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