Lower Green River Basin
January 1997

Snow
The Blacks Fork drainage snow water equivalent (SWE) is 133 percent of average, currently the lowest in the basin. Henrys Fork is about 155 percent of average. Snowpack in the Hams Fork, as of January 1, is 217 percent of average. The basin as a whole is 204 percent of average. For more information see Basin Summary of Snow Courses at beginning of this report.

Precipitation
Precipitation was very heavy throughout the basin during December. Precipitation ranged from 166 percent of average at Rock Springs to 336 percent of average at Kemmerer. The entire basin received 244 percent of average for the month (195 percent of last year). The basin year to date precipitation is currently 165 percent of average; sites range from 135 to 199 percent of average.

Reservoir
Fontenelle Reservoir is currently storing 186,200 acre feet; this is 89 percent of average storage. Flaming Gorge currently is storing 3,249,000 acre feet; although an average is not established, that is 87 percent of the total capacity. Viva Naughton did not report.

Streamflow
Water users can expect above average yields in the basin this season. The following forecast values are based on a 50 percent chance probability for the April to September forecast period. Yields will range from 120 percent of average for Meeks Cabin Reservoir inflow (115,000 acre feet) to 182 percent of average (120,000 acre feet) at Hams Fork near Frontier. Green River near Green River is forecast to yield 1,300,000 acre feet (145 percent of average). State Line Reservoir inflow is estimated to flow 127 percent of average (38,000 acre feet). Viva Naughton Reservoir inflow will be about 165,000 acre feet (177 percent of average). Flaming Gorge Reservoir inflow should be near 1,800,000 acre feet (151 percent of average. 

==================================================================================================================================
                                                     LOWER GREEN RIVER BASIN
                                               Streamflow Forecasts - January 1, 1997
==================================================================================================================================
                                              |  <<====== 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       818      1184    |     1300       145    |      1416      1780            899
                                                                    |                       |
MEEKS CABIN RESERVOIR Inflow         APR-JUL        87       104    |      115       120    |       126       143             96
                                                                    |                       |
STATE LINE RESERVOIR INFLOW          APR-JUL        27        34    |       38       127    |        43        49             30
                                                                    |                       |
HAMS FORK nr Frontier                APR-JUL        93       109    |      120       182    |       131       147             66
                                                                    |                       |
VIVA NAUGHTON RES inflow             APR-JUL       130       151    |      165       177    |       179       200             93
                                                                    |                       |
FLAMING GORGE RES INFLOW             APR-JUL      1112      1632    |     1800       151    |      1968      2488           1196
                                                                    |                       |
==================================================================================================================================
                         LOWER GREEN RIVER BASIN                        |                 LOWER GREEN RIVER BASIN
             Reservoir Storage (1000 AF) - End of December              |        Watershed Snowpack Analysis - January 1, 1997
==================================================================================================================================
                                      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    186.2    216.0    208.3 |   HAMS FORK RIVER             3       149       217
                                                                        |
FLAMING GORGE                         3749.0   3249.0   3279.0      --- |   BLACKS FORK                 2       130       133
                                                                        |
VIVA NAUGHTON RES                               NO REPORT               |   HENRYS FORK                 2       271       155
                                                                        |
                                                                        |   GREEN above Flaming Gorge  17       149       204
                                                                        |
==================================================================================================================================
 * 90%, 70%, 30%, and 10% chances of exceeding are the probabilities that the actual flow 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 flow - actual flow may be affected by upstream water management.
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