Lower Green River Basin (12)
February 1998

Snow
The Blacks Fork drainage snow water equivalent (SWE) is 109 percent of average (78 % of last year). Henry's Fork is 163 percent of the February 1 average (97 % of last year). SWE in the Hams Fork, as of February 1, is 95 percent of average (52 % of last year). The basin as a whole is 91 percent of average (52 % of last year). For more information see Basin Summary of Snow Courses at beginning of this report.

Precipitation
Precipitation was above average throughout the basin during January. Precipitation ranged from 109 to 148 percent of average from the 4 reporting stations. The entire basin received 130 percent of average for the month (90 percent of last year). The basin year-to-date precipitation is currently 75 percent of average (47 % of last year).

Reservoir
Fontenelle Reservoir is currently storing 176,100 acre feet; this is 90 percent of average storage (18 % more than last year). Flaming Gorge is storing 3,279,000 acre feet (no average established). Viva Naughton is storing 25,000 acre feet (87 percent of average).

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 83 percent of average (55,000 acre feet) at Hams Fork near Frontier. Green River near Green River is forecast to yield 700,000 acre feet (78 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 73,000 acre feet (79 percent of average). Flaming Gorge Reservoir inflow should be near 950,000 acre feet (79 percent of average). 

==================================================================================================================================
                                                     LOWER 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 nr Green River, WY           APR-JUL       414       607    |      700        78    |       793       989            899
                                                                    |                       |
MEEKS CABIN RESERVOIR Inflow         APR-JUL        54        69    |       80        83    |        91       106             96
                                                                    |                       |
STATE LINE RESERVOIR INFLOW          APR-JUL      13.7      19.8    |       24        80    |        28        34             30
                                                                    |                       |
HAMS FORK nr Frontier                APR-JUL        30        45    |       55        83    |        65        80             66
                                                                    |                       |
VIVA NAUGHTON RES inflow             APR-JUL        39        59    |       73        79    |        87       107             93
                                                                    |                       |
FLAMING GORGE RES INFLOW             APR-JUL       502       805    |      950        79    |      1095      1399           1196
                                                                    |                       |
==================================================================================================================================
                         LOWER GREEN RIVER BASIN                        |                 LOWER 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
========================================================================|=========================================================
FONTENELLE                             344.8    176.1    149.6    196.2 |   HAMS FORK RIVER             4        52        95
                                                                        |
VIVA NAUGHTON RES                       42.4     25.0     27.1     28.7 |   BLACKS FORK                 0         0         0
                                                                        |
                                                                        |   HENRYS FORK                 0         0         0
                                                                        |
                                                                        |   GREEN above Flaming Gorge  18        49        87
                                                                        |
==================================================================================================================================
 * 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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