Lower Green River Basin (12)
March 1998

Snow
The Blacks Fork drainage snow water equivalent (SWE) is 118 percent of average (93 % of last year). Henry's Fork is 118 percent of the March 1 average (93 % of last year). SWE in the Hams Fork, as of March 1, is 88 percent of average (59 % of last year). The basin as a whole is 89 percent of average (61 % of last year). For more information see Basin Summary of Snow Courses at beginning of this report.

Precipitation
Precipitation was well above average to well below throughout the basin during February. Precipitation ranged from 233 to 46 percent of average from the 4 reporting stations. The entire basin received 68 percent of average for the month (177 percent of last year). The basin year-to-date precipitation is currently 73 percent of average (54 % of last year).

Reservoir
Fontenelle Reservoir is currently storing 134,200 acre feet; this is 78 percent of average storage (13 % more than last year). Flaming Gorge is storing 3,247,000 acre feet (no average established). Viva Naughton is storing 23,400 acre feet (84 percent of average).

Streamflow
Water users can expect near 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 113 percent of average for State Line Reservoir inflow (34,000 acre feet) and 91 percent of average (60,000 acre feet) at Hams Fork near Frontier. Green River near Green River is forecast to yield 730,000 acre feet (81 percent of average). Meeks Cabin Reservoir inflow is estimated to flow 110,000 acre feet (115 percent of average). Viva Naughton Reservoir inflow will be about 80,000 acre feet (86 percent of average). Flaming Gorge Reservoir inflow should be near 1,050,000 acre feet (88 percent of average). 

==================================================================================================================================
                                                     LOWER GREEN RIVER BASIN
                                               Streamflow Forecasts - March 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       494       654    |      730        81    |       806       962            899
                                                                    |                       |
MEEKS CABIN RESERVOIR Inflow         APR-JUL        92       103    |      110       115    |       117       128             96
                                                                    |                       |
STATE LINE RESERVOIR INFLOW          APR-JUL        25        30    |       34       113    |        38        44             30
                                                                    |                       |
HAMS FORK nr Frontier                APR-JUL        38        51    |       60        91    |        69        83             66
                                                                    |                       |
VIVA NAUGHTON RES inflow             APR-JUL        50        68    |       80        86    |        92       110             93
                                                                    |                       |
FLAMING GORGE RES INFLOW             APR-JUL       646       925    |     1050        88    |      1175      1447           1196
                                                                    |                       |
==================================================================================================================================
                         LOWER GREEN RIVER BASIN                        |                 LOWER GREEN RIVER BASIN
             Reservoir Storage (1000 AF) - End of February              |        Watershed Snowpack Analysis - March 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    134.2    119.0    172.0 |   HAMS FORK RIVER             4        59        88
                                                                        |
FLAMING GORGE                         3749.0   3247.0   3150.6      --- |   BLACKS FORK                 5        93       118
                                                                        |
VIVA NAUGHTON RES                       42.4     23.4      ---     27.8 |   HENRYS FORK                 3       105       139
                                                                        |
                                                                        |   GREEN above Flaming Gorge  26        61        89
                                                                        |
==================================================================================================================================
 * 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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