Lower Green River Basin (12)
March 1999

Snow
The Blacks Fork drainage snow water equivalent (SWE) is 116 percent of average (99 % of last year). SWE in the Hams Fork, as of March 1, is 110 percent of average (126% of last year). Henry's Fork is 110 percent of average (79 percent of last year). The basin, as a whole, is 113 percent of average (126 % of last year). For more information see Basin Summary of Snow Courses at beginning of this report.

Precipitation
Precipitation was above average for the 4 reporting stations during February. Precipitation ranged from 127 to 171 percent of average for the month. The entire basin received 159 percent of average for the month (222 percent of last year). The basin year-to-date precipitation is currently 93 percent of average (123 percent of last year). Year to date percentages range from 81 to 95.

Reservoir
Fontenelle Reservoir is currently storing 144,800 acre feet; this is 84 percent of average (108 % of last year). Flaming Gorge is currently storing 3,265,000 acre feet (at this time last year the reservoir was storing 3,247,000 acre feet). Flaming Gorge has a maximum capacity of 3,749,000 acre feet. Viva Naughton is currently storing 30,600 acre feet (110 percent of average).

Streamflow
Expected yields vary from 105 to 113 percent of average across the basin. The following forecast values are based on a 50 percent chance probability for the April through July forecast period. Green River near Green River is forecast to yield about 985,000-acre feet (110 percent of average). East Fork of Smiths Fork near Robertson is estimated to yield 34,000 acre-feet (113 percent of average). The estimated yield for Hams Fork near Frontier is 70,000-acre feet (106 percent of average). Viva Naughton Reservoir inflow will be about 93,000-acre feet (105 percent of average). 

==================================================================================================================================
                                                     LOWER GREEN RIVER BASIN
                                               Streamflow Forecasts - March 1, 1999
==================================================================================================================================
                                              |  <<====== 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 River nr Green River, WY       APR-JUL       746       890    |      985       110    |      1080      1223            899
                                                                    |                       |
Blacks Fork nr Robertson             APR-JUL        77        94    |      105       111    |       116       133             95
                                                                    |                       |
EF of Smiths Fork nr Robertson       APR-JUL        26        30    |       34       113    |        38        45             30
                                                                    |                       |
Hams Fk blw Pole Ck nr Frontier      APR-JUL        48        61    |       70       106    |        80        92             66
                                                                    |                       |
Hams Fk Inflow to Viva Naughton Res  APR-JUL        61        80    |       93       105    |       106       125             89
                                                                    |                       |
Flaming Gorge Reservoir Inflow       APR-JUL       945      1218    |     1350       113    |      1483      1746           1196
                                                                    |                       |
==================================================================================================================================
                         LOWER GREEN RIVER BASIN                        |                 LOWER GREEN RIVER BASIN
             Reservoir Storage (1000 AF) - End of February              |        Watershed Snowpack Analysis - March 1, 1999
==================================================================================================================================
                                      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    144.8    134.2    172.0 |   HAMS FORK RIVER             4       126       110
                                                                        |
FLAMING GORGE                         3749.0   3265.3   3247.0      --- |   BLACKS FORK                 5        99       116
                                                                        |
VIVA NAUGHTON RES                       42.4     30.6     23.4     27.8 |   HENRYS FORK                 3        79       110
                                                                        |
                                                                        |   GREEN above Flaming Gorge  26       126       113
                                                                        |
==================================================================================================================================
 * 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.
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