Lower Green River Basin (12)
June 2001

Snow
The Lower Green River Basin is practically melted out as of June 1. Blacks Fork SWE is currently 4 percent of average. The Hams Fork and the Henry's fork are melted out. The basin, as a whole, is 1 percent of average. For more information see Basin Summary of Snow Courses at beginning of this report.

Precipitation
Precipitation was below average for the 3 reporting stations during May. Precipitation ranged from 20 to 40 percent of average for the month. The entire basin received 33 percent of average for the month (32 percent of last year). The basin year-to-date precipitation is currently 60 percent of average (83 percent of last year). Year to date percentages range from 58 to 84.

Reservoir
Usable storage in Fontenelle Reservoir this month is 117,200 acre feet (81 percent of average and 85 percent of last year). Viva Naughton is currently storing 42,900 acre feet (126 percent of average and 95 percent of last year). Flaming Gorge did not report this month.

Streamflow
Yield from the Lower Green River basin is forecast much below average. Irrigators without a storage facility may experience water shortage. Expected yields vary from 3 to 66 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 335,000-acre feet (37 percent of average). Blacks Fork near Robertson is forecast to yield 63,000-acre feet (66 percent of average). East Fork of Smiths Fork near Robertson is estimated to yield 19,000 acre-feet (63 percent of average). The estimated yield for Hams Fork near Frontier is 26,000-acre feet (39 percent of average). Viva Naughton Reservoir inflow will be about 30,000-acre feet (34 percent of average). Flaming Gorge Reservoir inflow will be about 500,000-acre feet (42 percent of average). 

==================================================================================================================================
                                                     LOWER GREEN RIVER BASIN
                                               Streamflow Forecasts - June 1, 2001
==================================================================================================================================
                                              |  <<====== 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       192       279    |      335        37    |       391       497            899
                                                                    |                       |
Blacks Fork nr Robertson             APR-JUL        52        58    |       63        66    |        68        75             95
                                                                    |                       |
EF of Smiths Fork nr Robertson       APR-JUL      17.1      18.1    |     19.0        63    |        20        22             30
                                                                    |                       |
Hams Fk blw Pole Ck nr Frontier      APR-JUL      17.6        22    |       26        39    |        30        36             66
                                                                    |                       |
Hams Fk Inflow to Viva Naughton Res  APR-JUL      10.8        22    |       30        34    |        38        49             89
                                                                    |                       |
Flaming Gorge Reservoir Inflow       APR-JUL       310       423    |      500        42    |       577       690           1196
                                                                    |                       |
==================================================================================================================================
                         LOWER GREEN RIVER BASIN                        |                 LOWER GREEN RIVER BASIN
             Reservoir Storage (1000 AF) - End of May                   |        Watershed Snowpack Analysis - June 1, 2001
==================================================================================================================================
                                      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    158.5    187.1    195.5 |   HAMS FORK RIVER             3         0         0
                                                                        |
FLAMING GORGE                                   NO REPORT               |   BLACKS FORK                 2         0         4
                                                                        |
VIVA NAUGHTON RES                       42.4     42.9     45.2     34.0 |   HENRYS FORK                 2         0         0
                                                                        |
                                                                        |   GREEN above Flaming Gorge  18         6         1
                                                                        |
==================================================================================================================================
 * 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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