Lower Green River Basin (12)
February 2000

Snow
The Blacks Fork drainage snow water equivalent (SWE) is 92 percent of average (102 % of last year). SWE in the Hams Fork, as of February 1, is 76 percent of average (85% of last year). The Henry's Fork SWE for the basin 100 percent of average (82 % of last year). The basin, as a whole, is 81 percent of average (86 percent of last year). For more information see Basin Summary of Snow Courses at beginning of this report.

Precipitation
Precipitation was above average for the 3 reporting stations during January. Precipitation ranged from 6 to 99 percent of average for the month. The entire basin received 96 percent of average for the month (115 percent of last year). The basin year-to-date precipitation is currently 56 percent of average (73 percent of last year). Year to date percentages range from 50 to 60.

Reservoir
Fontenelle Reservoir is currently storing 167,600 acre feet; this is 85 percent of average (93 % of last year). Flaming Gorge does not have an average established. Viva Naughton is currently storing 35,700 acre feet; this is 124 percent of average (114 % of last year).

Streamflow
Expected yields vary from 62 to 80 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 665,000-acre feet (74 percent of average). East Fork of Smiths Fork near Robertson is estimated to yield 23,000 acre-feet (77 percent of average). The estimated yield for Hams Fork near Frontier is 45,000-acre feet (68 percent of average). Viva Naughton Reservoir inflow will be about 55,000-acre feet (62 percent of average). 

==================================================================================================================================
                                                     LOWER GREEN RIVER BASIN
                                               Streamflow Forecasts - February 1, 2000
==================================================================================================================================
                                              |  <<====== 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       378       559    |      665        74    |       771       953            899
                                                                    |                       |
Blacks Fork nr Robertson             APR-JUL        46        64    |       76        80    |        88       106             95
                                                                    |                       |
EF of Smiths Fork nr Robertson       APR-JUL      17.2        20    |       23        77    |        26        31             30
                                                                    |                       |
Hams Fk blw Pole Ck nr Frontier      APR-JUL        25        36    |       45        68    |        55        70             66
                                                                    |                       |
Hams Fk Inflow to Viva Naughton Res  APR-JUL      17.6        40    |       55        62    |        70        92             89
                                                                    |                       |
Flaming Gorge Reservoir Inflow       APR-JUL       454       752    |      900        75    |      1048      1351           1196
                                                                    |                       |
==================================================================================================================================
                         LOWER GREEN RIVER BASIN                        |                 LOWER GREEN RIVER BASIN
             Reservoir Storage (1000 AF) - End of January               |        Watershed Snowpack Analysis - February 1, 2000
==================================================================================================================================
                                      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    167.6    180.9    196.2 |   HAMS FORK RIVER             4        85        76
                                                                        |
FLAMING GORGE                         3749.0   3226.0   3341.0      --- |   BLACKS FORK                 2       102        92
                                                                        |
VIVA NAUGHTON RES                       42.4     35.7     31.4     28.7 |   HENRYS FORK                 2        82       100
                                                                        |
                                                                        |   GREEN above Flaming Gorge  22        86        81
                                                                        |
==================================================================================================================================
 * 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.
To February 2000 Basin Outlook Report Contents Page