Lower Green River Basin (12)
January 2000

Snow
The Blacks Fork drainage snow water equivalent (SWE) is 65 percent of average (89 % of last year). SWE in the Hams Fork, as of January 1, is 51 percent of average (58% of last year). The Henry's Fork SWE for the basin 86 percent of average (81 % of last year). The basin, as a whole, is 59 percent of average (62 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 December. Precipitation ranged from 42 to 111 percent of average for the month. The entire basin received 53 percent of average for the month (72 percent of last year). The basin year-to-date precipitation is currently 39 percent of average (52 percent of last year). Year to date percentages range from 30 to 44.

Reservoir
Fontenelle Reservoir is currently storing 210,400 acre feet; this is 101 percent of average (93 % of last year). Flaming Gorge did not report this month. Viva Naughton did not report this month.

Streamflow
Expected yields vary from 48 to 67 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 530,000-acre feet (59 percent of average). East Fork of Smiths Fork near Robertson is estimated to yield 19,400 acre-feet (65 percent of average). The estimated yield for Hams Fork near Frontier is 35,000-acre feet (53 percent of average). Viva Naughton Reservoir inflow will be about 43,000-acre feet (48 percent of average). 

==================================================================================================================================
                                                     LOWER GREEN RIVER BASIN
                                               Streamflow Forecasts - January 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       243       405    |      530        59    |       655      1007            899
                                                                    |                       |
Blacks Fork nr Robertson             APR-JUL        33        51    |       64        67    |        77        95             95
                                                                    |                       |
EF of Smiths Fork nr Robertson       APR-JUL      14.4      17.2    |     19.4        65    |        22        26             30
                                                                    |                       |
Hams Fk blw Pole Ck nr Frontier      APR-JUL      18.0        27    |       35        53    |        44        58             66
                                                                    |                       |
Hams Fk Inflow to Viva Naughton Res  APR-JUL      16.9        26    |       43        48    |        60        86             89
                                                                    |                       |
Flaming Gorge Reservoir Inflow       APR-JUL       251       553    |      725        61    |       897      1423           1196
                                                                    |                       |
==================================================================================================================================
                         LOWER GREEN RIVER BASIN                        |                 LOWER GREEN RIVER BASIN
             Reservoir Storage (1000 AF) - End of December              |        Watershed Snowpack Analysis - January 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    210.4    226.9    208.3 |   HAMS FORK RIVER             3        58        51
                                                                        |
FLAMING GORGE                         3749.0   3269.0   3401.0      --- |   BLACKS FORK                 2        89        65
                                                                        |
VIVA NAUGHTON RES                               NO REPORT               |   HENRYS FORK                 2        81        86
                                                                        |
                                                                        |   GREEN above Flaming Gorge  18        63        59
                                                                        |
==================================================================================================================================
 * 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.
(3) - Forecasts produced in cooperation with Alberta Forecasting Staff Canada
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