Upper Green River Basin (11)
March 1998

Snow
The Upper Green River Basin snow water equivalent (SWE),above Fontenelle Reservoir, is 80 percent of average (53 percent of last year). SWE for the Green River above Warren Bridge is 76 percent of average and 49 percent of last year at this time. SWE on the west side of the Upper Green River basin is about 82 percent of normal, 55 percent of this time last year. Newfork River SWE is about 77 percent of normal - about 54 percent of last year at this time. SWE for Big Sandy - Eden Valley area is 67 percent of normal and 44 percent of last year. For more information see the Basin Summary of Snow Courses at the beginning of this report.

Precipitation
The 12 reporting precipitation sites in the basin were 45 percent of average for February; precipitation was 94 percent of last year at this time. February precipitation varied from 32 percent of normal (Kendall RS SNOTEL) to 167 percent above normal (Big Piney). Water year-to-date precipitation is about 31 percent below normal (56 percent of last year).

Reservoir
Big Sandy Reservoir is storing 23,900 acre feet (130 percent of average) and Eden is storing 3,500 acre feet (85 percent of average). Fontenelle Reservoir is about 78 percent of average (134,200 acre feet). Flaming Gorge reservoir contains about 3,247,000 acre feet this year compared to 3,150,600 acre feet last year. Detailed reservoir data is shown on the following page and on the reservoir storage summary at the beginning of this report.

Streamflow
The fifty percent chance April through July runoff, in the basin, is forecast below average. Green River at Warren Bridge is expected to yield about 230,000 acre feet (87 percent of normal). Pine Creek above Fremont Lake is expected to yield 95,000 acre feet ( 91 percent of normal). New Fork River near Big Piney is expected to yield about 325,000 acre feet (84 percent of normal). The 50 percent chance inflow to Fontenelle Reservoir is about 715,000 acre feet, which is about 84 percent of normal. Big Sandy near Farson is expected to be about 45,000 acre feet (79 percent of normal). 

==================================================================================================================================
                                                     UPPER 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 at Warren Bridge             APR-JUL       181       214    |      230        87    |       246       279            266
                                                                    |                       |
PINE CK abv Fremont Lake             APR-JUL        77        90    |       95        91    |       100       113            104
                                                                    |                       |
NEW FORK R nr Big Piney              APR-JUL       204       295    |      325        84    |       355       447            385
                                                                    |                       |
FONTENELLE RESERVOIR INFLOW          APR-JUL       501       639    |      715        84    |       791       934            849
                                                                    |                       |
BIG SANDY R nr Farson                APR-JUL        30        39    |       45        79    |        51        60             57
                                                                    |                       |
==================================================================================================================================
                         UPPER GREEN RIVER BASIN                        |                 UPPER 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
========================================================================|=========================================================
BIG SANDY                               38.3     23.9     16.2     18.4 |   GREEN above Warren Bridge   4        49        76
                                                                        |
EDEN                                    11.8      3.5      3.6      4.1 |   UPPER GREEN (West Side)     7        55        82
                                                                        |
FLAMING GORGE                         3749.0   3247.0   3150.6      --- |   NEWFORK RIVER               3        54        77
                                                                        |
FONTENELLE                             344.8    134.2    119.0    172.0 |   BIG SANDY/EDEN VALLEY       2        44        67
                                                                        |
                                                                        |   GREEN above Fontenelle     14        53        80
                                                                        |
==================================================================================================================================
 * 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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