Powder and Tongue River Basins
March 1997

Snow
The basin is in good shape as far as snowpack is concerned. All drainage's within the Powder and Tongue River basin are above average. The entire basin, in Wyoming, is now 128 percent of average Snow Water Equivalent (SWE). The upper Tongue River drainage is about 14 percent above normal; the Goose Creek drainage is about 6 percent ahead of normal; the Clear Creek drainage is 29 percent above normal; the Crazy Woman Drainage is 31 percent above normal. The Upper Powder is 27 percent above normal. For more information see Basin Summary of Snow Courses at beginning of report.

Precipitation
Year-to-date precipitation is 20 percent above average in the basin; this is 18 percent better than it was last year at this time. February precipitation was 14 percent above average (44 percent more than last year). February precipitation for Powder River Pass was 189 percent of average.

Reservoir
Storage in the Tongue River Reservoir this month is 23,100 acre feet (77 percent of average).

Streamflow
The following values are for the 50 percent probability during the April to September forecast period. the Tongue River near Dayton is estimated to yield 130,000 acre feet (13 percent above normal). Water users on the Middle Fork near Barnum should have a yield near 24,100 acre feet (22 percent above normal). The North Fork near Hazelton should yield about 11,500 acre feet (14 percent above normal). Clear Creek near Buffalo is estimated to yield 52,000 acre feet (33 percent above average). Rock Creek near Buffalo will yield about 26,400 acre feet (10 percent above normal) and Piney Creek at Kearny should yield about 62,000 acre feet (122 percent above average). 

==================================================================================================================================
                                                   POWDER & TONGUE RIVER BASINS
                                               Streamflow Forecasts - March 1, 1997
==================================================================================================================================
                                              |  <<====== 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)
====================================================================|=======================|=====================================
TONGUE RIVER near Dayton (2)         APR-SEP       100       118    |      130       113    |       142       160            115
                                                                    |                       |
MIDDLE FORK POWDER near Barnum       APR-SEP      17.2        21    |       24       122    |        27        31           19.7
                                                                    |                       |
NORTH FORK POWDER near Hazelton      APR-SEP       8.1      10.1    |     11.5       114    |      12.9      14.9           10.1
                                                                    |                       |
CLEAR CREEK near Buffalo             APR-SEP        44        49    |       52       133    |        55        60             39
                                                                    |                       |
ROCK CREEK near Buffalo              APR-SEP        21        24    |       26       110    |        29        32             24
                                                                    |                       |
PINEY CREEK at Kearny                APR-SEP        39        53    |       62       122    |        71        85             51
                                                                    |                       |
==================================================================================================================================
                      POWDER & TONGUE RIVER BASINS                      |              POWDER & TONGUE RIVER BASINS
             Reservoir Storage (1000 AF) - End of February              |        Watershed Snowpack Analysis - March 1, 1997
==================================================================================================================================
                                      Usable |  *** Usable Storage ***  |                            Number     This Year as % of
Reservoir                            Capacity|  This      Last          |   Watershed                  of       =================
                                             |  Year      Year     Avg  |                          Data Sites   Last Yr   Average
========================================================================|=========================================================
TONGUE RIVER                            68.0     23.1     34.2     30.1 |   UPPER TONGUE RIVER          9       112       114
                                                                        |
                                                                        |   GOOSE CREEK                 3       111       106
                                                                        |
                                                                        |   CLEAR CREEK                 4       115       129
                                                                        |
                                                                        |   CRAZY WOMAN CREEK           3       123       131
                                                                        |
                                                                        |   UPPER POWDER RIVER          5       148       127
                                                                        |
                                                                        |   POWDER RIVER in WY          9       133       128
                                                                        |
==================================================================================================================================
 * 90%, 70%, 30%, and 10% chances of exceeding are the probabilities that the actual flow 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 flow - actual flow may be affected by upstream water management.
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