Powder and Tongue River Basins (6)
February 2002

Snow
Snow water equivalent (SWE) in the Upper Tongue River drainage is 72 percent of normal (111 percent of last year). The Goose Creek drainage is 71 percent of average (104 percent of last year). Clear Creek drainage is 73 percent of normal SWE (126 percent of last year). Crazy Woman Creek is 76 percent of average (168 percent of last year). The Upper Powder River drainage is 72 percent of average (121 percent of last year). The Powder River basin snow water equivalent (SWE), in Wyoming, is about 73 percent of average (123 percent of last year). For more information see Basin Summary of Snow Courses at beginning of report.

Precipitation
January precipitation was 71 percent of average for the 11 reporting stations. Monthly percentages range from 9 to 132 percent of average. Precipitation for the year ranges from 59 to 113 percent of average at the reporting stations. Year-to-date precipitation is about 84 percent of average in the basin; this is 123 percent of last year at this time.

Reservoir
Tongue River Reservoir is currently at 96 percent of average storage for this time of year (21,800 acre feet) – the reservoir is about 28 percent of capacity (total capacity is 79,100 acre feet). Last year at this time the reservoir was storing about 34,000 acre feet – average storage is about 22,700 acre feet for this time of the year. Detailed reservoir data is shown on the following page and on the reservoir storage summary at the beginning of this report.

Streamflow
The following runoff values are for the 50 percent probability during the April through September forecast period. The estimated yield for Tongue River near Dayton is 59,000-acre feet (54 percent of normal). Middle Fork of the Powder River near Barnum is estimated to yield 8,700-acre feet (47 percent of average). The North Fork of the Powder near Hazelton should yield about 5,700 acre-feet (55 percent of normal). The estimated yield for Clear Creek near Buffalo is 21,000 acre-feet (54 percent of average). Rock Creek near Buffalo will yield about 12,500 acre-feet (52 percent of normal), and Piney Creek at Kearny should yield about 25,000 acre-feet (48 percent of average). 

==================================================================================================================================
                                                   POWDER & TONGUE RIVER BASINS
                                               Streamflow Forecasts - February 1, 2002
==================================================================================================================================
                                              |  <<====== 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 nr Dayton (2)           APR-SEP        43        52    |       59        54    |        71        89            109
                                                                    |                       |
MIDDLE FORK POWDER nr Barnum         APR-SEP       5.1       7.2    |      8.7        47    |      11.8      16.3           18.7
                                                                    |                       |
NORTH FORK POWDER nr Hazelton        APR-SEP       4.2       5.1    |      5.7        55    |       6.8       8.3           10.4
                                                                    |                       |
CLEAR CREEK nr Buffalo               APR-SEP      16.7      19.3    |       21        54    |        24        29             39
                                                                    |                       |
ROCK CREEK nr Buffalo                APR-SEP       9.8      11.4    |     12.5        52    |      14.6      17.8             24
                                                                    |                       |
PINEY CREEK at Kearny                APR-SEP      12.3      19.9    |       25        48    |        36        51             52
                                                                    |                       |
==================================================================================================================================
                      POWDER & TONGUE RIVER BASINS                      |              POWDER & TONGUE RIVER BASINS
             Reservoir Storage (1000 AF) - End of January               |        Watershed Snowpack Analysis - February 1, 2002
==================================================================================================================================
                                      Usable |  *** Usable Storage ***  |                            Number     This Year as % of
Reservoir                            Capacity|  This      Last          |   Watershed                  of       =================
                                             |  Year      Year     Avg  |                          Data Sites   Last Yr   Average
========================================================================|=========================================================
TONGUE RIVER                            79.1     21.8     34.0     22.7 |   UPPER TONGUE RIVER          9       111        72
                                                                        |
                                                                        |   GOOSE CREEK                 2       108        71
                                                                        |
                                                                        |   CLEAR CREEK                 4       126        73
                                                                        |
                                                                        |   CRAZY WOMAN CREEK           3       168        76
                                                                        |
                                                                        |   UPPER POWDER RIVER          4       121        72
                                                                        |
                                                                        |   POWDER RIVER in WY          8       123        73
                                                                        |
==================================================================================================================================
 * 90%, 70%, 30%, and 10% chances of exceeding are the probabilities that the actual volume will exceed the volumes in the table.

(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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