Powder and Tongue River Basins (6)
February 2000

Snow
The Upper Tongue River drainage is 93 percent of normal (103 percent of last year). Goose Creek drainage is 81 percent of average (103 percent of last year). Clear Creek drainage is 88 percent of normal (96 percent of last year). Crazy Woman Drainage is 73 percent of normal (84 percent of last year). The Upper Powder River is 73 percent of normal (89 percent of last year). The Powder River basin snow water equivalent (SWE), in Wyoming, is about 80 percent of average (92 percent of last year). For more information see Basin Summary of Snow Courses at beginning of report.

Precipitation
January precipitation was 122 percent of average for the 11 reporting stations (79 percent of last year). Monthly percentages range from 50 to 441 percent of average. Precipitation for the year ranges from 36 to 163 percent of average. Year-to-date precipitation is about 93 percent of average in the basin; this is 69 percent of last year at this time.

Reservoir
Tongue River Reservoir is currently at 135 percent of average storage for this time of year (that is 36,600 acre feet). The total reservoir capacity is about 68,000 acre feet. 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 100,000 acre-feet (87 percent of normal). Water users on the Middle Fork near Barnum should have a yield near 9,900 acre-feet (50 percent of normal). The North Fork of the Powder near Hazelton should yield about 6,900 acre-feet (68 percent of normal). The estimated yield for Clear Creek near Buffalo is 29,000 acre-feet (74 percent of average). Rock Creek near Buffalo will yield about 19,200 acre-feet (80 percent of normal), and Piney Creek at Kearny should yield about 42,000 acre-feet (82 percent of average). 

==================================================================================================================================
                                                   POWDER & TONGUE RIVER BASINS
                                               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)
====================================================================|=======================|=====================================
TONGUE RIVER nr Dayton (2)           APR-SEP        70        88    |      100        87    |       112       130            115
                                                                    |                       |
MIDDLE FORK POWDER nr Barnum         APR-SEP       2.3       6.8    |      9.9        50    |      13.0      17.5           19.7
                                                                    |                       |
NORTH FORK POWDER nr Hazelton        APR-SEP       4.3       5.8    |      6.9        68    |       8.0       9.5           10.1
                                                                    |                       |
CLEAR CREEK nr Buffalo               APR-SEP        21        26    |       29        74    |        32        37             39
                                                                    |                       |
ROCK CREEK nr Buffalo                APR-SEP      13.9      17.1    |     19.2        80    |        21        25             24
                                                                    |                       |
PINEY CREEK at Kearny                APR-SEP      15.6        31    |       42        82    |        53        68             51
                                                                    |                       |
==================================================================================================================================
                      POWDER & TONGUE RIVER BASINS                      |              POWDER & TONGUE RIVER BASINS
             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
========================================================================|=========================================================
TONGUE RIVER                            68.0     36.6      6.2     27.1 |   UPPER TONGUE RIVER          9       103        93
                                                                        |
                                                                        |   GOOSE CREEK                 3       103        81
                                                                        |
                                                                        |   CLEAR CREEK                 4        96        88
                                                                        |
                                                                        |   CRAZY WOMAN CREEK           3        84        73
                                                                        |
                                                                        |   UPPER POWDER RIVER          4        89        73
                                                                        |
                                                                        |   POWDER RIVER in WY          8        92        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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