Powder and Tongue River Basins (6)
March 2000

Snow
Snow water equivalent (SWE) in the Upper Tongue River drainage is 93 percent of normal (102 percent of last year). Goose Creek drainage SWE is 85 percent of average (99 percent of last year). Clear Creek drainage is 92 percent of normal SWE (109 percent of last year). Crazy Woman Drainage is 78 percent of normal (82 percent of last year). The Upper Powder River is 82 percent of normal (86 percent of last year). The Powder River basin snow water equivalent (SWE), in Wyoming, is about 87 percent of average (96 percent of last year). For more information see Basin Summary of Snow Courses at beginning of report.

Precipitation
February precipitation was 114 percent of average for the 10 reporting stations (100 percent of last year). Monthly percentages range from 80 to 160 percent of average. Precipitation for the year ranges from 68 to 110 percent of average. Year-to-date precipitation is about 95 percent of average in the basin; this is 81 percent of last year at this time.

Reservoir
Tongue River Reservoir is currently at 122 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 105,000 acre-feet (91 percent of normal). Water users on the Middle Fork near Barnum should have a yield near 9,000 acre-feet (46 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 29,500 acre-feet (76 percent of average). Rock Creek near Buffalo will yield about 20,000 acre-feet (83 percent of normal), and Piney Creek at Kearny should yield about 43,000 acre-feet (84 percent of average). 

==================================================================================================================================
                                                   POWDER & TONGUE RIVER BASINS
                                               Streamflow Forecasts - March 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        76        93    |      105        91    |       117       134            115
                                                                    |                       |
MIDDLE FORK POWDER nr Barnum         APR-SEP       1.8       6.1    |      9.0        46    |      11.9      16.2           19.7
                                                                    |                       |
NORTH FORK POWDER nr Hazelton        APR-SEP       4.3       5.9    |      6.9        68    |       7.9       9.5           10.1
                                                                    |                       |
CLEAR CREEK nr Buffalo               APR-SEP      17.8        25    |       30        76    |        34        41             39
                                                                    |                       |
ROCK CREEK nr Buffalo                APR-SEP      14.4      17.7    |       20        83    |        22        26             24
                                                                    |                       |
PINEY CREEK at Kearny                APR-SEP      16.2        32    |       43        84    |        54        70             51
                                                                    |                       |
==================================================================================================================================
                      POWDER & TONGUE RIVER BASINS                      |              POWDER & TONGUE RIVER BASINS
             Reservoir Storage (1000 AF) - End of February              |        Watershed Snowpack Analysis - March 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      7.8     30.1 |   UPPER TONGUE RIVER          8       106        93
                                                                        |
                                                                        |   GOOSE CREEK                 2       105        85
                                                                        |
                                                                        |   CLEAR CREEK                 4       109        92
                                                                        |
                                                                        |   CRAZY WOMAN CREEK           3        82        78
                                                                        |
                                                                        |   UPPER POWDER RIVER          4        86        82
                                                                        |
                                                                        |   POWDER RIVER in WY          8        96        87
                                                                        |
==================================================================================================================================
 * 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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