Upper North Platte River Basin (8)
January 2001

Snow
The snow courses above Seminoe Reservoir have about 88 percent of average snow water equivalent (SWE) recorded for this time of the year (136 percent of last year). SWE in the drainage area above Northgate is about 94 percent of average and 137 percent of last year at this time. SWE in the Encampment River drainage is about 79 percent of normal and 146 percent of last year. Brush Creek SWE for the year is about 110 percent of normal and 114 percent of last year's SWE. Medicine Bow and Rock Creek drainage SWE is about 83 percent of average and 156 percent of last year at this time. For more information see Basin Summary of Snow Courses at the beginning of this report.

Precipitation
Eight reporting stations indicate December precipitation was 96 percent of average and about 108 percent of last year's amount. December precipitation varied from 34 to 173 percent of average. Total water-year-to-date precipitation is about 81 percent of average for the basin, which is about 149 percent of last year's amount. Year to date percentage ranges from 86 to 152 percent of average for the 8 reporting stations.

Reservoirs
Seminoe Reservoir is currently storing about 132 percent of normal for this time of the year. Currently, the reservoir is storing 85 percent of last year's amount. Seminoe Reservoir is estimated to be storing 717,900 acre- feet (71 percent of capacity). Last year, at this time, the reservoir had 845,600 acre-feet in storage.

Streamflow
All the following yields are based on the fifty percent chance April through September yield. Yield for the North Platte River near Northgate is expected to be about 245,000 acre-feet (90 percent of average). Encampment River near Encampment is estimated to yield 130,000 acre-feet (83 percent of normal). Rock Creek near Arlington is estimated to yield 53,000 acre-feet (95 percent of average). Seminoe Reservoir inflow should be about (760,000 acre-feet (89 percent of normal). See the following table for more detailed information on projected runoff. 

  
==================================================================================================================================
                                                  UPPER NORTH PLATTE RIVER BASIN
                                               Streamflow Forecasts - January 1, 2001
==================================================================================================================================
                                              |  <<====== 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)
====================================================================|=======================|=====================================
North Platte River nr Northgate      APR-SEP        99       186    |      245        90    |       304       391            271
                                                                    |                       |
Encampment River nr Encampment       APR-SEP        58       101    |      130        83    |       159       202            156
                                                                    |                       |
Rock Creek nr Arlington              APR-SEP        33        44    |       53        95    |        63        78             56
                                                                    |                       |
Seminoe Reservoir inflow             APR-JUL       297       543    |      710        90    |       877      1123            788
                                     APR-SEP       384       608    |      760        89    |       912      1136            851
                                                                    |                       |
==================================================================================================================================
                     UPPER NORTH PLATTE RIVER BASIN                     |             UPPER NORTH PLATTE RIVER BASIN
             Reservoir Storage (1000 AF) - End of December              |        Watershed Snowpack Analysis - January 1, 2001
==================================================================================================================================
                                      Usable |  *** Usable Storage ***  |                            Number     This Year as % of
Reservoir                            Capacity|  This      Last          |   Watershed                  of       =================
                                             |  Year      Year     Avg  |                          Data Sites   Last Yr   Average
========================================================================|=========================================================
SEMINOE                               1016.7    717.9    845.6    542.0 |   N PLATTE above Northgate    5       137        94
                                                                        |
                                                                        |   ENCAMPMENT RIVER            3       146        79
                                                                        |
                                                                        |   BRUSH CREEK                 2       114       110
                                                                        |
                                                                        |   MEDICINE BOW & ROCK CREEK   2       156        83
                                                                        |
                                                                        |   N PLATTE above Seminoe     13       136        88
                                                                        |
==================================================================================================================================
 * 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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