Upper North Platte River Basin (8)
March 2001

Snow
The snow courses above Seminoe Reservoir have about 80 percent of average snow water equivalent (SWE) recorded for this time of the year (89 percent of last year). SWE in the drainage area above Northgate is about 82 percent of average and 80 percent of last year at this time. SWE in the Encampment River drainage is about 76 percent of normal and 92 percent of last year. Brush Creek SWE for the year is about 86 percent of normal and 101 percent of last year's SWE. Medicine Bow and Rock Creek drainage SWE is about 72 percent of average and 101 percent of last year at this time. For more information see Basin Summary of Snow Courses at the beginning of this report.

Precipitation
Nine reporting stations indicate February precipitation was 96 percent of average and about 72 percent of last year's amount. February precipitation varied from 0 to 186 percent of average. Total water-year-to-date precipitation is about 80 percent of average for the basin, which is about 91 percent of last year's amount. Year to date percentage ranges from 44 to 103 percent of average for the 9 reporting stations.

Reservoirs
Seminoe Reservoir is currently storing about 159 percent of normal for this time of the year. The reservoir is storing 81 percent of last year's amount. Seminoe Reservoir is estimated to be storing 650,500 acre-feet (40 percent of capacity). Last year, at this time, the reservoir had 798,200 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 190,000 acre-feet (70 percent of average). Encampment River near Encampment is estimated to yield 125,000 acre-feet (80 percent of normal). Rock Creek near Arlington is estimated to yield 44,000 acre-feet (79 percent of average). Seminoe Reservoir inflow should be about (605,000 acre-feet (71 percent of normal). See the following table for more detailed information on projected runoff. 

  

==================================================================================================================================
                                                  UPPER NORTH PLATTE RIVER BASIN
                                               Streamflow Forecasts - March 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        74       143    |      190        70    |       237       306            271
                                                                    |                       |
Encampment River nr Encampment       APR-SEP        81       107    |      125        80    |       143       169            156
                                                                    |                       |
North Platte River nr Sinclair       APR-SEP       223       397    |      515        72    |       633       807            719
                                                                    |                       |
Rock Creek nr Arlington              APR-SEP        28        37    |       44        79    |        51        63             56
                                                                    |                       |
Medicine Bow River ab Seminoe Reserv APR-SEP        27        57    |       83        65    |       114       168            127
                                                                    |                       |
Seminoe Reservoir inflow             APR-JUL       265       444    |      565        72    |       686       865            788
                                     APR-SEP       292       478    |      605        71    |       732       918            851
                                                                    |                       |
==================================================================================================================================
                     UPPER NORTH PLATTE RIVER BASIN                     |             UPPER NORTH PLATTE RIVER BASIN
             Reservoir Storage (1000 AF) - End of February              |        Watershed Snowpack Analysis - March 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    650.5    798.2    409.0 |   N PLATTE above Northgate    7        80        82
                                                                        |
                                                                        |   ENCAMPMENT RIVER            4        92        76
                                                                        |
                                                                        |   BRUSH CREEK                 5       101        86
                                                                        |
                                                                        |   MEDICINE BOW & ROCK CREEK   3       101        72
                                                                        |
                                                                        |   N PLATTE above Seminoe     19        89        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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