Upper North Platte River Basin (8)
February 2002

Snow
The snow courses above Seminoe Reservoir have about 60 percent of average snow water equivalent (SWE) recorded for this time of the year (79 percent of last year). SWE in the drainage area above Northgate is about 59 percent of average and 76 percent of last year at this time. SWE in the Encampment River drainage is about 64 percent of normal and 88 percent of last year. Brush Creek SWE for the year is about 66 percent of normal and 79 percent of last year's SWE. Medicine Bow and Rock Creek drainage SWE is about 47 percent of average and 67 percent of last year at this time. For more information see Basin Summary of Snow Courses at the beginning of this report.

Precipitation
Eleven reporting stations indicate last month's precipitation was 52 percent of average and about 117 percent of last year's amount. Precipitation varied from 7 to 106 percent of average. Total water-year-to-date precipitation is about 67 percent of average for the basin, which is about 92 percent of last year's amount. Year to date percentage ranges from 57 to 93 percent of average for the 11 reporting stations.

Reservoirs
Seminoe Reservoir is currently storing about 84 percent of normal for this time of the year. Currently, the reservoir is storing 67 percent of last year's amount. Seminoe Reservoir is estimated to be storing 480,000 acre-feet (47 percent of capacity). Last year, at this time, the reservoir had 680,900 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 120,000 acre-feet (44 percent of average). Encampment River near Encampment is estimated to yield 110,000 acre-feet (67 percent of normal). Rock Creek near Arlington is estimated to yield 32,000 acre-feet (56 percent of average). Seminoe Reservoir inflow should be about (420,000 acre-feet (49 percent of normal). See the following table for more detailed information on projected runoff. 

==================================================================================================================================
                                                  UPPER NORTH PLATTE RIVER BASIN
                                               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)
====================================================================|=======================|=====================================
North Platte River nr Northgate      APR-SEP        71       100    |      120        44    |       165       232            270
                                                                    |                       |
Encampment River nr Encampment       APR-SEP        68        93    |      110        67    |       127       152            165
                                                                    |                       |
Rock Creek nr Arlington              APR-SEP      19.7        27    |       32        56    |        38        47             57
                                                                    |                       |
Seminoe Reservoir inflow             APR-JUL       233       324    |      386        48    |       515       706            800
                                     APR-SEP       278       363    |      420        49    |       537       710            860
                                                                    |                       |
==================================================================================================================================
                     UPPER NORTH PLATTE RIVER BASIN                     |             UPPER NORTH PLATTE RIVER BASIN
             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
========================================================================|=========================================================
SEMINOE                               1016.7    480.0    680.9    573.2 |   N PLATTE above Northgate    7        76        59
                                                                        |
                                                                        |   ENCAMPMENT RIVER            4        88        64
                                                                        |
                                                                        |   BRUSH CREEK                 5        83        70
                                                                        |
                                                                        |   MEDICINE BOW & ROCK CREEK   3        67        47
                                                                        |
                                                                        |   N PLATTE above Seminoe     19        80        62
                                                                        |
==================================================================================================================================
 * 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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