Upper North Platte River Basin (8)
January 2002

Snow
The snow courses above Seminoe Reservoir have about 66 percent of average snow water equivalent (SWE) recorded for this time of the year (72 percent of last year). SWE in the drainage area above Northgate is about 67 percent of average and 69 percent of last year at this time. SWE in the Encampment River drainage is about 74 percent of normal and 87 percent of last year. Brush Creek SWE for the year is about 55 percent of normal and 57 percent of last year's SWE. Medicine Bow and Rock Creek drainage SWE is about 54 percent of average and 63 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 December precipitation was 70 percent of average and about 68 percent of last year's amount. December precipitation varied from 11 to 84 percent of average. Total water-year-to-date precipitation is about 73 percent of average for the basin, which is about 91 percent of last year's amount. Year to date percentage ranges from 30 to 107 percent of average for the 11 reporting stations.

Reservoirs
Seminoe Reservoir is currently storing about 76 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 480,400 acre-feet (47 percent of capacity). Last year, at this time, the reservoir had 717,900 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 165,000 acre-feet (61 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 44,000 acre-feet (77 percent of average). Seminoe Reservoir inflow should be about (495,000 acre-feet (58 percent of normal). See the following table for more detailed information on projected runoff. 

==================================================================================================================================
                                                  UPPER NORTH PLATTE RIVER BASIN
                                               Streamflow Forecasts - January 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        76       106    |      165        61    |       224       311            270
                                                                    |                       |
Encampment River nr Encampment       APR-SEP        62        81    |      110        67    |       139       182            165
                                                                    |                       |
Rock Creek nr Arlington              APR-SEP        26        36    |       44        77    |        53        67             57
                                                                    |                       |
Seminoe Reservoir inflow             APR-JUL       220       360    |      455        57    |       622       868            800
                                     APR-SEP       277       407    |      495        58    |       647       871            860
                                                                    |                       |
==================================================================================================================================
                     UPPER NORTH PLATTE RIVER BASIN                     |             UPPER NORTH PLATTE RIVER BASIN
             Reservoir Storage (1000 AF) - End of December              |        Watershed Snowpack Analysis - January 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    480.4    717.9    631.1 |   N PLATTE above Northgate    5        69        67
                                                                        |
                                                                        |   ENCAMPMENT RIVER            3        87        74
                                                                        |
                                                                        |   BRUSH CREEK                 2        57        55
                                                                        |
                                                                        |   MEDICINE BOW & ROCK CREEK   2        63        54
                                                                        |
                                                                        |   N PLATTE above Seminoe     13        72        66
                                                                        |
==================================================================================================================================
 * 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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