Upper North Platte River Basin
January 1997

Snow
The 14 snow courses above Seminoe Reservoir average about 52 percent more than the normal Snow Water Equivalent) SWE recorded for this time of the year. In Colorado (above Northgate), SWE is about 50 percent above average and 129 percent of last year at this time. SWE in the Encampment River drainage is about 57 percent more than normal and 174 percent of last year. Brush Creek SWE for the year is about 64 percent more than normal and 138 percent of last year. The Medicine Bow and Rock Creek drainage SWE is about 47 percent above average and 147 percent of last year at this time. For more information see Basin Summary of Snow Courses at the beginning of this report.

Precipitation
Fourteen reporting stations indicate December precipitation was more than average (99 percent above average) over most of the Upper North Platte River basin. December precipitation was about 273 percent of last year's amount. Total precipitation, for the water year to date, is 49 percent more than average for the basin. Total precipitation for the water year is about 142 percent of last year's amount.

Reservoirs
Seminoe Reservoir is currently storing about 37 percent more than normal for this time of the year; currently the reservoir is storing about 7 percent less than year's storage . Seminoe Reservoir storage is estimated to be about 744,800 acre feet; last year the reservoir had 804,800 acre feet in storage.

Streamflow
The entire drainage basin is expected to have an above average runoff. The 50 percent chance yield for the North Platte River near the Colorado state line is expected to be about 49 percent more than normal (about 405,000 acre feet). The 50 percent chance yield for the Encampment River near Encampment is expected to be about 235,000 acre feet (51 percent above normal). The North Platte River near Sinclair is expected to yield about 960,000 acre feet (34 percent above normal). Rock Creek near Arlington is expected to yield about 67,000 acre feet (16 percent above average). The 50 percent chance yield for Medicine Bow River near Hanna is forecast to be about 210,000 acre feet (65 percent above normal). See the following table for more detailed information on projected runoff. 

==================================================================================================================================
                                                  UPPER NORTH PLATTE RIVER BASIN
                                               Streamflow Forecasts - January 1, 1997
==================================================================================================================================
                                              |  <<====== 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 near Northgate    APR-SEP       264       348    |      405       149    |       462       546            271
                                                                    |                       |
ENCAMPMENT RIVER near Encampment     APR-SEP       175       211    |      235       151    |       259       295            156
                                                                    |                       |
NORTH PLATTE RIVER near Sinclair     APR-SEP       625       858    |      960       134    |      1062      1235            718
                                                                    |                       |
ROCK CREEK nr Arlington              APR-SEP        45        58    |       67       116    |        76        89             58
                                                                    |                       |
MEDICINE BOW RIVER nr Hanna          APR-SEP       131       178    |      210       165    |       242       289            127
                                                                    |                       |
==================================================================================================================================
                     UPPER NORTH PLATTE RIVER BASIN                     |             UPPER NORTH PLATTE RIVER BASIN
             Reservoir Storage (1000 AF) - End of December              |        Watershed Snowpack Analysis - January 1, 1997
==================================================================================================================================
                                      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    744.8    804.8    542.0 |   N PLATTE above Northgate    5       129       150
                                                                        |
                                                                        |   ENCAMPMENT RIVER            3       174       157
                                                                        |
                                                                        |   BRUSH CREEK                 2       138       164
                                                                        |
                                                                        |   MEDICINE BOW & ROCK CREEK   2       147       147
                                                                        |
                                                                        |   N PLATTE above Seminoe     13       145       152
                                                                        |
==================================================================================================================================
 * 90%, 70%, 30%, and 10% chances of exceeding are the probabilities that the actual flow 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 flow - actual flow may be affected by upstream water management.
To Jaunary 1997 Basin Outlook Report Contents Page