Upper North Platte River Basin
February 1997

Snow
The 20 snow courses above Seminoe Reservoir average about 56 percent more than the normal Snow Water Equivalent (SWE) recorded for this time of the year. In Colorado (above Northgate), SWE is about 56 percent above average and 14 percent more than last year at this time. SWE in the Encampment River drainage is about 66 percent more than normal and 34 percent more than last year. Brush Creek SWE for the year is about 55 percent more than normal and 45 percent more than last year. The Medicine Bow and Rock Creek drainage SWE is about 42 percent above average and 31 percent above last year at this time. For more information see Basin Summary of Snow Courses at the beginning of this report.

Precipitation
Twelve reporting stations indicate January precipitation was 49 percent above average. January precipitation was about 9 percent less than last year's amount. Total precipitation, for the water year to date, is 48 percent more than average for the basin. Total precipitation for the water year is about 25 percent more than last year's amount.

Reservoirs
Seminoe Reservoir is currently storing about 51 percent more than normal for this time of the year; currently the reservoir is storing about 10 percent less than last year's storage. Seminoe Reservoir storage is estimated to be about 707,300 acre feet; last year the reservoir had 783,700 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 - February 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       355       421    |      465       172    |       509       575            271
                                                                    |                       |
ENCAMPMENT RIVER near Encampment     APR-SEP       197       220    |      235       151    |       250       273            156
                                                                    |                       |
NORTH PLATTE RIVER near Sinclair     APR-SEP      1012      1211    |     1300       181    |      1389      1558            718
                                                                    |                       |
ROCK CREEK nr Arlington              APR-SEP        64        77    |       85       147    |        94       106             58
                                                                    |                       |
MEDICINE BOW RIVER nr Hanna          APR-SEP       135       180    |      210       165    |       240       285            127
                                                                    |                       |
SEMINOE RESERVOIR INFLOW             APR-JUL      1165      1305    |     1400       175    |      1495      1635            800
                                                                    |                       |
==================================================================================================================================
                     UPPER NORTH PLATTE RIVER BASIN                     |             UPPER NORTH PLATTE RIVER BASIN
             Reservoir Storage (1000 AF) - End of January               |        Watershed Snowpack Analysis - February 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    707.3    783.7    467.0 |   N PLATTE above Northgate    8       114       156
                                                                        |
                                                                        |   ENCAMPMENT RIVER            4       134       166
                                                                        |
                                                                        |   BRUSH CREEK                 5       145       155
                                                                        |
                                                                        |   MEDICINE BOW & ROCK CREEK   3       131       142
                                                                        |
                                                                        |   N PLATTE above Seminoe     20       126       156
                                                                        |
==================================================================================================================================
 * 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.
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