Upper North Platte River Basin (8)
January 1998

Snow
The 13 snow courses above Seminoe Reservoir average about 35 percent less than the normal Snow Water Equivalent (SWE) recorded for this time of the year. In Colorado (above Northgate), SWE is about 31 percent below average and 46 percent of last year at this time. SWE in the Encampment River drainage is about 54 percent of normal and 35 percent of last year. Brush Creek SWE for the year is about 81 percent of normal and 50 percent of last year's SWE. The Medicine Bow and Rock Creek drainage SWE is about 62 percent of average and 42 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 December precipitation was 42 percent below average and about 71 percent less than last year's amount. December precipitation varied from 24 percent of average at South Brush Creek SNOTEL to 107 percent of average at Reno Hill SNOTEL. Total precipitation, for the water year to date, is 76 percent of average for the basin. Total precipitation for the water year is about 50 percent of last year's amount.

Reservoirs
Seminoe Reservoir is currently storing about 62 percent more than normal for this time of the year; currently the reservoir is storing about 18 percent more than last year's storage. Seminoe Reservoir storage is estimated to be about 876,000 acre feet; last year the reservoir had 744,800 acre feet in storage.

Streamflow
The entire drainage basin is expected to have a below average runoff. The April through September 50 percent chance yield for the North Platte River near the Colorado state line is expected to be 195,000 acre feet (about 38 percent less than normal); the Encampment River near Encampment is estimated to yield 103,000 acre feet (34 percent below normal); the North Platte River near Sinclair will yield about 490,000 acre feet (about 32 percent below normal); Rock Creek near Arlington is estimated to yield 47,000 acre feet (about 16 percent below average); Medicine Bow River above Seminoe Reservoir is expected to yield about 76,000 acre feet (about 40 percent below normal), Seminoe Reservoir inflow should be about (575,000 acre feet (32 percent below normal). See the following table for more detailed information on projected runoff. 

==================================================================================================================================
                                                  UPPER NORTH PLATTE RIVER BASIN
                                               Streamflow Forecasts - January 1, 1998
==================================================================================================================================
                                              |  <<====== 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        79       135    |      195        72    |       255       342            271
                                                                    |                       |
Encampment River nr Encampment       APR-SEP        55        74    |      103        66    |       132       175            156
                                                                    |                       |
North Platte River nr Sinclair       APR-SEP       259       337    |      490        68    |       643       867            719
                                                                    |                       |
Rock Creek nr Arlington              APR-SEP        28        39    |       47        84    |        56        71             56
                                                                    |                       |
Medicine Bow River ab Seminoe Reserv APR-SEP        28        50    |       76        60    |       108       165            127
                                                                    |                       |
Seminoe Reservoir Inflow             APR-JUL       284       363    |      530        67    |       697       943            788
                                     APR-SEP       315       395    |      575        68    |       755      1020            851
                                                                    |                       |
==================================================================================================================================
                     UPPER NORTH PLATTE RIVER BASIN                     |             UPPER NORTH PLATTE RIVER BASIN
             Reservoir Storage (1000 AF) - End of December              |        Watershed Snowpack Analysis - January 1, 1998
==================================================================================================================================
                                      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    876.0    744.8    542.0 |   N PLATTE above Northgate    5        46        69
                                                                        |
                                                                        |   ENCAMPMENT RIVER            3        35        54
                                                                        |
                                                                        |   BRUSH CREEK                 2        50        81
                                                                        |
                                                                        |   MEDICINE BOW & ROCK CREEK   2        42        62
                                                                        |
                                                                        |   N PLATTE above Seminoe     13        42        65
                                                                        |
==================================================================================================================================
 * 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.
To January 1998 Basin Outlook Report Contents Page