Upper North Platte River Basin (8)
February 2001

Snow
The snow courses above Seminoe Reservoir have about 77 percent of average snow water equivalent (SWE) recorded for this time of the year (95 percent of last year). SWE in the drainage area above Northgate is about 78 percent of average and 88 percent of last year at this time. SWE in the Encampment River drainage is about 71 percent of normal and 96 percent of last year. Brush Creek SWE for the year is about 87 percent of normal and 103 percent of last year's SWE. Medicine Bow and Rock Creek drainage SWE is about 66 percent of average and 99 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 January precipitation was 57 percent of average and about 44 percent of last year's amount. January precipitation varied from 2 to 400 percent of average. Total water-year-to-date precipitation is about 76 percent of average for the basin, which is about 99 percent of last year's amount. Year to date percentage ranges from 38 to 100 percent of average for the 9 reporting stations.

Reservoirs
Seminoe Reservoir is currently storing about 146 percent of normal for this time of the year. The reservoir is storing 82 percent of last year's amount. Seminoe Reservoir is estimated to be storing 680,900 acre-feet (67 percent of capacity). Last year, at this time, the reservoir had 830,100 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 190,000 acre-feet (70 percent of average). Encampment River near Encampment is estimated to yield 110,000 acre-feet (71 percent of normal). Rock Creek near Arlington is estimated to yield 39,000 acre-feet (70 percent of average). Seminoe Reservoir inflow should be about (585,000 acre-feet (69 percent of normal). See the following table for more detailed information on projected runoff. 

==================================================================================================================================
                                                  UPPER NORTH PLATTE RIVER BASIN
                                               Streamflow Forecasts - February 1, 2001
==================================================================================================================================
                                              |  <<====== 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        78       145    |      190        70    |       235       302            271
                                                                    |                       |
Encampment River nr Encampment       APR-SEP        68        93    |      110        71    |       127       152            156
                                                                    |                       |
Rock Creek nr Arlington              APR-SEP        25        33    |       39        70    |        45        56             56
                                                                    |                       |
Seminoe Reservoir inflow             APR-JUL       323       449    |      540        69    |       669       860            788
                                     APR-SEP       349       485    |      585        69    |       702       875            851
                                                                    |                       |
==================================================================================================================================
                     UPPER NORTH PLATTE RIVER BASIN                     |             UPPER NORTH PLATTE RIVER BASIN
             Reservoir Storage (1000 AF) - End of January               |        Watershed Snowpack Analysis - February 1, 2001
==================================================================================================================================
                                      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    680.9    830.1    467.0 |   N PLATTE above Northgate    7        88        78
                                                                        |
                                                                        |   ENCAMPMENT RIVER            4        96        71
                                                                        |
                                                                        |   BRUSH CREEK                 5       103        87
                                                                        |
                                                                        |   MEDICINE BOW & ROCK CREEK   3        99        66
                                                                        |
                                                                        |   N PLATTE above Seminoe     19        95        77
                                                                        |
==================================================================================================================================
 * 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.

(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.
To February 2001 Basin Outlook Report Contents Page