Lower North Platte River Basin (9)
February 1998

Snow
Most areas in the basin have received less than normal snow for this time of year. The Lower North Platte River averages 88 percent of normal (56 % of last year). Deer and LaPrele Creeks are currently at 100 percent of average (57 % of last year). The Sweetwater drainage is currently 78 percent (43 % of last year). The North Platte above the Laramie River drainage is 86 percent of average (54 % of last year). The Laramie River above Laramie is 91 percent of average (66 % of last year). The Little Laramie River is 86 percent of average (55 % of last year). For more information see Basin Summary of Snow Courses at beginning of report.

Precipitation
Of the reporting stations, Pole Mountain had the least precipitation, with 57 percent of average precipitation for the month, while Bates Creek reported the most, at 208 percent of the January average. January precipitation for the basin was 119 percent of average (76 percent of last year). The water year-to-date precipitation for the basin is currently 91 percent of average (54 percent of last year).

Reservoir
Basin Reservoir storage is in good shape. Storage at all of the reservoirs is near average to well above average. Reservoir storage is as follows: Alcova 155,800 acre feet (100 percent of average), Glendo 410,600 acre feet (124 percent of average), Guernsey 15,900 acre feet (234 percent of normal), Pathfinder 946,800 acre feet (171 percent of average), Seminoe 855,100 acre feet (183 percent of average), and Wheatland No. Two 63,000 acre feet (157 percent of average).

Streamflow
At this time, below average yields are expected over the entire basin during the April through September forecast period. All the following values are based on the fifty percent chance probability runoff. The Deer Creek drainage is expected to flow at 56 percent of average (22,000 acre feet). Below Guernsey, the North Platte River should flow near 78 percent of average (773,000 acre feet). The Sweetwater is forecast to flow 56,000 acre feet (76 percent of average). LaPrele Creek should yield 60 percent of average (15,000 acre feet). North Platte below Glendo should yield about 77 percent of average (743,000 acre feet). Laramie River near Woods should yield about 86 percent of average (116,000 acre feet). The Little Laramie near Filmore should flow 56,000 acre feet (88 percent of average). 

==================================================================================================================================
                                      LOWER NORTH PLATTE, SWEETWATER & LARAMIE RIVER BASINS
                                               Streamflow Forecasts - February 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)
====================================================================|=======================|=====================================
Sweetwater River nr Alcova           APR-JUL        20        33    |       51        74    |        69        97             69
                                     APR-SEP        22        37    |       56        76    |        75       103             74
                                                                    |                       |
Deer Creek at Glenrock               APR-SEP       6.6      14.7    |       22        56    |        31        46             39
                                                                    |                       |
La Prele Creek ab La Prele Reservoir APR-SEP       2.5       8.2    |     15.0        60    |        25        46             25
                                                                    |                       |
NORTH PLATTE RIVER blw Glendo        APR-SEP       366              |      743        77    |                1194            963
                                                                    |                       |
NORTH PLATTE R. blw Guernsey         APR-SEP       386              |      773        78    |                1236            989
                                                                    |                       |
Laramie River nr Woods               APR-SEP        50        89    |      116        86    |       143       182            135
                                                                    |                       |
Little Laramie River nr Filmore      APR-SEP        35        48    |       56        88    |        64        77             64
                                                                    |                       |
==================================================================================================================================
          LOWER NORTH PLATTE, SWEETWATER & LARAMIE RIVER BASINS         |  LOWER NORTH PLATTE, SWEETWATER & LARAMIE RIVER BASINS
             Reservoir Storage (1000 AF) - End of January               |        Watershed Snowpack Analysis - February 1, 1998
==================================================================================================================================
                                      Usable |  *** Usable Storage ***  |                            Number     This Year as % of
Reservoir                            Capacity|  This      Last          |   Watershed                  of       =================
                                             |  Year      Year     Avg  |                          Data Sites   Last Yr   Average
========================================================================|=========================================================
ALCOVA                                 184.3    155.8    155.8    156.1 |   SWEETWATER                  3        43        78
                                                                        |
GLENDO                                 506.4    410.6    315.9    330.8 |   DEER & LaPRELE CREEKS       4        57       100
                                                                        |
GUERNSEY                                45.6     15.9     15.0      6.8 |   N PLATTE abv Laramie R.    19        54        87
                                                                        |
PATHFINDER                            1016.5    946.8    861.9    553.0 |   LARAMIE RIVER abv Laramie   3        75       108
                                                                        |
SEMINOE                               1016.7    855.1    707.3    467.0 |   LITTLE LARAMIE RIVER        4        55        86
                                                                        |
WHEATLAND #2                            98.9     63.0     51.0     40.1 |   LARAMIE RIVER above mouth   6        59        92
                                                                        |
NORTH PLATTE PROJ                     1062.1   1028.9    764.3    601.0 |   NORTH PLATTE               24        55        89
                                                                        |
KENDRICK PROJECT                      1201.7   1005.9    981.3    819.1 |
                                                                        |
GLENDO PROJECT USERS                   183.2    154.3    149.6    119.8 |
                                                                        |
==================================================================================================================================
 * 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.
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