Lower North Platte River Basin (9)
January 1998

Snow
Most areas in the basin have received less than normal snow for this time of year. The lower North Platte River averages 68 percent of normal (44 % of last year). Deer and LaPrele Creeks are currently at 94 percent of average (48 % of last year). The Sweetwater drainage is currently just 69 percent (34 % of last year). The North Platte above the Laramie River drainage is 67 percent above average (42 % of last year). The Laramie River drainage averages 75 percent of normal (53 % of last year) and the Laramie River above Laramie is 85 percent of average (64 % of last year). The Little Laramie River is about 54 percent of average (34 % of last year). For more information see Basin Summary of Snow Courses at beginning of report.

Precipitation
Of the reporting stations, Brooklyn Lake had the least precipitation, with 12 percent of average precipitation for the month, while Pathfinder Dam reported the most, at 183 percent of the December average. December precipitation for the basin was 89 percent of average (37 percent of last year). The water year-to-date precipitation for the basin is currently 84 percent of average (49 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 156,200 acre feet (102 percent of average), Glendo 364,500 acre feet (132 percent of average), Guernsey 12,800 acre feet (233 percent of normal), Pathfinder 920,000 acre feet (182 percent of average), Seminoe 876,000 acre feet (162 percent of average), and Wheatland No. Two 63,000 acre feet (average not established).

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 44 percent of average (17,000 acre feet). Below Guernsey, the North Platte River should flow near 64 percent of average (635,000 acre feet). The Sweetwater is forecast to flow 48,000 acre feet (65 percent of average). LaPrele Creek should yield 40 percent of average (10,000 acre feet). North Platte below Glendo should yield about 63 percent of average (610,000 acre feet). Laramie River near Woods should yield about 86 percent of average (116,000 acre feet). The Little Laramie near Filmore should flow 50,000 acre feet (78 percent of average). 

==================================================================================================================================
                                      LOWER NORTH PLATTE, SWEETWATER & LARAMIE RIVER BASINS
                                               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)
====================================================================|=======================|=====================================
Sweetwater River nr Alcova           APR-JUL      18.3        29    |       45        65    |        62        86             69
                                     APR-SEP      18.9        31    |       48        65    |        65        90             74
                                                                    |                       |
Deer Creek at Glenrock               APR-SEP       4.7      10.4    |     17.0        44    |        25        40             39
                                                                    |                       |
La Prele Creek ab La Prele Reservoir APR-SEP       0.8       4.6    |     10.0        40    |      18.5        38             25
                                                                    |                       |
NORTH PLATTE RIVER blw Glendo        APR-SEP       318              |      610        63    |                1156            963
                                                                    |                       |
NORTH PLATTE R. blw Guernsey         APR-SEP       326              |      635        64    |                1197            989
                                                                    |                       |
Laramie River nr Woods               APR-SEP        46        88    |      116        86    |       144       186            135
                                                                    |                       |
Little Laramie River nr Filmore      APR-SEP        26        40    |       50        78    |        60        74             64
                                                                    |                       |
==================================================================================================================================
          LOWER NORTH PLATTE, SWEETWATER & LARAMIE RIVER BASINS         |  LOWER NORTH PLATTE, SWEETWATER & LARAMIE RIVER BASINS
             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
========================================================================|=========================================================
ALCOVA                                 184.3    156.2    154.4    153.1 |   SWEETWATER                  1        34        69
                                                                        |
GLENDO                                 506.4    364.5    257.2    276.4 |   DEER & LaPRELE CREEKS       2        48        94
                                                                        |
GUERNSEY                                45.6     12.8     11.7      5.5 |   N PLATTE abv Laramie R.    16        42        67
                                                                        |
PATHFINDER                            1016.5    920.0    831.8    505.0 |   LARAMIE RIVER abv Laramie   3        64        85
                                                                        |
SEMINOE                               1016.7    876.0    744.8    542.0 |   LITTLE LARAMIE RIVER        1        34        54
                                                                        |
WHEATLAND #2                            98.9     63.0     48.0      --- |   LARAMIE RIVER above mouth   4        53        75
                                                                        |
NORTH PLATTE PROJ                     1062.1    948.8    706.9    568.4 |   NORTH PLATTE               17        44        68
                                                                        |
KENDRICK PROJECT                      1201.7   1007.1    982.7    819.8 |
                                                                        |
GLENDO PROJECT USERS                   183.2    154.6    150.1    116.2 |
                                                                        |
==================================================================================================================================
 * 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.
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