Lower North Platte River Basin (9)
March 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 (63 % of last year). Deer and LaPrele Creeks are currently at 91 percent of average (55 % of last year). The Sweetwater drainage is currently 70 percent (45 % of last year). The North Platte above the Laramie River drainage is 88 percent of average (61 % of last year). The Laramie River above Laramie is 88 percent of average (73 % of last year). The Little Laramie River is 81 percent of average (59 % of last year). For more information see Basin Summary of Snow Courses at beginning of report.

Precipitation
Of the reporting stations, South Pass SNOTEL had the least precipitation, with 63 percent of average for the month. Albin reported the most, at 275 percent of the February average. February precipitation for the basin was 99 percent of average (105 percent of last year). The water year-to-date precipitation for the basin is currently 94 percent of average (63 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 157,600 acre feet (100 percent of average), Glendo 447,900 acre feet (117 percent of average), Guernsey 24,300 acre feet (179 percent of normal), Pathfinder 971,400 acre feet (165 percent of average), Seminoe 837,500 acre feet (205 percent of average), and Wheatland No. Two 63,000 acre feet (146 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 64 percent of average (25,000 acre feet). Below Guernsey, the North Platte River should flow near 88 percent of average (870,000 acre feet). The Sweetwater is forecast to flow 60,000 acre feet (80 percent of average). LaPrele Creek should yield 56 percent of average (14,000 acre feet). North Platte below Glendo should yield about 87 percent of average (840,000 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 - March 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      12.5        38    |       55        80    |        72        98             69
                                     APR-SEP      15.6        42    |       60        81    |        78       104             74
                                                                    |                       |
Deer Creek at Glenrock               APR-SEP      10.3      18.3    |       25        64    |        33        46             39
                                                                    |                       |
La Prele Creek ab La Prele Reservoir APR-JUL       2.2       7.5    |     14.0        56    |        23        44             25
                                                                    |                       |
NORTH PLATTE RIVER blw Glendo        APR-SEP       462              |      840        87    |                1300            963
                                                                    |                       |
NORTH PLATTE R. blw Guernsey         APR-SEP       485              |      870        88    |                1335            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 February              |        Watershed Snowpack Analysis - March 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    157.6    158.0    157.1 |   SWEETWATER                  3        45        70
                                                                        |
GLENDO                                 506.4    447.9    373.3    383.1 |   DEER & LaPRELE CREEKS       4        55        91
                                                                        |
GUERNSEY                                45.6     24.3     17.9     13.6 |   N PLATTE abv Laramie R.    27        61        88
                                                                        |
PATHFINDER                            1016.5    971.4    889.0    590.0 |   LARAMIE RIVER abv Laramie   8        73        88
                                                                        |
SEMINOE                               1016.7    837.5    671.7    409.0 |   LITTLE LARAMIE RIVER        4        59        81
                                                                        |
WHEATLAND #2                            98.9     63.0     55.0     43.2 |   LARAMIE RIVER above mouth  11        67        85
                                                                        |
NORTH PLATTE PROJ                     1062.1   1030.2    811.3    633.3 |   NORTH PLATTE               34        63        88
                                                                        |
KENDRICK PROJECT                      1201.7   1006.7    979.8    818.1 |
                                                                        |
GLENDO PROJECT USERS                   183.2    158.1    160.0    126.8 |
                                                                        |
==================================================================================================================================
 * 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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