Lower North Platte River Basin
May 1997

Snow
Higher than normal snowfall across the basin has caused near record snow water equivalent (SWE). Deer and LaPrele Creeks are currently at 177 percent of average. The Sweetwater drainage is 142 percent. The North Platte above the Laramie river drainage is 35 percent above average. The basin average SWE is now 134 percent of normal. This is 10 percent ahead of what it was last year at this time. For more information see Basin Summary of Snow Courses at beginning of report.

Precipitation
April precipitation in the basin varied quite a lot. Of the reporting stations, Double 4 Ranch came in with 54 percent of average precipitation for the month, while Pathfinder Dam reported 235 percent of the April average. April precipitation for the basin was 115 percent of average (92 percent of last year). The water year-to-date precipitation for the basin is currently 122 percent of average (8 percent ahead 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 180,700 acre feet (100 percent of average), Glendo 488,100 acre feet (107 percent of average), Guernsey 31,000 acre feet (95 percent of normal), Pathfinder 922,200 acre feet (151 percent of average), Seminoe 611,000 acre feet (156 percent of average), and Wheatland No. Two 71,000 acre feet (129 percent of average).

Streamflow
At this time, above average yields are expected over the entire basin during the April to 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 139 percent of average (54,000 acre feet). Below Guernsey, the North Platte River should flow near 129 percent of average (1,280,000 acre feet). The Sweetwater is forecast to flow 130,000 acre feet (178 percent of average). LaPrele Creek should yield 128 percent of average (32,000 acre feet). North Platte below Glendo should yield about 128 percent of average (1,230,000 acre feet). Laramie River near Woods should yield about 122 percent of average (165,000 acre feet). The Little Laramie near Filmore should flow 80,000 acre feet (125 percent of average). 

==================================================================================================================================
                                      LOWER NORTH PLATTE, SWEETWATER & LARAMIE RIVER BASINS
                                               Streamflow Forecasts - May 1, 1997
==================================================================================================================================
                                              |  <<====== 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)
====================================================================|=======================|=====================================
SEMINOE RESERVOIR INFLOW             APR-JUL       974      1049    |     1100       138    |      1151      1226            800
                                                                    |                       |
SWEETWATER RIVER nr Alcova           APR-JUL        90       108    |      120       174    |       133       154             69
                                     APR-SEP       103       119    |      130       178    |       141       158             73
                                                                    |                       |
DEER CREEK at Glenrock               APR-SEP        36        47    |       54       139    |        61        72             39
                                                                    |                       |
LaPRELE CREEK above Reservoir        APR-SEP        21        27    |       32       128    |        37        43             25
                                                                    |                       |
NORTH PLATTE RIVER blw Glendo        APR-SEP      1059              |     1230       128    |                1502            963
                                                                    |                       |
NORTH PLATTE R. blw Guernsey         APR-SEP      1098              |     1280       129    |                1563            989
                                                                    |                       |
LARAMIE RIVER near Woods             APR-SEP       129       150    |      165       122    |       180       201            135
                                                                    |                       |
LITTLE LARAMIE RIVER near Filmore    APR-SEP        67        75    |       80       125    |        85        93             64
                                                                    |                       |
==================================================================================================================================
          LOWER NORTH PLATTE, SWEETWATER & LARAMIE RIVER BASINS         |  LOWER NORTH PLATTE, SWEETWATER & LARAMIE RIVER BASINS
             Reservoir Storage (1000 AF) - End of April                 |        Watershed Snowpack Analysis - May 1, 1997
==================================================================================================================================
                                      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    180.7    180.3    179.9 |   SWEETWATER                  4       138       142
                                                                        |
GLENDO                                 506.4    488.1    492.9    457.6 |   DEER & LaPRELE CREEKS       3       122       177
                                                                        |
GUERNSEY                                45.6     31.0     31.5     32.8 |   N PLATTE abv Laramie R.    27       111       135
                                                                        |
PATHFINDER                            1016.5    922.2    928.7    609.0 |   LARAMIE RIVER abv Laramie   9        98       128
                                                                        |
SEMINOE                               1016.7    611.0    627.5    392.0 |   LITTLE LARAMIE RIVER        4       120       133
                                                                        |
WHEATLAND #2                            98.9     71.0     60.0     54.9 |   LARAMIE RIVER above mouth  12       104       130
                                                                        |
NORTH PLATTE PROJ                     1062.1   1047.3   1057.3    786.7 |   NORTH PLATTE               35       110       134
                                                                        |
KENDRICK PROJECT                      1201.7    819.4    828.2    807.0 |
                                                                        |
GLENDO PROJECT USERS                   183.2    167.2    172.2    128.9 |
                                                                        |
==================================================================================================================================
 * 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.
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