Lower North Platte River Basin (9)
June 2001

Snow
SWE for the North Platte River basin in Wyoming averages 17 percent of normal (80 % of last year). The Sweetwater drainage, Deer and LaPrele Creek are melted out. SWE for the North Platte above the Laramie River drainage is 27 percent of average (80 % of last year). SWE for the Laramie River above Laramie is 15 percent of average (43 % of last year). SWE for the Little Laramie River is 2 percent of average. SWE for the Laramie River above the mouth is 11 percent of average (44 % of last year). For more information see Basin Summary of Snow Courses at beginning of report.

Precipitation
Last months precipitation ranged from 12 to 189 percent for the 10 reporting stations. May precipitation for the basin was 85 percent of average (74 percent of last year). The water year-to-date precipitation for the basin is currently 82 percent of average (87 percent of last year). Year to date percentages range from 42 to 127.

Reservoir
The Lower North Platte River basin usable storage is average to well above average. Reservoir storage is as follows: Alcova 180,000 acre feet (100 percent of average); Glendo 444,800 acre feet (89 percent of average); Guernsey 35,600 acre feet (103 percent of average); Pathfinder 797,900 acre feet (125 percent of average); Seminoe 751,100 acre feet (136 percent of average). Wheatland No.2 61,000 acre feet (112 percent of average).. Water allocated to project use is near average with North Platte Project users at 99 percent of average, Kendrick Project users at 112 percent of average, and Glendo Project users at 115 percent of average.

Streamflow
The fifty-percent chance June through September runoff in the Lower North Platte River basin is forecast much below average. Irrigators without a storage facility may experience water shortage. Yields from 34 to 73 percent are expected in the basin during the forecast period. The following yields are based on the fifty percent chance probability runoff for the June through September forecast period. The Sweetwater near Alcova is forecast to yield about 13,400 acre-feet (37 percent of average). Deer Creek at Glenrock is expected to yield about 63 percent of average (4,600 acre-feet). LaPrele Creek above the reservoir is estimated to yield 34 percent of average (2,100 acre-feet). North Platte River below Guernsey Reservoir is expected to yield about 48 percent of normal (230,000 acre-feet), and below Glendo Reservoir is anticipated to yield about 47 percent of average (210,000 acre-feet). Laramie River near Woods should yield about 73 percent of average (65,000 acre-feet). The Little Laramie near Filmore should produce about 24,000 acre-feet (50 percent of average). 

==================================================================================================================================
                                      LOWER NORTH PLATTE, SWEETWATER & LARAMIE RIVER BASINS
                                               Streamflow Forecasts - June 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)
====================================================================|=======================|=====================================
Sweetwater River nr Alcova           JUN-JUL       8.3       9.8    |     10.8        35    |      14.9        21             31
                                     JUN-SEP      11.0      12.4    |     13.4        37    |      16.7        22             36
                                                                    |                       |
Deer Creek at Glenrock               JUN-SEP      1.80      3.31    |     4.60        63    |      6.10      8.70           7.25
                                                                    |                       |
La Prele Creek ab La Prele Reservoir JUN-SEP      0.46      1.24    |     2.10        34    |      3.28      5.71           6.20
                                                                    |                       |
North Platte River blw Glendo Reserv JUN-JUL       158       180    |      195        47    |       240       307            419
                                     JUN-SEP       171       194    |      210        47    |       258       328            451
                                                                    |                       |
North Platte River blw Guernsey Resv JUN-JUL       163       191    |      210        49    |       264       344            433
                                     JUN-SEP       179       209    |      230        48    |       289       377            479
                                                                    |                       |
Laramie River nr Woods               JUN-SEP        36        53    |       65        73    |        77        94             89
                                                                    |                       |
Little Laramie River nr Filmore      JUN-SEP      15.3        21    |       24        50    |        28        33             48
                                                                    |                       |
==================================================================================================================================
          LOWER NORTH PLATTE, SWEETWATER & LARAMIE RIVER BASINS         |  LOWER NORTH PLATTE, SWEETWATER & LARAMIE RIVER BASINS
             Reservoir Storage (1000 AF) - End of May                   |        Watershed Snowpack Analysis - June 1, 2001
==================================================================================================================================
                                      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    180.0    180.7    180.4 |   SWEETWATER                  1         0         0
                                                                        |
GLENDO                                 506.4    444.8    507.1    501.0 |   DEER & LaPRELE CREEKS       2         0         0
                                                                        |
GUERNSEY                                45.6    473.8     35.9     34.5 |   N PLATTE abv Laramie R.    16        80        27
                                                                        |
PATHFINDER                            1016.5    797.9    993.1    638.0 |   LARAMIE RIVER abv Laramie   3        43        15
                                                                        |
SEMINOE                               1016.7    751.1    914.2    551.0 |   LITTLE LARAMIE RIVER        1         0         2
                                                                        |
WHEATLAND #2                            98.9     61.0     81.0     54.6 |   LARAMIE RIVER above mouth   4        44        11
                                                                        |
NORTH PLATTE PROJ                               NO REPORT               |   NORTH PLATTE               17        80        27
                                                                        |
KENDRICK PROJECT                                NO REPORT               |
                                                                        |
GLENDO PROJECT USERS                            NO REPORT               |
                                                                        |
==================================================================================================================================
 * 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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