Lower North Platte River Basin (9)
April 2001

Snow
SWE for the North Platte River basin in Wyoming averages 75 percent of normal (86 % of last year). The Sweetwater drainage SWE is currently 46 percent (56 percent of last year). Deer and LaPrele Creek SWE is 86 percent of average (97 percent of last year. SWE for the North Platte above the Laramie River drainage is 75 percent of average (86 % of last year). SWE for the Laramie River above Laramie is 76 percent of average (82 % of last year). SWE for the Little Laramie River is 66 percent of average (91 percent of last year). SWE for the Laramie River above the mouth is 73 percent of average (84 % of last year). For more information see Basin Summary of Snow Courses at beginning of report.

Precipitation
Last months precipitation ranged from 10 to 74 percent for the 11 reporting stations. March precipitation for the basin was 45 percent of average (51 percent of last year). The water year-to-date precipitation for the basin is currently 70 percent of average (84 percent of last year). Year to date percentages range from 38 to 105.

Reservoir
The Lower North Platte River basin usable storage is average to well above average. Reservoir storage is as follows: Alcova 156,400 acre feet (97 percent of average); Glendo 395,000 acre feet (94 percent of average); Guernsey 18,600 acre feet (86 percent of average); Pathfinder 770,900 acre feet (125 percent of average); Seminoe 646,200 acre feet (176 percent of average). Wheatland No.2 45,000 acre feet (92 percent of average).. Water allocated to project use is near average with North Platte Project users at 103 percent of average, Kendrick Project users at 119 percent of average, and Glendo Project users at 120 percent of average.

Streamflow
Yields from 30 to 66 percent are expected in the basin during the forecast period. The following yields are based on the fifty percent chance probability runoff for the April through September forecast period. The Sweetwater near Alcova is forecast to yield about 22,000 acre-feet (30 percent of average). Deer Creek at Glenrock is expected to yield about 56 percent of average (22,000 acre-feet). LaPrele Creek above the reservoir is estimated to yield 64 percent of average (16,100 acre-feet). North Platte River below Guernsey Reservoir is expected to yield about 47 percent of normal (463,000 acre-feet), and below Glendo Reservoir is anticipated to yield about 48 percent of average (460,000 acre-feet). Laramie River near Woods should yield about 66 percent of average (89,000 acre-feet). The Little Laramie near Filmore should produce about 38,000 acre-feet (59 percent of average). 

==================================================================================================================================
                                      LOWER NORTH PLATTE, SWEETWATER & LARAMIE RIVER BASINS
                                               Streamflow Forecasts - April 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           APR-JUL       8.3      15.2    |       20        29    |        36        60             69
                                     APR-SEP       8.9      16.3    |       22        30    |        39        63             74
                                                                    |                       |
Deer Creek at Glenrock               APR-SEP      10.2      16.7    |       22        56    |        28        38             39
                                                                    |                       |
La Prele Creek ab La Prele Reservoir APR-SEP       4.0       9.9    |     16.1        64    |        25        42             25
                                                                    |                       |
North Platte River blw Glendo Reserv APR-JUL       182       338    |      445        48    |       552       708            925
                                     APR-SEP       182       348    |      460        48    |       572       738            958
                                                                    |                       |
North Platte River blw Guernsey Resv APR-JUL       291       385    |      447        48    |       580       775            938
                                     APR-SEP       305       404    |      463        47    |       601       803            985
                                                                    |                       |
Laramie River nr Woods               APR-SEP        26        63    |       89        66    |       115       152            135
                                                                    |                       |
Little Laramie River nr Filmore      APR-SEP        21        31    |       38        59    |        45        55             64
                                                                    |                       |
==================================================================================================================================
          LOWER NORTH PLATTE, SWEETWATER & LARAMIE RIVER BASINS         |  LOWER NORTH PLATTE, SWEETWATER & LARAMIE RIVER BASINS
             Reservoir Storage (1000 AF) - End of March                 |        Watershed Snowpack Analysis - April 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    156.4    156.8    162.0 |   SWEETWATER                  3        61        46
                                                                        |
GLENDO                                 506.4    395.9    463.6    420.3 |   DEER & LaPRELE CREEKS       4        97        86
                                                                        |
GUERNSEY                                45.6     18.6     18.6     21.6 |   N PLATTE abv Laramie R.    26        85        75
                                                                        |
PATHFINDER                            1016.5    770.9    994.9    619.0 |   LARAMIE RIVER abv Laramie   9        82        76
                                                                        |
SEMINOE                               1016.7    646.2    743.0    368.0 |   LITTLE LARAMIE RIVER        4        91        66
                                                                        |
WHEATLAND #2                            98.9     45.0     74.0     48.7 |   LARAMIE RIVER above mouth  12        84        73
                                                                        |
NORTH PLATTE PROJ                     1062.1    695.2   1065.2    676.0 |   NORTH PLATTE               34        86        75
                                                                        |
KENDRICK PROJECT                      1201.7    968.4    987.0    812.7 |
                                                                        |
GLENDO PROJECT USERS                   183.2    152.1    155.0    127.2 |
                                                                        |
==================================================================================================================================
 * 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.                  
(2) - The value is natural volume - actual volume may be affected by upstream water management.
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