Wyoming Water Supply Outlook Report
March 2001

General
Generally, snow water equivalent (SWE) across the state is much below normal for this time of the year. SWE averages for the State are about 67 percent of normal for this time of the year. Northwest portion of the State is 56 of percent normal. Northeast Wyoming is 71 of percent of normal, and the southeast part of the State is 80 percent of average. Southwestern Wyoming is 71 percent of average for this time of the year.

Precipitation for February was generally below average for the State. Year-to- date precipitation is below average for all except the Belle Fourche drainage - this area is still feeling the effects of the heavy snow last fall. Reservoir levels vary from about 30 percent of average to 159 percent of average. Generally, the larger capacity reservoirs are above average storage. Forecast runoff varies from 33 to 103 percent of average. The mean of all the forecast points in the State is about 62 percent of average (38 percent below average).

Snowpack
Near average snow during the month of February kept most of the SWE percentages almost the same as last month. SWE is generally below average for the entire State. SWE in the northwestern portion of the State is now at 56 percent of average (65 percent of last year). Northeast Wyoming SWE is currently about 71 percent of average (88 percent of last year). The southeast portion is currently about 80 percent of average SWE (88 percent of last year). And the southwest is about 71 percent of average (79 percent of last year).

Precipitation
February precipitation was below normal over the State, except in the Black Hills. The Belle Fourche received 113 percent of normal for February. This was the bright spot in the state as far as precipitation goes. Most of the basins received less than 80 percent of average precipitation. The following table displays the major river basins and their departure from normal for this month.

BasinDeparture
from normal
BasinDeparture
from normal
Snake River -30%Upper North Platte River-04%
Yellowstone & Madison -22%Lower North Platte River-20%
Wind River -27%Little Snake River -25%
Bighorn -20%Upper Green River -27%
Shoshone & Clarks Fork -10%Lower Green River -27%
Powder & Tongue River -26%Upper Bear River -24%
Belle Fourche & Cheyenne+13%

Streams
Stream flow yield is expected to be below average across the State. Most probable yield for the State is forecast to be about 62 percent of average (varies from 33 to 103 percent of average). The northwest part of the State is expected to yield about 57 percent of normal -- yield estimates vary from 33 to 73 percent of normal through the northwest region of the State. Yield from the northeast portion of Wyoming will be below average (about 54 percent of average) -- yield estimates vary from 47 to 64 percent of average for the various forecast points. The southeast portion of the state will be about 76 percent of normal -- yield estimates range from 61 to 103 percent of normal. The southwest portion of Wyoming varies from 33 to 77 percent of average -- mean estimated yield for the forecast points in southwest Wyoming is about 65 percent of average.

Reservoirs
Although several reservoirs did not report, reservoir storage for those reporting is generally above average for this time of the year. See following table for further information about reservoir storage.

Major Reservoirs in Wyoming


                             B A S I N    W I D E
                      R E S E R V O I R    S U M M A R Y

                        FOR THE END OF FEBRUARY 2001


 BASIN AREA         CURRENT AS  LAST YR AS  AVERAGE AS  CURRENT AS  CURRENT AS
  RESERVIOR         % CAPACITY  % CAPACITY  % CAPACITY   % AVERAGE   % LAST YR
--------------------------------------------------------------------------------
ALCOVA                    85          85          85         100         100
ANGOSTURA                 74          93          83          89          80
BELLE FOURCHE             87          97          63         137          89
BIG SANDY                 14           0          48          30           0
BIGHORN LAKE              62          69          60         104          90
BOYSEN                    73          88          93          78          82
BUFFALO BILL              56          68          61          93          82
BULL LAKE                 41          63          56          74          66
DEERFIELD                 99          97          87         114         103
EDEN                       0           0          35           0           0
FLAMING GORGE                       AVERAGE NOT ESTABLISHED
FONTENELLE                28          38          50          56          73
GLENDO                    64          75          76          85          85
GRASSY LAKE               84          82          72         116         102
GUERNSEY                  34          35          30         112          96
HEBGEN LAKE               78          85          66         119          92
JACKSON LAKE              75          77          57         133          98
KEYHOLE                   82          90          53         157          92
PACTOLA                   98          98          84         118         100
PALISADES                 50          89          76          65          56
PATHFINDER                74          94          58         128          78
PILOT BUTTE               74          71          56         132         104
SEMINOE                   64          79          40         159          81
SHADEHILL                 49          66          61          79          74
TONGUE RIVER              49          54          44         111          91
VIVA NAUGHTON RES         73          81          66         112          90
WHEATLAND #2              34          71          44          79          49
WOODRUFF NARROWS                    AVERAGE NOT ESTABLISHED
GLENDO PROJECT USERS      74          84          69         107          88
KENDRICK PROJECT          81          82          68         119          98
NORTH PLATTE PROJ         59          94          60          99          63

To March 2001 Basin Outlook Report Contents Page