Precipitation for March was generally much below average for the State. Year-to- date precipitation is below average for the State - the Belle Fourche drainage is still feeling the effects of the heavy snow last fall and is currently 99 percent of average. Reservoir levels vary from about 30 percent of average to 159 percent of average, the exception being Eden Reservoir which is too low to measure. Generally, the larger capacity reservoirs are above average storage. Forecast runoff varies from 20 to 77 percent of average. The mean of all the forecast points in the State is about 53 percent of average (47 percent below average).
Snowpack
SWE is below to much below average for the entire State. SWE in the
northwestern portion of the State is about 54 percent of average (63 percent of
last year). Northeast Wyoming SWE is currently about 73 percent of average (92
percent of last year). The southeast portion is currently about 75 percent of
average SWE (85 percent of last year). And the southwest is about 65 percent of
average (74 percent of last year).
Precipitation
March precipitation was much below normal over the State. Most of the basins in
the state received less than 70 percent of normal precipitation. The Wind River
and Lower North Platte received less than half of the usual precipitation. The
following table displays the major river basins and their departure from normal
for this month.
Basin | Departure from normal | Basin | Departure from normal |
Snake River | -39% | Upper North Platte River | -31% |
Yellowstone & Madison | -15% | Lower North Platte River | -55% |
Wind River | -57% | Little Snake River | -31% |
Bighorn | -29% | Upper Green River | -36% |
Shoshone & Clarks Fork | -26% | Lower Green River | -39% |
Powder & Tongue River | -31% | Upper Bear River | -35% |
Belle Fourche & Cheyenne | -21% |
Streams
Stream flow yield is expected to be below average across the State, and well
below average in the northern half of the State. Most probable yield for the
State is forecast to be about 52 percent of average (varies from 20 to 77 percent
of average). The northwest part of the State is expected to yield about 50
percent of normal -- yield estimates vary from 21 to 69 percent of normal through
the northwest region of the State. Yield from the northeast portion of Wyoming
will be below average (about 52 percent of average) -- yield estimates vary from
41 to 60 percent of average for the various forecast points. The southeast
portion of the state will be about 57 percent of normal -- yield estimates range
from 30 to 71 percent of normal. The southwest portion of Wyoming yield will be
much below normal (about 53 percent of average), and estimates vary from 20 to
77 percent of average.
Reservoirs
The following reservoir data is based on the usable capacity of each reservoir.
Although several reservoirs did not report, reservoir storage for those reporting
is generally near 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 MARCH 2001 BASIN AREA CURRENT AS LAST YR AS AVERAGE AS CURRENT AS CURRENT AS RESERVIOR % CAPACITY % CAPACITY % CAPACITY % AVERAGE % LAST YR -------------------------------------------------------------------------------- ALCOVA 85 85 88 97 100 ANGOSTURA 89 99 90 99 90 BELLE FOURCHE 99 101 73 135 98 BIG SANDY 20 55 52 39 36 BIGHORN LAKE 63 67 59 107 94 BOYSEN 75 88 89 84 85 BUFFALO BILL 55 67 56 100 82 BULL LAKE 41 63 55 75 65 DEERFIELD 99 99 89 112 101 EDEN NO REPORT ENNIS LAKE 73 71 81 90 102 FLAMING GORGE AVERAGE NOT ESTABLISHED FONTENELLE 32 30 46 70 105 GLENDO 78 92 83 94 85 GRASSY LAKE 85 84 74 115 102 GUERNSEY 41 41 47 86 100 HEBGEN LAKE 72 81 65 110 89 JACKSON LAKE 76 78 56 136 98 KEYHOLE 87 90 56 156 96 PACTOLA 99 98 85 116 100 PALISADES 55 85 72 76 65 PATHFINDER 76 98 61 125 77 PILOT BUTTE 74 71 68 108 104 SEMINOE 64 73 36 176 87 SHADEHILL 102 69 78 131 147 VIVA NAUGHTON RES 76 79 64 119 96 WHEATLAND #2 46 75 49 92 61 WOODRUFF NARROWS NO REPORT GLENDO PROJECT USERS 83 85 69 120 98 KENDRICK PROJECT 81 82 68 119 98 NORTH PLATTE PROJ 65 100 64 103 65