Missouri Basin River Forecast Center
Water Supply Statement
Issued in cooperation with the Natural
Resources Conservation Service
Issued:  June 13, 2006

Runoff for most  streams in the  Missouri  Basin are  forecast  to
be average to below average.  The high elevation snow pack in the
Missouri basin is generally below average for this time of the year,
at least in part due to an early melt season.  Precipitation in the
Missouri basin was at the low end of average or below average
everywhere in the forecasted basins.   The Wind River Basin was the
extreme with 21 percent of average precipitation.


Upper Missouri Basin

The high elevation snow pack in the Upper Missouri Basin as of
June 1 was below average.  The snow pack above Toston,  Montana
was 65 percent of average.  The snow pack between Toston and Fort
Peck, Montana was 42 percent.  The snow pack in the St Mary and
Milk river basins was 91 percent.

May precipitation above Toston was below average with 51 percent of
normal. From Toston to Ft. Peck precipitation was below average at 83
percent of normal.  The St. Mary and Milk river basins were also below
normal with 74 and 80 percent of normal precipitation, respectively.


May 2006 Upper Missouri Mean Precip                     Oct-May WY2006 Upper Missouri Mean Precip

The St. Mary River is forecast to have 83 percent of average June-
September flows.  Runoff is expected to range around 105 percent of
average for the Missouri Basin above Fort Peck, Montana.  Forecasts
for the Milk River Basin call for 83 to 107 percent of average
runoff.

Of the four major irrigation reservoirs in Montana:  Lima Reservoir
had 118 percent average storage, Clark Canyon was holding 68 percent of
average water, Gibson Reservoir had 108 percent of average stored
water, and Fresno Reservoir had 95 percent of average stored water.
The  major  hydroelectric  reservoirs  in  Montana (Canyon  Ferry and Fort
Peck) had monthend storage in the average to  below average range; 94 and
63 percent of average water, respectively.

As indicated by the U.S. Geological Survey long term gaging stations,
the Marias River near Shelby, Montana had an estimated 82 percent
of average runoff in May. 

Yellowstone Basin

The high elevation snow pack in the Yellowstone Basin was mostly
below average on June 1.  The snow pack in the Upper Yellowstone
Basin was 53 percent of average. The snow packs in the Wind,
Bighorn, and Shoshone Basins were 24, 20, and 31 percent of
average, respectively.  There were no remaining snow packs in either
the Tongue or Powder basins, making both basins below average.

Precipitation during the month of May was about 21 percent of
average in the Wind River Basin above Boysen Reservoir, 53 percent
of average in the Upper Yellowstone Basin, 61 and 65 percent of
average in the Bighorn and Little Bighorn Basins, respectively,
84 percent of average in the Powder-Tongue basins, and 71 percent
of average in the lower Yellowstone Basin.



Stream flow in the Yellowstone Basin is forecast to be mostly
below average during the upcoming spring and summer.  Runoff at
Billings, Montana is expected to be 79 percent of average, with
a probable range between 64 and 93 percent of average.  Stream
flow for the Wind-Bighorn Basin above St. Xavier, Montana is
forecast to be 44 to 52 percent of average with a probable range
of 10 to 94 percent of average flow in sub-basins.  Flow in the
Tongue Basin is expected to be 50 to 65 percent of average with
a reasonably likely range of 10 to 94 percent of average flow.
Flows in the Powder River are expected to be about 51 to 52
percent of average with a reasonably likely range of 5 to 105
percent.

Monthend storage was at 90 percent of average at Boysen Reservoir
in Wyoming, 141 percent of average at Buffalo Bill Reservoir in
Wyoming, and 92 percent of average at Bighorn Reservoir on the
Wyoming/Montana border.

Runoff during May in the Yellowstone River was 154 percent
of the 1971 to 2000 average at Corwin Springs, Montana and 118
percent of that average at Billings, Montana.
(http:/mt.water.usgs.gov/pub/nwc.release.html)
 

Platte Basin

The high elevation  snow pack in the Upper North Platte Basin was
48 percent of average on June 1.  The snow pack in the North Platte
Basin below Seminoe  Reservoir was 1 percent of average. The snow
pack in the South Platte Basin was 21 percent.

Precipitation, during May, in North Platte Basin above Seminoe
Reservoir was 43 percent average.  Precipitation in the  North
Platte Basin between Seminoe Reservoir and Guernsey Reservoir was
47 percent of average. The North Platte basin below Guernsey
Reservoir had 47 percent of average  precipitation.  The high
elevations of the South Platte Basin had 50 percent of average
precipitation whereas the plains had 39 percent of average
precipitation.
 

 
 
May 2006 Platte Mean Precip                         Oct-May WY2006 Platte Mean Precip
  


Stream flow in the Platte Basin are forecast to be below average
during the upcoming spring and summer.  Runoff for streams above
Seminoe Reservoir are expected to be between 60 and 80 percent of
average.  Stream flow for the North  Platte  below Seminoe
Reservoir  is forecast to be between 40 to 60 percent of average.
The South Platte Basin above South Platte, Colorado can expect about
60 to 70 percent of average  flow.  For the remainder of the South
Platte  Basin  flows are  expected to be between 60 and 80  percent
of  average.

Stored  water in the North  Platte  Basin as of June 1 was 66 percent
of average.  The South  Platte  Basin had 70  percent of average
stored water.


              Precipitation Maps
 
          May 2006            Oct-May WY 2006

                          

May 2006 Precipitation Percent of 1971-2000 Average  Oct-May  WY2006 Precipitation as Percent of 1971-2000 Average


May 2006 Basin Mean Precipitation                    Oct-May WY2006 Basin Mean Precipitation

                               

May 2006 MBRFC Basin Mean Precipitation              Oct-May WY2006 MBRFC Basin Mean Precipitation

 


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