National Weather Service United States Department of Commerce

Missouri Basin River Forecast Center
Water Supply Statement
Issued in cooperation with the Natural
Resources Conservation Service
Issued:  August 10, 2007

 

Precipitation in the Missouri Basin was highly variable during July.
Most of the Montana received below average rain while Colorado and
Wyoming reported average to above average rainfall. Streamflow data
indicates the flows for July were below average.

Precipitation in Montana below average with amounts ranging from a trace
or less at Augusta, Cut Bank 34NW, and Sweetgrass, Montana; to 277
percent of  average (4.74 in.) Rapelje, Montana. Precipitation in
Wyoming was average to above average. Reports ranged from 19 percent of
average (0.19 in.) at Powell 23NW, Wyoming to 189 percent of average
(3.18 in.) at Riverton 1SW, Wyoming.  Precipitation in northeastern
Colorado was average, with reports ranging from 36 percent of average
(1.01 in.) at Burlington 4S  to 192  percent of average (4.40 in.) at
Lake George 8SW, Colorado.

Basin precipitation summaries for the Missouri Basin:

Basin               Average Precipitation
Milk St. Mary                15%
Milk Canada                   7%
Above Toston                 61%
Toston to Ft. Peck           43%
Lower Milk                   43%
Upper Yellowstone            82%
Wind River                  166%
Bighorn                     101%
Little Bighorn Tongue        67%
Powder                      107%
Lower Yellowstone            52%
Upper North Platte          100%
Lower North Platte           96%
North Platte Plains          86%
South Platte Mountains      103%
South Platte Plains         110%

 

 

 

July 2007 Basin Mean Precipitation


Stored water in the South Platte Basin as of August 1 was 91
percent of average for this time of the year. Stored water in the
North Platte Basin was 46 percent of average. Stored water in Boysen
Reservoir was 55 percent of the 30 year average. Buffalo Bill
Reservoir held 98 percent of average storage. Of the four
major irrigation reservoirs in Montana, Lima Reservoir had 47 percent
average storage; Clark Canyon was holding 50 percent of average water,
Gibson Reservoir had 19 percent of average stored water and Fresno
Reservoir had 103 percent of average stored water. Of the three major
hydroelectric reservoirs in Montana, Canyon Ferry and Fort Peck had
monthend storage in the average range; 95 and 56 percent of average water,
respectively. Bighorn lake was holding 97 percent of average
stored water.


Runoff during July, as indicated by U.S. Geological Survey longterm gaging stations,
was much below average. The Marias River near
Shelby, Montana had 18 percent of average runoff. The Yellowstone
River was estimated to have had 40 percent of average runoff at
Corwin Springs, while at Billings, Montana runoff was 28 percent of
average.


 
PRECIPITATION MAPS
July 2007  WY 2007
July 2007 Precipitation Percent of 1971-2000 Average WY2007 Precipitation as Percent of 1971-2000 Average
July 2007 Basin Mean Precipitation          WY2007 Basin Mean Precipitation
July 2007 MBRFC Basin Mean Precipitation      WY2007 MBRFC Basin Mean Precipitation