Date: November 4, 2009

Data in this release are preliminary. Final data will be provided in the annual report (WDR-US-2009), Water-resources data for the United States.

NOTES TO EDITOR: (1) ft3/s is an abbreviation for cubic feet per second which is the rate of discharge representing a volume of a cubic foot of water passing a given point during one second and is equivalent to 7.48 gallons per second or 448.8 gallons per minute. (2) the "normal" range is 80 to 120 percent of average.

OCTOBER STREAMFLOWS VARY RESERVOIR STORAGE MOSTLY NORMAL

At eight long-term U.S. Geological Survey gaging stations, the monthly mean streamflows for the month of October were normal at four and below normal at four. Monthly mean streamflows were normal at:

Contents of reservoirs at five out of six major hydroelectric reservoirs in Montana remained normal: Canyon Ferry Lake, Bighorn Lake, Lake Koocanusa, Hungry Horse Reservoir, and Flathead Lake. Contents were below normal in Fort Peck Lake.

For the month of October, contents at at two major irrigation reservoirs was normal: Lima and Clark Canyon Reservoirs. Contents were below normal in Gibson and Fresno Reservoirs.

Untitled Document
Station October monthly mean discharge, in ft3/s 1971-2000 Average discharge, in ft3/s Percent of average
Yaak River near Troy
110
178
62
Blackfoot River near Bonner
543
634
86
Clark Fork at St. Regis
3,040
3,340
91
Middle Fork Flathead River near West Glacier
472
950
50
Marias River near Shelby
246
361
68
Rock Creek below Horse Creek, near International Boundary
1.05
1.94
54
Yellowstone River at Corwin Springs
1,440
1,540
94
Yellowstone River at Billings
4,220
4,400
96

e, estimated.

Hydroelectric reservoirs

 October contents in acre-feet Percent of capacity Percent of 1971-2000 average
Canyon Ferry Lake
1,717,000
86
100
Fort Peck Lake
12,920,000
68
79
Bighorn Lake
1,048,000
77
103
Lake Koocanusa
4,922,000
86
111
Hungry Horse reservoir
3,075,000
89
114
Flathead Lake
1,548,000
86
97

Irrigation reservoirs
Lima Reservoir
32,680
39
112
Clark Canyon Reservoir
145,700
57
116
Gibson Reservoir
13,840
14
39
Fresno Reservoir
41,710
40
77