Date: November 4, 2008
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.
At eight long-term U.S. Geological Survey gaging stations, the monthly mean streamflows for the month of October were normal at five and below normal at three. The monthly mean streamflows at the following stations were normal:
Water storage remained in the normal range at five out of six major hydroelectric reservoirs in Montana: Canyon Ferry Lake, Bighorn Lake, Lake Koocanusa, Hungry Horse Reservoir, and Flathead Lake. Storage remained below normal in Fort Peck Lake.
For the month of October, water storage at four major irrigation reservoirs was normal at three and below normal at one. Storage at Lima, Gibson, and Fresno Reservoirs was normal; Clark Canyon Reservoir remained below normal.
Streamflow and reservoir data and long-term-averages are summarized for purposes of comparison.
Station | October monthly mean discharge, in ft3/s | 1971-2000 Average discharge, in ft3/s | Percent of average |
---|---|---|---|
Yaak River near Troy |
131 |
178 |
74 |
Blackfoot River near Bonner |
623 |
634 |
98 |
Clark Fork at St. Regis |
3,430 |
3,340 |
103 |
Middle Fork Flathead River near West Glacier |
694 |
950 |
73 |
Marias River near Shelby |
291 |
361 |
81 |
Rock Creek below Horse Creek, near International
Boundary |
1.16 |
1.94 |
60 |
Yellowstone River at Corwin Springs |
1,390 |
1,540 |
90 |
Yellowstone River at Billings |
4,130 |
4,400 |
94 |
Hydroelectric reservoirs |
October contents in acre-feet | Percent of capacity | Percent of 1971-2000 average |
---|---|---|---|
Canyon Ferry Lake |
1,462,000 |
73 |
85 |
Fort Peck Lake |
10,550,000 |
56 |
64 |
Bighorn Lake |
1,044,000 |
77 |
103 |
Lake Koocanusa |
4,942,000 |
86 |
112 |
Hungry Horse reservoir |
2,741,000 |
79 |
101 |
Flathead Lake |
1,537,000 |
86 |
96 |
|
|||
Lima Reservoir |
25,340 |
30 |
87 |
Clark Canyon Reservoir |
76,570 |
30 |
61 |
Gibson Reservoir |
29,010 |
30 |
82 |
Fresno Reservoir |
55,780 |
54 |
103 |