Date: May 1, 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.
Storage at three out of six major hydroelectric reservoirs in Montana was in the normal range, one was above normal, and two were below normal. Storage for April was normal at Canyon Ferry Lake, Bighorn Lake, and Hungry Horse Reservoir. Storage was above normal in Lake Koocanusa and below normal in Fort Peck and Flathead Lakes.
For the month of April, water storage remained below normal at four major irrigation reservoirs: Lima, Clark Canyon, Gibson, and Fresno Reservoirs.
The following summary lists preliminary streamflow and reservoir data and long-term-average values for purposes of comparison.
| Station | March monthly mean discharge, in ft3/s | 1971-2000 Average discharge, in ft3/s | Percent of average |
|---|---|---|---|
Yaak River near Troy |
581 |
1,960 |
30 |
Blackfoot River near Bonner |
876 |
2,140 |
41 |
Clark Fork at St. Regis |
4,410 |
9,000 |
4.9 |
Middle Fork Flathead River nr West Glacier |
1,120 |
3,300 |
34 |
Marias River near Shelby |
330 |
1,000 |
33 |
Rock Creek below Horse Creek, nr Int'l
Bndry |
5.75 |
75 |
7.6 |
Yellowstone River at Corwin Springs |
1,160 |
1,730 |
67 |
Yellowstone River at Billings |
2,400 |
4,440 |
54 |
|
Hydroelectric reservoirs |
March contents in acre-feet | Percent of capacity | Percent of 1971-2000 average |
|---|---|---|---|
Canyon Ferry Lake |
1,432,000 |
72 |
97 |
Fort Peck Lake |
8,811,000 |
47 |
57 |
Bighorn Lake |
779,600 |
57 |
98 |
Lake Koocanusa |
3,227,000 |
56 |
137 |
Hungry Horse reservoir |
2,184,000 |
63 |
112 |
Flathead Lake |
671,800 |
38 |
72 |
|
|||
Lima Reservoir |
30,350 |
36 |
53 |
Clark Canyon Reservoir |
122,700 |
48 |
76 |
Gibson Reservoir |
22,740 |
24 |
37 |
Fresno Reservoir |
43,250 |
42 |
48 |