Date: May 11, 2012
NOTES TO READER: e, estimated; 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. Percent of average for monthly mean discharge and
reservoir contents are based on the 30-year average, water years
1981-2010. The “normal” range is 80 to 120 percent of average.
Additional streamflow information is available at: http://mt.water.usgs.gov/.
Recent annual water data reports for the United States can be viewed at: http://wdr.water.usgs.gov/.
The USGS now offers a service where the user can receive updates about water conditions by subscribing to WaterAlert at: http://water.usgs.gov/wateralert.
Monthly mean streamflows were below normal at one of eight long-term U.S. Geological Survey gaging stations in Montana, normal at one gaging station, and above normal at six gaging stations for the month of April.
Monthly mean streamflows were below normal at Rock Creek below Horse Creek, near international boundary and normal at Marias River near Shelby.
Monthly mean streamflows were above normal at:
Contents were normal at four of six major hydroelectric reservoirs in Montana and above normal at two of six hydroelectric reservoirs. Contents were normal at Canyon Ferry, Fort Peck, Bighorn, and Lake Koocanusa. Contents were above normal at Hungry Horse Reservoir and Flathead Lake.
Contents were normal at one and above normal at three major irrigation reservoirs in Montana. Contents were normal at Gibson Reservoir, whereas contents were above normal at Lima, Clark Canyon, and Fresno Reservoirs.
April 2012 streamflow and reservoir contents data and long-term-average values are summarized for purposes of comparison. Data in this news release are preliminary. Final data will be provided in the annual report (WDR-US-2012), Water-resources data for the United States when it becomes available in April 2013.
| Station | Monthly mean discharge, in ft3/s | Average discharge, in ft3/s | Percent of average |
|---|---|---|---|
Yaak River near Troy |
3,070 |
1,870 |
164 |
Blackfoot River near Bonner |
4,660 |
2,060 |
226 |
Clark Fork at St. Regis |
17,620 |
9,240 |
191 |
Middle Fork Flathead River near West Glacier |
6,610 |
3,210 |
206 |
Marias River near Shelby |
1,130 |
1,100 |
103 |
|
Rock Creek below Horse Creek, near international
boundary |
14.4 |
93.8 |
15 |
Yellowstone River at Corwin Springs |
3,190 |
1,560 |
204 |
Yellowstone River at Billings |
5,880 |
4,080 |
144 |
|
Hydroelectric reservoirs |
Contents in acre-feet | Percent of capacity | Percent of average |
|---|---|---|---|
Canyon Ferry Lake |
1,610,000 |
81 |
109 |
Fort Peck Lake |
15,370,000 |
81 |
114 |
Bighorn Lake |
824,300 |
61 |
107 |
Lake Koocanusa |
3,047,000 |
53 |
117 |
Hungry Horse reservoir |
2,805,000 |
81 |
128 |
Flathead Lake |
1,303,000 |
73 |
134 |
Irrigation reservoirs |
Contents in acre-feet |
Percent of capacity |
Percent of average |
|---|---|---|---|
Lima Reservoir |
77,220 |
92 |
143 |
Clark Canyon Reservoir |
175,700 |
69 |
124 |
Gibson Reservoir |
73,130 |
76 |
117 |
Fresno Reservoir |
94,450 |
92 |
126 |
* 30-year average based on 1981-2010 data.