Flathead River

Last Updated: May 3, 2026

Total streamflow across the Flathead River was last observed at 53,840 cfs, and is expected to yield approximately 106,790 acre-ft of water today; about 96% of normal. Average streamflow for this time of year is 56,085 cfs, with recent peaks last observed on 2012-06-27 when daily discharge volume was observed at 165,650 cfs.

Maximum discharge along the river is currently at the Flathead River At Columbia Falls Mt reporting a streamflow rate of 19,000 cfs. However, the streamgauge with the highest stage along the river is the Flathead River At Perma Mt with a gauge stage of 11.38 ft. This river is monitored from 4 different streamgauging stations along the Flathead River, the highest being situated at an altitude of 3,983 ft, the Flathead River At Flathead British Columbia.

The Flathead River is a 158-mile-long river located in western Montana, USA.


15-Day Long Term Forecast


River Details

Last Updated 2026-05-03
Discharge Volume 106,790 ACRE-FT
Streamflow 53,840.0 cfs
Past 24 Hours: +2590.0 cfs (+5.05%)
Percent of Normal 96.0%
Maximum 165,650.0 cfs
2012-06-27
Seasonal Avg 56,085 cfs
       
River Streamflow Levels
Streamgauge Streamflow Gauge Stage 24hr Change (%) % Normal Minimum (cfs) Maximum (cfs) Air Temp Elevation
Flathead River At Flathead British Columbia
USGS 12355000
4440 cfs 8.2 ft 21.64
Flathead River At Columbia Falls Mt
USGS 12363000
19000 cfs 8.63 ft 10.47
Flathead River Near Polson Mt
USGS 12372000
15000 cfs 8.26 ft 0
Flathead River At Perma Mt
USGS 12388700
15400 cfs 11.38 ft 0
Seasonal Discharge Comparison
Maximum Streamflow Discharge
Streamflow Elevation Profile

The Flathead River (Salish: ntx̣ʷetkʷ, ntx̣ʷe ), in the northwestern part of the U.S. state of Montana, originates in the Canadian Rockies to the north of Glacier National Park and flows southwest into Flathead Lake, then after a journey of 158 miles (254 km), empties into the Clark Fork. The river is part of the Columbia River drainage basin, as the Clark Fork is a tributary of the Pend Oreille River, a Columbia River tributary. With a drainage basin extending over 8,795 square miles (22,780 km2) and an average discharge of 11,380 cubic feet per second (322 m3/s), the Flathead is the largest tributary of the Clark Fork and constitutes over half of its flow.