Flathead Lake Private Harbor
Flathead Lake Private Harbor is a marina in Big Arm, Montana. The private marina provides 30-foot boat slips for purchase on a 99-year lease, with many including power.
Operator details
- Vessels
- Powerboat
Boat launches near Flathead Lake Private Harbor
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Typical flow by month
1939 to 2026
The water at Flathead Lake Private Harbor typically runs highest in June, at a median 24,700 cfs, and lowest in September, at 5,615 cfs. The highest flow on record for any single day is 72,700 cfs, in 1948.
| Month | Typical (cfs) | Usual range (cfs) | Relative level |
|---|---|---|---|
| January | 9,960 | 8,140 to 12,000 | |
| February | 8,970 | 6,900 to 11,900 | |
| March | 7,780 | 5,720 to 10,200 | |
| April | 8,790 | 6,270 to 13,500 | |
| May | 18,500 | 12,600 to 25,300 | |
| June | 24,700 | 15,600 to 36,150 | |
| July | 12,500 | 9,060 to 16,500 | |
| August | 5,700 | 4,270 to 7,620 | |
| September | 5,615 | 4,255 to 7,620 | |
| October | 7,020 | 4,710 to 9,080 | |
| November | 8,030 | 5,810 to 10,500 | |
| December | 9,760 | 7,720 to 12,100 |
Typical is the median of each month’s daily median values, and the usual range runs from the median 25th to the median 75th percentile, across about 87 years of record. Statistics published by the US Geological Survey for Flathead River near Polson MT (site 12372000). Conditions on any given day can fall well outside the usual range. Check the current reading before you go.
Current conditions
Streamflow
7,140 cfs
Normal (62nd)
Water level
5.42 ft
Water
63°F
High today
79°F
Wind
5 kt
Gusts 7 kt
Rain chance
8%
Week ahead
Forecast from Open-Meteo global models (NOAA & ECMWF). See full conditions →
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