TidalMapFlatlick Branch above Frog Branch at Chantilly, VA Water Level Today
NWS river forecast
| When | Stage | Flow |
|---|
Forecast from the NOAA National Water Prediction Service. Issued a few times a day and only while a forecast is active. Not for navigation.
Last 30 days
About this gauge
USGS gauge 01656903 sits on Flatlick Branch and reads everything draining 4.2 square miles of the Middle Potomac-Anacostia-Occoquan basin. Its datum sits 257 feet above sea level NAVD88. Daily flow has been on record here since 2007, 19 years of it.
Where this gauge sits in the drainage
No gauged site sits above this one on the mainstem, so this is the first published reading on the river. Downstream the next reading comes from Bull Run above Occoquan Reservoir near Clifton, VA at 190 square miles, so what passes this gauge is about 2% of the water measured there.
Normal flows here
Flatlick Branch runs a median of 2.7 cfs at this gauge across 19 years of record. February is the fullest month at a median 4.1 cfs, and September the leanest at 0.9 cfs. The highest daily mean on record is 730 cfs in 2011, and the lowest is 0.1 cfs in 2007.
| Month | Median flow | Share of annual median |
|---|---|---|
| Jan | 3.4 cfs | 128% |
| Feb | 4.1 cfs | 155% |
| Mar | 3.9 cfs | 147% |
| Apr | 3.2 cfs | 119% |
| May | 3.9 cfs | 147% |
| Jun | 2.3 cfs | 87% |
| Jul | 1.7 cfs | 64% |
| Aug | 1.2 cfs | 45% |
| Sep | 0.9 cfs | 33% |
| Oct | 1.6 cfs | 60% |
| Nov | 1.8 cfs | 68% |
| Dec | 3.2 cfs | 121% |
Medians from the USGS daily-statistics record, 2007 to 2026. A month at 100% is running at its own long-term median.
Flood stages and record crests
Flatlick Branch reaches flood stage at this gauge at 9 feet. NWS starts watching it at 6 feet. The highest crest on record is 9.2 feet, in September 2011.
| Category | Gage height |
|---|---|
| Action | 6 ft |
| Minor flooding | 9 ft |
| Moderate flooding | 10 ft |
| Major flooding | 15 ft |
| When | Crest |
|---|---|
| September 2011 | 9.2 ft |
| July 2013 | 8.1 ft |
| July 2015 | 7.1 ft |
| May 2008 | 7 ft |
| May 2014 | 7 ft |
Flood categories and crest history from the NOAA National Water Prediction Service, gauge CTYV2. Stages are gage height, not depth. Not for navigation.
Nearby river gauges
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- Difficult Run above Fox Lake near Fairfax, VA
- Snakeden Branch above Lake Audubon at Reston, VA
- Broad Run near Leesburg, VA
- Long Branch at Olley Lane near Fairfax, VA
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- Difficult Run near Great Falls, VA
- Accotink Creek near Annandale, VA
- Potomac River at Edwards Ferry near Poolesville,md
- Accotink Creek at Keene Mill Rd at Springfield, VA
- Tripps Run at Falls Church, VA
Live streamflow and gage height: USGS gauge 01656903. Percentile context computed against the gauge's period of record. Not for navigation.
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