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Flatlick Branch at Chantilly

Highest listed crest 9.21 ftFlood stage 9.0 ft10 crests since 2008

The Flatlick Branch at Chantilly crested above flood stage 1 time among the 10 crests the National Weather Service lists from 2008 to 2021. The highest, 9.21 ft on September 8, 2011, was minor flooding, 0.21 feet above flood stage.

The gauge

Highest listed crest
9.21 ft
September 8, 2011
Flood stage
9.0 ft
Major flooding from 15.0 ft
Crests at major
0
1 above flood stage
Most recent flood crest
September 8, 2011
9.21 ft, minor flooding
Location
Fairfax County
Near Herndon (6.6 mi), Fairfax (7.4 mi), Manassas Park (7.8 mi)

Flood stages

The thresholds the National Weather Service uses for this gauge today, and how many listed crests reached each.

Flood categories, Flatlick Branch at Chantilly
Action stage6.09Sep 1, 2021The level at which the NWS or its partners begin to take action
Flood stage (minor)9.01Sep 8, 2011Minimal or no property damage, but possibly some public threat
Moderate flood stage10.00—Some inundation of structures and roads near the stream
Major flood stage15.00—Extensive inundation of structures and roads

Every listed crest

10 crests from 2008 to 2021. Filled: at or above flood stage. Hover a crest for its date and stage.

Listed crests at the Flatlick Branch at Chantilly, 2008 to 2021 6810121416ft Flood stage 9.0 ftMajor 15.0 ft May 11, 2008: 6.99 ft, action stage; 2,400 cubic feet per secondMay 26, 2009: 6.26 ft, action stage; 745 cubic feet per secondSep 8, 2011: 9.21 ft, minor floodingOct 13, 2011: 6.62 ft, action stage; 1,440 cubic feet per secondJul 12, 2013: 8.06 ft, action stage; 2,830 cubic feet per secondMay 1, 2014: 6.99 ft, action stage; 1,210 cubic feet per secondJul 8, 2015: 7.07 ft, action stage; 1,290 cubic feet per secondJul 21, 2018: 6.14 ft, action stage; 859 cubic feet per secondAug 15, 2019: 6.71 ft, action stage; 1,370 cubic feet per secondSep 1, 2021: 6.68 ft, action stage; 1,350 cubic feet per second Highest, 9.21 ft, Sep 8, 2011 201020152020

Crests at or above flood stage, by decade

Crests at or above flood stage per decade, Flatlick Branch at Chantilly 2000s: 0 2010s: 1 1 2020s: 0 2000s2010s2020s
  1. These are the crests the local National Weather Service office lists for the gauge: the highest on record and recent crests. Lesser floods between them may be missing, so counts by decade are a floor.
  2. Categories use today's flood stages. Levees, dams and channel changes since a crest can make old and new stages not directly comparable.

Highest crests

Highest listed crests, Flatlick Branch at Chantilly
1Sep 8, 20119.21+0.21Minor—
2Jul 12, 20138.06−0.94Action2,830
3Jul 8, 20157.07−1.93Action1,290
4May 11, 20086.99−2.01Action2,400
5May 1, 20146.99−2.01Action1,210
6Aug 15, 20196.71−2.29Action1,370
7Sep 1, 20216.68−2.32Action1,350
8Oct 13, 20116.62−2.38Action1,440
9May 26, 20096.26−2.74Action745
10Jul 21, 20186.14−2.86Action859

Other gauges in Fairfax County

Flood gauges in Fairfax County
Woodburn Road / Strathmeade Springs251.5258.68 ft, Jul 13, 20250
Annandale9.516.32 ft, Sep 8, 20113
Manassas Park12.020.20 ft, Jul 22, 20180
Huntington - Metro Bridge11.012.92 ft, Sep 9, 20110
McLean9.010.54 ft, Dec 25, 20220
Browns Mill Road / Wolf Trap195.0196.37 ft, Jul 13, 20250
Great Falls11.021.40 ft, Jun 22, 19721
Fairview Lake318.0318.47 ft, Sep 8, 20110
New Alexandria Storm Water Pumping Station - Downstream5.57.51 ft, Jul 8, 20191
New Alexandria Tide Gate5.56.19 ft, Oct 29, 20210

Fairfax County: every hazard · River floods across the country · Virginia

NOAA National Water Prediction Service, gauge CTYV2, retrieved October 30, 2026. Stages in feet on the gauge's own datum, not elevation. Crests are as the National Weather Service lists them; preliminary values may be revised.