Antietam Creek near Sharpsburg, Washington County MD (SACM2)
Gage Location: Washington County, Maryland	Site Location: Washington County, Maryland
Latitude: 39.45	Longitude: -77.73	Elevation: 311.05 ft. MSL	Drainage Area: 281 Sq. Mi.
Minor Stage: 8 ft.	Moderate Stage: 10 ft.	Major Stage: 12 ft.
First Flood: 1928-07-11	Last Flood: 2012-10-31 Crest: 9.89 ft.	Datum change: 2011-03-16	Number of Floods: 31

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Height Above Flood Stage for Entire Period of Record Height Above FS Total Occurence Percent of Crest Occurrence Cumulative Total Flood Occurrence Percent of Floods above Listed Value 8 ft to 9 ft 7 22.6 8 ft or above 31 100.0 9 ft to 10 ft 9 29.0 9 ft or above 24 77.4 10 ft to 11 ft 7 22.6 10 ft or above 15 48.4 11 ft to 12 ft 4 12.9 11 ft or above 8 25.8 12 ft to 13 ft 0 0.0 12 ft or above 4 12.9 13 ft to 14 ft 1 3.2 13 ft or above 4 12.9 14 ft to 15 ft 2 6.5 14 ft or above 3 9.7 15 ft to 16 ft 0 0.0 15 ft or above 1 3.2 16 ft to 17 ft 1 3.2 16 ft or above 1 3.2

Height Above Flood Stage After Datum Change Height Above FS Total Occurence Percent of Crest Occurrence Cumulative Total Flood Occurrence Percent of Floods above Listed Value 8 ft to 9 ft 2 50.0 8 ft or above 4 100.0 9 ft to 10 ft 2 50.0 9 ft or above 2 50.0 10 ft to 11 ft 0 0.0 10 ft or above 0 0.0 11 ft to 12 ft 0 0.0 11 ft or above 0 0.0 12 ft to 13 ft 0 0.0 12 ft or above 0 0.0 13 ft to 14 ft 0 0.0 13 ft or above 0 0.0 14 ft to 15 ft 0 0.0 14 ft or above 0 0.0 15 ft to 16 ft 0 0.0 15 ft or above 0 0.0 16 ft to 17 ft 0 0.0 16 ft or above 0 0.0

Codes and description

C1|Crest information looks unreliable and incomplete and not used in frequency calculations. Some of the floods are based on current flood stage and nearby gage information.
C2|Crest information looks reliable despite potential problems. This data was used in frequency calculations.
C3|Crest height estimated by the USGS.
C4|Crest height is from the National Weather Service.
C5|Crest height affected by backwater.
C6|Crest occurred at a previous flood stage that is lower than the current flood stage. The crests below the new flood stage are not used in flood frequency calculations.
C7|Crest from USGS yearly peak and/or date is different than the crest we provide. In many cases MARFC uses crest based on backwater or ice effects.
C8|Crest month or day of occurrence has been estimated by The Middle Atlantic River Forecast Center usually based on nearby gage information.
C9|Crest date (day) in the month is unknown.
F1|Flow is an estimate.
F2|Flow affected by regulation or diversion and in some cases to an unknown degree.
F3|Flow effected by snow-melt, ice jam or debris jam break up.
F4|Flow affected by dam failure.
F5|Flow - All or part of the record affected by urbanization, mining, agricultural changes, channelization or other factors.
G1|Gage height at a different site and/or datum.
G2|Gage is not an official USGS gage with crests provided by the NWS. Crest information looks unreliable and incomplete and not used in flood frequency calculations.
G3|Gage datum changed during this year.
none,No code; Good Data

Updated: 08:09 AM Feb 08, 2013