Potomac River at Point of Rocks, Frederick County MD (PORM2)
Gage Location: Frederick County, Maryland	Site Location: Frederick County, Maryland
Latitude: 39.274	Longitude: -77.543	Elevation: 200.63 ft. MSL	Drainage Area: 9651 Sq. Mi.
Minor Stage: 16 ft.	Moderate Stage: 20 ft.	Major Stage: 25 ft.
First Flood: 1889-06-02	Last Flood: 2012-10-31 Crest: 18.19 ft.	Datum change: 1929-10-28	Number of Floods: 114

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Date of Flood Crest(ft) Streamflow(cfs) Category Code 1889-06-02 40.2 460000 Major *** (5) 1896-10-01 27.2 204000 Major *** (5) 1898-08-12 18 127000 Minor *** (5) 1899-03-06 18.1 128000 Minor *** (5) 1901-04-22 22 161000 Moderate *** (5) 1902-03-02 29 219000 Major *** (5) 1903-03-01 16.6 110000 Minor *** (!!!) 1907-03-15 17.6 119000 Minor *** 1908-01-13 21.6 152000 Moderate *** 1910-06-18 23.5 168000 Moderate *** 1911-09-01 16.1 106000 Minor *** 1913-03-28 20 139000 Moderate *** 1915-06-04 20 139000 Moderate *** 1916-03-29 18.3 124000 Minor *** 1917-03-13 18.1 123000 Minor *** 1918-04-16 18.6 127000 Minor *** 1920-03-06 16.4 109000 Minor *** 1924-05-13 32.2 277000 Major *** 1928-05-02 21.3 145000 Moderate *** 1929-04-18 24.94 180000 Moderate *** 1929-10-23 17.4 110000 Minor *** 1932-05-14 23.34 158000 Moderate none 1933-04-21 19.3 123000 Minor none 1934-12-02 19.78 128000 Minor none 1936-02-28 18.13 113000 Minor none 1936-03-19 41.03 480000 Major none 1937-04-27 33.86 310000 Major none 1937-10-30 24.93 175000 Moderate none 1939-02-05 19.39 124000 Minor none 1942-05-24 21.13 125000 Moderate none 1942-10-16 40.43 418000 Major none 1942-12-31 20.47 126000 Moderate none 1945-09-20 21.98 139000 Moderate none 1948-04-15 16.04 87000 Minor none 1949-06-20 21.2 132000 Moderate none 1950-12-05 20.75 128000 Moderate none 1950-12-09 18.42 107000 Minor none 1951-06-15 17.52 99000 Minor none 1952-03-13 17.12 95800 Minor none 1952-04-29 20.67 127000 Moderate none 1952-11-23 19.68 118000 Minor none 1954-03-03 18.65 109000 Minor none 1954-10-17 21.02 130000 Moderate none 1955-08-20 29.08 214000 Major none 1960-04-01 17.35 97800 Minor none 1960-04-06 18.25 105000 Minor none 1960-05-10 20.28 124000 Moderate none 1961-02-21 17.9 102000 Minor none 1961-02-27 16.6 91800 Minor none 1962-03-23 19.45 116000 Minor none 1963-03-07 17.6 99800 Minor none 1963-03-21 20.47 125000 Moderate none 1964-03-06 16 87000 Minor none 1965-03-06 17.35 97800 Minor none 1967-03-08 22.53 144000 Moderate none 1970-04-03 16.64 92100 Minor none 1972-06-23 37.43 347000 Major none 1972-10-08 18.28 106000 Minor none 1973-04-29 16.58 91600 Minor none 1973-12-28 21.27 132000 Moderate none 1975-03-21 26.15 181000 Major none 1975-09-26 24.35 126000 Moderate none 1976-01-02 18.71 109000 Minor none 1976-10-11 27.25 193000 Major none 1978-01-28 21.22 132000 Moderate none 1978-03-16 22.01 139000 Moderate none 1978-03-28 18.43 107000 Minor none 1978-05-17 17.67 100000 Minor none 1979-01-25 17.29 96900 Minor none 1979-02-27 25.94 178000 Major none 1979-09-07 16.19 87800 Minor none 1982-06-15 16.66 92000 Minor none 1983-04-26 19.21 115000 Minor none 1984-02-16 28.14 199000 Major none 1984-03-30 20.8 128000 Moderate none 1984-04-06 19.49 117000 Minor none 1985-11-07 36.28 309000 Major none 1986-03-16 19.35 116000 Minor none 1987-04-18 23.49 153000 Moderate none 1988-05-20 17.01 96100 Minor none 1992-04-23 16.25 90000 Minor none 1993-03-06 24.94 167000 Moderate none 1993-03-25 18.12 105000 Minor none 1993-04-03 18.19 106000 Minor none 1993-04-18 20.17 123000 Moderate none 1993-11-29 19.25 115000 Minor none 1994-02-25 16.03 88200 Minor none 1994-03-11 17.78 102000 Minor none 1994-03-30 19 113000 Minor none 1996-01-21 36.34 310000 Major none 1996-01-28 16.53 92200 Minor none 1996-03-21 16.6 92800 Minor none 1996-09-08 36.26 309000 Major none 1997-11-09 17.37 99100 Minor none 1998-01-10 20.07 122000 Moderate none 1998-02-06 17.99 104000 Minor none 1998-02-19 18.23 106000 Minor none 1998-03-22 20.24 123000 Moderate none 2003-01-03 16.25 89970 Minor none 2003-02-24 16.5 91990 Minor none 2003-03-22 16.85 94820 Minor none 2003-09-21 23.12 150000 Moderate none 2003-12-12 19.58 18000 Minor none 2004-09-30 17.25 98100 Minor none 2005-03-30 19.37 116000 Minor none 2007-04-17 17 96000 Minor none 2008-05-13 16.99 96000 Minor none 2009-05-06 17.5 100000 Minor none 2010-01-26 21.42 134000 Moderate none 2010-03-15 25.52 172000 Major none 2011-03-12 19.92 121000 Minor none 2011-04-18 22.52 144000 Moderate none 2011-05-19 22.15 141000 Moderate none

MARFC Codes
Code Description
(!!!) Datum changed during this year.
(1) Backwater Effect.
(2) 15.77 ft also occurred on 11/25/1950 but only counted as one flood.
(3) Estimated from currrent USGS rating table.
(4) Estimated height from the USGS.
(5) Gage height at a different site and/or datum
(6) Discharge affected by Regulation or Diversion
(7) Due to changes, prior floods were based on present flood stage. Therefore, flood data could possibly be incomplete.
(8) Gage is a staff gage and not the offical USGS gage. Therefore, some floods may be missing from our study.
(9) Discharge effected by snow-melt, ice jam or debris jam break up
(A) Discharge affected to unknown degree by regulation or diversion.
(B) Month or day of occurrence is unknown or not exact.
(C) All or part of the record affected by urbanization, mining, agricultural changes, channelization, or other factors.
(D) Crest height adjusted to current datum.
(E) Estimated discharge.
(F) Only annual maximum peak available for this year.
(O) This flood occurred at a previous flood stage that is lower than the current flood stage. This is only a historical flood.
** Crest information looks reasonable despite potential problems. This data was used in our study.
*** Crest information looks unreliable and incomplete and was not used in our flood frequency study.
**** Gauge was discontinued in 2004. 2004 and later was not used in our study.
none No code

Updated: 08:58 AM Jun 28, 2012