Perkiomen Creek at Graterford, Montgomery County PA (GRAP1)
Gage Location: Montgomery County, Pennsylvania	Site Location: Montgomery County, Pennsylvania
Latitude: 40.229	Longitude: -75.452	Elevation: 112.66 ft. MSL	Drainage Area: 279 Sq. Mi.
Minor Stage: 11 ft.	Moderate Stage: 13 ft.	Major Stage: 16 ft.
First Flood: 1915-01-07	Last Flood: 2013-01-31 Crest: 12.49 ft.	Datum change: 1927-09-14	Number of Floods: 81

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Year Before Datum Change	Number of Floods
1915	4
1916	0
1917	0
1918	2
1919	1
1920	0
1921	0
1922	0
1923	0
1924	0
1925	0
1926	0

Year After Datum Change	Number of Floods
1927	0
1928	1
1929	2
1930	0
1931	0
1932	0
1933	1
1934	1
1935	2
1936	1
1937	0
1938	1
1939	0
1940	2
1941	0
1942	1
1943	2
1944	0
1945	1
1946	2
1947	0
1948	1
1949	0
1950	1
1951	0
1952	4
1953	1
1954	0
1955	3
1956	0
1957	0
1958	1
1959	0
1960	1
1961	0
1962	0
1963	0
1964	0
1965	1
1966	0
1967	1
1968	1
1969	1
1970	1
1971	1
1972	2
1973	1
1974	0
1975	1
1976	0
1977	1
1978	1
1979	1
1980	0
1981	0
1982	1
1983	1
1984	1
1985	1
1986	0
1987	0
1988	0
1989	1
1990	1
1991	0
1992	0
1993	1
1994	0
1995	1
1996	2
1997	0
1998	0
1999	1
2000	2
2001	0
2002	1
2003	3
2004	3
2005	3
2006	1
2007	1
2008	2
2009	0
2010	1
2011	3
2012	0
2013	1

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