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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Month Number of Floods After Datum Number of Floods Total Cumulative Total After Datum Cumulative Total January 8 10 8 10 February 4 7 12 17 March 6 6 18 23 April 5 5 23 28 May 4 4 27 32 June 5 5 32 37 July 8 9 40 46 August 5 6 45 52 September 12 12 57 64 October 6 6 63 70 November 5 5 68 75 December 6 6 74 81 Seasonal Totals Winter (Dec-Jan-Feb) 23 Spring (Mar-Apr-May) 15 Summer (Jun-Jul-Aug) 20 Fall (Sep-Oct-Nov) 23

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