PROVISIONAL DATA SUBJECT TO REVISION

LOCATION.--Lat 39°16'55", long 77°47'22", NAD 27, Jefferson County, 
        Hydrologic Unit 02070007, on left bank 0.4 mi downstream from 
        Cattail Run, 1.0 mi upstream from Millville, 5.0 mi upstream 
        from Harpers Ferry, and at mile 4.7.
DRAINAGE AREA.--3,041 mi2.
PERIOD OF RECORD.--April 1895 to March 1909, August 1928 to September 
        2001 (measurements, daily mean discharges, and annual maximums); 
        October 2001 to September 2004 (measurements, daily mean 
        discharges, annual maximums, and discharges at one hour or less 
        intervals); October 2004 to current year (measurements, daily 
        mean discharges, annual maximums, and gage heights and 
        discharges at one hour or less intervals).
REVISED RECORDS.--WSP 951: 1936(M). WSP 1432: 1895-99, 1901-02, 1905, 
        1907-08, 1932(M), 1935(M).
GAGE.--Water-stage recorder with satellite telemeter. Datum of gage is 
        293.00 ft above NGVD 29. Apr. 15, 1895, to Mar. 31, 1909, 
        nonrecording gage at site 0.8 mi downstream atdatum 0.32 ft 
        higher. 
REMARKS.--Some regulation by upstream hydroelectric plants, including 
        that of Potomac Light and Power Company, 0.5 mi upstream from 
        station.
EXTREMES OUTSIDE PERIOD OF RECORD.--Flood of 1870 reached practically 
        same stage as flood of Mar. 18, 1936, 26.36 ft, discharge, 
        151,000 ft3/s.

This gaging station is maintained in cooperation with:
        Allegheny Energy Supply Company