Data were downloaded from USGS web site:
http://waterdata.usgs.gov/ma/nwis/uv?dd_cd=01&dd_cd=03&dd_cd=19&format=g...

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LOCATION--Lat 42°39’35", long 70°53’39", Essex County, Hydrologic Unit 01090001, on left bank 200 ft downstream from Willowdale Dam, 1.5 mi downstream from Howlett Brook, and 4 mi upstream from Ipswich.
DRAINAGE AREA--125 mi2.
PERIOD OF RECORD--Discharge: June 1930 to current year.Water-quality records: Water years 1954, 1976–79.REVISED RECORDS--WSP 1621: 1930–58 (monthly runoff).
WDR MA-RI-84-1: drainage area.
GAGE--Data Collection Platform with satellite telemeter. Datum of gage is 20.63 ft above National Geodetic Vertical Datum of 1929.
REMARKS--Diversions upstream for municipal supply of Reading, Lynn, Peabody, Danvers, Salem, and Beverly. Occasional regulation by dams and reservoirs upstream.
COOPERATION BY--Massachusetts Department of Environmental Protection, Division of Watershed Management. Massachusetts Department of Conservation and Recreation
CALCULATIONS: Published data from USGS is in ft3 sec-1. We have converted this to m3 sec-1 by multiplying the data by the following conversion factor: 1ft3 = 0.0283168 m3