LOCATION--Lat 42° 38’03", long 71° 39’30", Middlesex County, Hydrologic Unit 01070004, on left bank 0.7 mi downstream from Trout Brook and 2.7 mi northwest of West Groton.
DRAINAGE AREA--63.7 mi², excludes 2.16 mi², above outlet of Ashby Reservoir.
PERIOD OF RECORD--Discharge: October 1949 to current year.
Water-quality records: Water year 1957.
REVISED RECORDS--WDR MA-RI-84-1: drainage area.
GAGE--Data Collection Platform with satellite telemeter. Datum of gage is 244.27 ft above National Geodetic Vertical Datum of 1929.
REMARKS--Occasional regulation at low flow by mill upstream; regulation greater prior to 1961. Entire flow from 2.16 mi² upstream from outlet of Ashby Reservoir diverted for municipal supply of Fitchburg except for occasional periods of spill.
COOPERATION BY-- Massachusetts Department Of Conservation and Recreation, Office of Water Resources.