SURFACE-WATER RECORDS
LOCATION.--Lat 40°35'06", long 74°30'28" referenced to North American Datum of 1983, Green Brook Township, Somerset County, NJ, Hydrologic Unit 02030105, on downstream right wingwall of bridge on Sebrings Mills Road (Greenbrook Road) at Middlesex, 0.4 mi downstream of mouth of Green Brook, and 2.3 mi upstream of mouth.
DRAINAGE AREA.--48.4 mi².
PERIOD OF RECORD.--Continuous-record discharge station June 1972 to September 1977, April 1996 to September 1998, February 2004 to September 2011 and February 2013 to current. Prior to October 1977, located on right bank, 107 ft upstream of bridge on Sebrings Mill Road, published as "Green Brook at Middlesex, NJ." Operated as an annual maximum gage water years 1992 to 1995, and 1999 to 2003.
REVISED RECORDS.--WDR US-2011: 1996(M), 1997(M), 1999(M), 2007(M), 2010(M).
GAGE.--Water-stage and precipitation recorder with telemetry and crest-stage gage. Datum of gage is 26.52 ft above NGVD of 1929. Continuous gage 1972-77 at site 130 ft upstream, datum at NGVD of 1929.
REMARKS.--Records good, except for estimated discharges, which are fair.
EXTREMES FOR PERIOD OF RECORD.--Maximum discharge 7,000 ft³/s, Aug 2, 1972, gage height, 41.18 ft, site and datum then in use; minimum discharge, 2.5 ft³/3, Jul 21, 1974.

WATER-QUALITY RECORDS
PERIOD OF RECORD.--Water years 1974, 1996-98, 2001-12.

Peak Flood Chart

National Weather Service flood stage for this gage is 9 ft.

Rain gage data is available from this location at this link.