SURFACE-WATER RECORDS
LOCATION.--Lat 40°38'11", long 74°27'05" referenced to North American Datum of 1983, Watchung Borough, Somerset County, NJ, Hydrologic Unit 02030105, on right bank at Watchung Borough Administration Building in Watchung, 150 ft downstream from bridge on Mountain Boulevard, 400 ft downstream from East Branch Stony Brook, and 2.9 mi upstream from confluence with Green Brook.
DRAINAGE AREA.--5.51 mi².
PERIOD OF RECORD.--Continuous-record discharge station October 1974 to current year.
REVISED RECORDS.--WDR NJ-86-1: 1973 (P).
GAGE.--Water-stage and precipitation recorder with telemetry and crest-stage gage. Datum of gage is 162.24 ft above NGVD of 1929. Prior to Oct 1, 1996, at datum 10.00 ft higher.
REMARKS.--Records fair, except estimated discharges, which are poor. Occasional regulation from Watchung and Best Lakes directly upstream from station and other small lakes. Discharges above 500 ft³/s from rating curve extended on basis of step-backwater computation of peak flow. Channel significantly enlarged and modified in 1991, and modified again in 1997 when the right wall was replaced.
EXTREMES FOR PERIOD OF RECORD.--Maximum discharge, 5,380 ft³/s, Sep 16, 1999, gage height, 17.16 ft, from rating curve extended above 500 ft³/s on basis of step-backwater computation of peak flow; maximum gage height, 20.40 ft, Jul 14, 1975, adjusted to current datum; minimum discharge, 0.00 ft³/s, Sep 13, 1982.
EXTREMES OUTSIDE PERIOD OF RECORD.--Flood of Aug 2, 1973 reached a stage of 24.5 ft (from floodmark; adjusted to current datum), discharge, 10,500 ft³/s (highest since 1896; from slope-area measurements of peak flow).

Peak Flood Chart

National Weather Service flood stage for this gage is 14 ft.

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