Warning: Javascript must be enabled to use all the features on this page!

Page Loading - Please Wait...

Click to hideNews Bulletins
Click to hide state-specific text


USGS 01402000 Millstone River at Blackwells Mills NJ


Click to hidestation-specific text
During winter months, cold and ice may result in inaccurate real-time gage height and streamflow data. Adjustments or deletions of this data can only be done after detailed analysis.



LOCATION.--Lat 40°28'30", long 74°34'33" referenced to North American Datum of 1983, Hillsborough Township, Somerset County, NJ, Hydrologic Unit 02030105, on left bank 30 ft downstream from highway bridge on Blackwells Mills Causeway at Blackwells Mills, 0.3 mi downstream from Six Mile Run, and 2.0 mi south of Borough of Millstone.
DRAINAGE AREA.--258 mi2.
PERIOD OF RECORD.--June 1903 to December 1904 (gage heights only), August 1921 to current year. Monthly discharge only for some periods, published in WSP 1302. Published as "at Millstone" 1903-04.
REVISED RECORDS.--WSP 1552: 1924-25(M), 1926. WDR US-2011: 1999, 2007, 2010.
GAGE.--Water-stage recorder with telemetry. Concrete control since Nov 18, 1933. Datum of gage is 26.97 ft above NGVD of 1929. June 27, 1903 to Dec 31, 1904, non-recording gage at bridge 2.0 mi downstream at Millstone at different datum. Aug 4, 1921 to Aug 16, 1928, non-recording gage at present site and datum.
REMARKS.--Records good, except for estimated discharges and discharges greater than 2,000 ft3/s, which are fair. Inflow from and losses to Delaware and Raritan Canal upstream of station. Flow slightly regulated by Carnegie Lake, capacity, 310,000,000 gal and several smaller reservoirs, combined capacity, 49,800,000 gal.
EXTREMES FOR PERIOD OF RECORD.--Maximum discharge, 22,200 ft3/s, Aug 28, 1971, gage height, 18.68 ft, from high-water mark, maximum gage height, 21.24 ft, Aug 28, 2011, maximum discharge occurred during different floodplain conditions; minimum discharge, 5.0 ft3/s, Sep 16, 1923.


PERIOD OF RECORD.--Water years 1962-69, 1973, 1976-80, 1991 to current year.
REMARKS.--Discrete water-quality data were collected as part of the New Jersey Ambient Surface-Water-Quality Monitoring Network.

Peak Flood Chart

Gage Photo

National Weather Service flood stage for this gage is 9.0 ft.

Forecasts for this gage are issued by the National Weather Service routinely year-round.
Forecast information is available here.

This station managed by the New Jersey Water Science Center.

Available Parameters Available Period
All 2 Available Parameters for this site
00060 Discharge 1981-10-01  2018-02-23
00065 Gage height, H350XL Bubbler 2014-10-01  2018-02-23

Graph w/ stats
Graph w/o stats
Graph w/ (up to 3) parms
Days  (7)

  -- or --
Begin date

End date

Summary of all available data for this site
Instantaneous-data availability statement

Discharge, cubic feet per second

Most recent instantaneous value: 572 02-23-2018   08:15 EST
Graph of  Discharge, cubic feet per second

Add up to 2 more sites and replot for "Discharge, cubic feet per second"

 Add site numbers

Create presentation-quality / stand-alone graph.   Subscribe to WaterAlert      

Daily discharge, cubic feet per second -- statistics for Feb 23 based on 96 years of record more
Median Most Recent
Value Feb 23
Mean 75th
86.9 264 378 572 658 723 3490

Gage height, feet, H350XL Bubbler

Most recent instantaneous value: 2.68 02-23-2018   08:15 EST
Graph of  Gage height, feet

Add up to 2 more sites and replot for "Gage height, feet, H350XL Bubbler"

 Add site numbers

Create presentation-quality / stand-alone graph.   Subscribe to WaterAlert