Continuous water-quality measurements are collected seasonally (May 1 through November 30).

Available data

Select data types to graph from categories based on the way the data were collected.

10 data types available - data from 1981-10-01 to 2026-08-09

7 data types available - data from 1921-08-04 to 2026-08-08

2 data types available - data from 1966-10-20 to 2026-05-15

508 Observed properties (data types) available - with data from 1923-08-12 to 2026-06-16

431 Sampling activities

2 data types available - with data from 1921-08-08 to 2022-04-08

7 data types available - data from 1921-08-04 to 2026-08-08

Available location images

Millstone River at Blackwells Mills

Millstone River at Blackwells Mills, NJ

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Metadata Element	Location Metadata	Metadata Code
Agency	U.S. Geological Survey	USGS
Location identification number	01402000	n/a
Location name	Millstone River at Blackwells Mills NJ	n/a
Site type	Stream	ST
Decimal latitude (WGS84)	40.475	n/a
Decimal longitude (WGS84)	-74.5758333333333	n/a
Latitude-longitude method	Interpolated from map	M
Latitude-longitude accuracy	Accurate to + or - 1 sec.	S
District	New Jersey	34
State	New Jersey	34
County	Somerset County	035
Country	United States of America	n/a
Altitude of gage/land surface	25.93 feet	n/a
Method altitude determined	GNSS2 - Level 2 Quality Survey Grade Global Navigation Satellite System	X
Altitude accuracy	0.05 feet	n/a
Altitude datum	North American Vertical Datum of 1988	NAVD88
Subbasin hydrologic unit	Raritan	02030105
Drainage basin		n/a
Date of first construction		n/a
Drainage area	258 square miles	n/a
Contributing drainage area		n/a
Time zone abbreviation	EST	n/a
Site honors Daylight Saving Time	Y	n/a
National aquifer		n/a
Local aquifer		n/a
Local aquifer type		n/a
Well depth		n/a
Hole depth		n/a
Source of depth data		n/a