USGS Water-Year Summary for Site 01402000

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	Available Parameters
	00010 Temperature, water(Max.,Min.,Mean)
	00060 Discharge(Mean)
	00095 Specific cond at 25C(Max.,Min.,Mean)
	00300 Dissolved oxygen(Max.,Min.,Mean)
	00301 Diss oxygen,%saturtn(Max.,Min.,Mean)
	00400 pH(Max.,Min.,Med.)
	63680 Turbidity, Form Neph(Max.,Mean,Min.)

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Water year 2024: 2023-10-01 to 2024-09-30

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USGS Water-Year Summary 2024

01402000 MILLSTONE RIVER AT BLACKWELLS MILLS, NJ

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.

REVISIONS HISTORY - WSP 1552: 1924-25(M), 1926. WDR US-2011: 1999, 2007, 2010.

SURFACE-WATER RECORDS

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.

GAGE - Water-stage recorder with telemetry. Concrete control since Nov 18, 1933. Datum of gage is 25.93 ft above NAVD of 1988. 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.

WATER-QUALITY RECORDS

PERIOD OF RECORD -

DISCRETE DATA: Water years 1962-69, 1973, 1976-80, 1991 to current year.

CONTINUOUS DATA:

Water temperature, relative chlorophyll fluorescence, and relative phycocyanin fluorescence Jul 2020 to Sep 2021, Aug 2022 to Dec 2022, Apr 2023 to current year.

Specific conductance, pH, dissolved oxygen mg/L and percent saturation, and turbidity Aug 2022 to Dec 2022, Apr 2023 to current year.

REMARKS -

The accuracy of continuous water-quality data can be found here.

EXTREMES FOR PERIOD OF RECORD -

Maximum water temperature, 30.9 deg C, on Jul 16, 2024; minimum water temperature, 0.0 deg C, many days.

Maximum specific conductance, 558 uS/cm, many days; minimum specific conductance, 74 uS/cm, on Jul 15, 2023.

Maximum pH, 8.8 std units, many days; minimum pH, 6.5 std units, many days.

Maximum dissolved oxygen, 12.0 mg/l, on Aug 5, 2022; minimum dissolved oxygen, 2.5 mg/l, on May 27, 2024.

Maximum dissolved oxygen, 154% saturation, many days; minimum dissolved oxygen, 32% saturation, on May 27, 2024.

Maximum turbidity, 788 FNU on Jul 15, 2023; minimum turbidity, 2.0 FNU, on Nov 15, 2023.

Maximum chlorophyll, 75.95 RFU on Nov 12, 2020; minimum chlorophyll, 0.07 RFU many days.

Maximum phycocyanin, 47.58 RFU on Oct 29, 2020; minimum phycocyanin, 0.00 RFU, many days.