USGS Water-Year Summary for Site 01194796

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	Available Parameters
	00010 Temperature, water(Max.,Min.,Mean)
	00010 Temperature, water(Max.,Min.,Mean)
	00065 Gage height(Max.,Min.,Mean)
	00095 Specific cond at 25C(Max.,Min.,Mean)
	00095 Specific cond at 25C(Max.,Min.,Mean)
	90860 Salinity, at 25C(Max.,Min.,Mean)
	90860 Salinity, at 25C(Max.,Min.,Mean)

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Water year 2024: 2024-10-01 to 2025-09-30

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USGS Water-Year Summary 2024

01194796 CONNECTICUT RIVER AT OLD LYME, CT

LOCATION - Lat 41°18'45", long 72°20'47" referenced to North American Datum of 1927, New London County, CT, Hydrologic Unit 01080205, on left bank at Connecticut Department of Energy and Environmental Protection Marine Headquarters boat dock gas house, 1,000 ft upstream from railroad bridge, near mouth of Connecticut River.

DRAINAGE AREA - 11,224 mi².

SURFACE-WATER RECORDS

PERIOD OF RECORD - June 1998 to current year.

GAGE - Water-stage recorder. Datum of gage is National Geodetic Vertical Datum of 1929. From February 1978 to June 1998, at site in jetty lighthouse at the mouth of the Connecticut River, at datum 4.56 ft below NGVD of 1929. Prior to Feb. 1978, at site at Lynde Point, at datum 9.68 ft below NGVD of 1929. Satellite telemetry at station.

REMARKS - Stage data in feet at 5-minute intervals available upon request.

EXTREMES FOR PERIOD OF RECORD - Maximum river elevation, 8.04 ft., Oct. 29, 2012; minimum tidal elevation, -2.85 ft., Mar. 2, 2021.

WATER-QUALITY RECORDS

PERIOD OF DAILY RECORD - SPECIFIC CONDUCTANCE: May 13, 2009 to current year. WATER TEMPERATURE: May 13, 2009 to current year. SALINITY: May 13, 2009 to current year.

INSTRUMENTATION - Water-quality monitors May 13, 2009 to current year. Two monitors at station, one is near the top of the river (called "TOP"), the other is near the bottom of the river (called "BOTTOM").

EXTREMES FOR PERIOD OF DAILY RECORD - WATER TEMPERATURE (top): Maximum, 29.1 °C, Jul. 22, 2011; minimum, -0.3 °C, Jan. 27, 2011. SPECIFIC CONDUCTANCE (top): Maximum, 48,300 microsiemens, Feb. 27, 2013; minimum, 77 microsiemens, May 2, 3, 2011. SALINITY (top): Maximum, 31 psu, on several days; minimum, 0 psu, on many days. WATER TEMPERATURE (bottom): Maximum, 29.0 °C, Jul. 20, 2013; minimum, -0.1 °C, on several days. SPECIFIC CONDUCTANCE (bottom): Maximum, 47,500 microsiemens, Dec. 16, 2012; minimum, 79 microsiemens, Mar. 26, 31, Apr. 2, 2010. SALINITY (bottom): Maximum, 31 psu, Dec. 16, 17, 2012, Jan. 11, Feb. 8, 27, 2013; minimum, 0 psu, on many days.