USGS Water-Year Summary for Site 01184000

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	Available Parameters
	00060 Discharge(Mean)
	00065 Gage height(Mean)

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

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USGS Water-Year Summary 2024

01184000 CONNECTICUT RIVER AT THOMPSONVILLE, CT

LOCATION - Lat 41°59'14", long 72°36'21" referenced to North American Datum of 1927, Hartford County, CT, Hydrologic Unit 01080205, on right bank just upstream from Enfield Dam, 1.0 mi downstream from Thompsonville, 3.0 mi downstream from Massachusetts-Connecticut State line, and at mile 63.6.

DRAINAGE AREA - 9,660 mi².

REVISIONS HISTORY - WSP 741: 1932. WSP 891: Drainage area. WDR CT-77-1: 1976. WDR CT-83-1: Drainage area, 1982.

SURFACE-WATER RECORDS

PERIOD OF RECORD - July 1928 to current year.

GAGE - Water-stage recorder and crest-stage gage. Telephone telemetry at station. Satellite telemetry at station. Adjustments to datum of gage, referenced to National Geodetic Vertical Datum of 1929 (NGVD29), are listed in the following table; to convert the gage height record for the time periods listed below, apply the following conversions in order to determine elevation in NGVD29 or North American Vertical Datum of 1988 (NAVD88):

        Time Period              To NGVD29, in ft            To NAVD88, in ft      
Jul. 5, 1928 - Apr. 12, 1983          +38.48                      +37.75
Apr. 13, 1983 - Feb. 29, 1984         +28.48                      +27.75
Mar. 1, 1984 - Nov. 28, 1986          +37.48                      +36.75
Nov. 28, 1986 - present               +28.48                      +27.75

Additionally, the annual water year peak gage heights published on the USGS National Water Information System (NWIS) peak streamflow website (http://nwis.waterdata.usgs.gov/ct/nwis/peak/?site_no=01184000&agency_cd=USGS) have been adjusted to the datum in use for each of the periods listed in the table below:

        Time Period                      Gage height change, in ft                      
Jul. 5, 1928 - Apr. 12, 1983                    No change                                    
Apr. 13, 1983 - Feb. 29, 1984                    +10.00
Mar. 1, 1984 - Nov. 28, 1986                      +1.00
Nov. 28, 1986 - Sep. 30, 2016                    +10.00
Oct. 1, 2016 - present                          No change

REMARKS -

Flow regulated by power plants, by diversion from Chicopee River Basin and by First Connecticut and Second Connecticut Lakes, Lake Francis, Moore and Comerford Reservoirs, Quabbin Reservoir, and other reservoirs, combined usable capacity, about 107 billion ft³.

Water Year 2020-2022: Records good except for periods of estimated discharges, which are poor.
Water Year 2019: Records good except for periods of estimated discharges, which are fair.
Water Year 2018: Records good except for periods of estimated discharges, which are poor.
Water Year 2017: Records good except for periods of estimated discharges, which are fair.
Water Year 2014-2016: Records good except for periods of estimated daily discharges, which are fair.

EXTREMES FOR PERIOD OF RECORD - Maximum peak stage of 16.60 ft. on Mar. 20, 1936 is from flood marks and is referenced to datum at that time; Minimum instantaneous discharge, 968 ft³/s, Oct. 20, 1963.

WATER-QUALITY RECORDS

PERIOD OF RECORD - Water years 1956, 1966 to current year.

PERIOD OF DAILY RECORD -

WATER TEMPERATURE: October 1955 to September 1956, October 1973 to September 1999, December 2001 to August 2004, October 2019 to current year.
SPECIFIC CONDUCTANCE: October 1974 to September 1999, December 2001 to August 2004, October 2019 to current year.
pH: October 2019 to current year.
DISSOLVED OXYGEN: October 2019 to current year.
TURBIDITY: October 2019 to current year.
fDOM: October 2019 to current year.
NITRATE: October 2019 to current year.

INSTRUMENTATION - Water-quality monitor October 1973 to August 2004. August 2019 to current year. Independent Nitrate sensor January 2020 to current year.

EXTREMES FOR PERIOD OF DAILY RECORD -

--WATER TEMPERATURE: Maximum, 30.3°C on Jul. 28, 2020; minimum, -0.10°C on multiple dates.
--SPECIFIC CONDUCTANCE: Maximum, 314 µS/cm Feb. 16, 2021; minimum 60 µS/cm Jul. 19, 2021.
--DISSOLVED OXYGEN: Maximum, 15.5 mg/L Dec. 21, 2019; minimum, 3.6 mg/L Sep. 29, 2021.
--pH: Maximum, 9.3 units Sep. 24, 2020, minimum; 6.6 units Jul. 19, 2021.
--TURBIDITY: Maximum, xxx FNU Nov. 15, 2020; minimum, x.x FNU multiple dates.
--NITRATE: Maximum, 0.75, Dec. 25, 2020; minimum, 0.23, Mar. 31, 2020.