USGS Water-Year Summary for Site 02246500

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	Available Parameters
	00010 Temperature, water(Max.,Min.,Mean)
	00060 Discharge(Mean)
	00065 Gage height(Mean,Tid.,Tid.)
	00095 Specific cond at 25C(Max.,Min.,Mean)
	00480 Salinity(Max.,Min.,Mean)
	63160 Stream level, NAVD88(Mean,Tid.,Tid.)
	72137 Discharge,tide fltrd(Mean)

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

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USGS Water-Year Summary 2024

02246500 ST. JOHNS RIVER AT JACKSONVILLE, FL

LOCATION - Lat 30°19'20", long 81°39'56" referenced to North American Datum of 1927, in sec.44, T.2 S., R.26 E., Duval County, FL, Hydrologic Unit 03080103, in land grant 44, near center of channel under the Acosta Bridge at Jacksonville, 2.6 mi upstream from Arlington River, and 23.0 mi upstream from mouth.

DRAINAGE AREA - 8,850 mi². includes Paynes Prairie, a diked sinkhole area of about 650 mi², which is noncontributing except for pumpage.

SURFACE-WATER RECORDS

PERIOD OF RECORD - February 1954 to September 1970 (volume of flow), October 1970 to September 1971 (gage heights only), October 1971 to September 1974, October 1974 to September 1980 (gage heights only), October 1980 to September 1981, October 1981 to June 1987 (gage heights only), July 1987 to September 1993, October 1993 to July 1996 (gage heights only), August 1996 to September 2010, October 2010 to current year (filtered).

GAGE - Water-stage recorder, acoustic velocity meter, and data-collection platform. Datum of gage is 9.99 ft below NGVD of 1929 and 11.08 ft below NAVD of 1988. Apr. 13, 1966 to Sept. 30, 1971, at site 0.6 mi downstream at same datum. October 1971 to September 1986, water-stage recorder and deflection meter recorder at site 200 ft upstream at same datum. October 1986 to July 1996, water-stage recorder 0.3 mi downstream at same datum. July 24, 1984 to Mar. 13, 1996, auxiliary water-stage recorder about 5.4 mi downstream.

COOPERATION - This gage is monitored in cooperation with the St. Johns River Water Management District, National Groundwater and Streamflow Program and the US Army Corps of Engineers.

REMARKS - Discharge not published some days, due to bad or missing velocity data. The stage record published is the maximum and minimum tide event for each calendar day. Streamflow at this site is significantly affected by astronomical tides. Daily mean discharge was computed from filtered unit value discharge data. The Godin low-pass filter was used to remove principal tidal frequencies from unit values. By convention, the U.S. Geological Survey has established ebb (seaward) flows as positive flow and flood (landward) flows as negative flows. The residuals are not total freshwater flows but are a combination of freshwater flows and water storage caused by higher and lower mean sea levels and storm surges from tropical storm events. Instantaneous discharge computed from index-velocity linear regression relation and gage height rating. Daily values of discharge and gage height are available online at http://waterdata.usgs.gov/nwis.

EXTREMES OUTSIDE PERIOD OF RECORD - Maximum peak stage of 15.20 ft, Sept. 9, 1964 at present datum, outside the period of discharge record.

WATER-QUALITY RECORDS

PERIOD OF RECORD -

SPECIFIC CONDUCTANCE: October 2015 to current year.
WATER TEMPERATURE: October 2015 to current year.
SALINITY: October 2015 to current year.

INSTRUMENTATION - Water-quality monitor and data-collection platform.

REMARKS - October 2015 to current year; water temperature, specific conductance, and salinity published as instantaneous maximum and minimum and daily mean. Extremes for period of daily record are based on recorded values and may have been exceeded during periods of no record.

EXTREMES FOR PERIOD OF RECORD -

SPECIFIC CONDUCTANCE: Maximum, 50,100 µS/cm @ 25 °C, Oct. 7, 2016; minimum, 326 µS/cm @ 25 °C, Dec. 21, 2017.

WATER TEMPERATURE: Maximum, 33.2 °C, June 28, 2016; minimum, 8.0 °C, Jan. 7, 2018.

SALINITY: Maximum, 32.9 ppth, Oct. 7, 2016; minimum, 0.1 ppth, Dec. 21, 2017.