USGS Water-Year Summary for Site 01481000

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	Available Parameters
	00010 Temperature, water(Max.,Min.,Mean)
	00045 Precipitation(Sum)
	00060 Discharge(Mean)
	00095 Specific cond at 25C(Max.,Min.,Mean)
	00300 Dissolved oxygen(Max.,Min.,Mean)
	00400 pH(Max.,Min.,Med.)
	63680 Turbidity, Form Neph(Mean,Max.,Min.)
	70387 Chloride, wu, by regression(Mean)

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Water year 2025: 2025-10-01 to 2026-09-30

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USGS Water-Year Summary 2025

01481000 BRANDYWINE CREEK AT CHADDS FORD, PA

LOCATION - Lat 39°52'11", long 75°35'37" referenced to North American Datum of 1927, Delaware County, PA, Hydrologic Unit 02040205, on left bank 27 ft upstream from Penn Central Railroad bridge at Chadds Ford, 150 ft upstream from Harvey Run, and 1,200 ft downstream from highway bridge on U.S. Highway 1.

DRAINAGE AREA - 287 mi².

REVISIONS HISTORY -

WSP 756: Drainage area. WSP 1202: 1917-18(M), 1919-20, 1922-31(M), 1932-33, 1934(M), 1936, 1938(P), 1939(M), 1942, 1944-46(M), WDR PA-98-1: 1996-97 (M).

Prior to January 3, 2023, the datum of gage was reported as 150.45 ft above National Geodetic Vertical Datum of 1929.

SURFACE-WATER RECORDS

PERIOD OF RECORD - August 1911 to September 1953, October 1962 to current year. Prior to October 1911, monthly discharge only, published in WSP 1302.

GAGE - Water-stage recorder and crest-stage gage. Datum of gage is 149.7 ft above North American Vertical Datum of 1988. Prior to May 21, 1927, non-recording gage at same site and datum. Prior to January 3, 2023, the datum of gage was erroneously reported as 150.45 ft above National Geodetic Vertical Datum of 1929. Satellite and landline telemetry at station.

COOPERATION - Station established and maintained by the U.S. Geological Survey. Funding for the operation of this station is provided by the Pennsylvania Department of Environmental Protection, Chester County Water Resources Authority, the City of Wilmington, Delaware, and the U.S. Geological Survey.

REMARKS - Flow regulated since November 1973 by Marsh Creek Reservoir (station 01480684) about 17 mi upstream. Records for water years 2014-2016 are good except those for estimated daily discharges, which are poor. Records for water year 2017 are fair except for estimated discharge, which is poor. Records for water year 2018 are fair except Jan 18 - May 3 and estimated discharge, which are poor. Records for water year 2019 are fair except for estimated discharge, which is poor. Records for water year 2020 are fair.

EXTREMES OUTSIDE PERIOD OF RECORD -

Flood of Aug. 19, 1955 reached a stage of 14.64 ft, gage datum; discharge approximately 16,400 ft³/s.

CLIMATOLOGICAL RECORDS

PERIOD OF RECORD - October 2005 to current year.

INSTRUMENTATION - Precipitation gage interfaced with data collection platform.

REMARKS - Precipitation record for water years 2014-2015 is good. Precipitation records for water year 2016 good with the exception of Feb14-16, which is poor. Precipitation record for water years 2017-2018 is good. Since water year 2019, precipitation records are no longer rated.

ECOLOGICAL RECORDS

PERIOD OF RECORD - April 2002 to current year.

REMARKS - Results of benthic surveys can be obtained by contacting the U.S. Geological Survey Pennsylvania Water Science Center, Exton Field Office.

WATER-QUALITY RECORDS

PERIOD OF RECORD - Water years 1963 to current year.

PERIOD OF DAILY RECORD - SPECIFIC CONDUCTANCE: October 1965 to current year. pH: October 1965 to September 1966, December 1971 to current year. WATER TEMPERATURES: October 1964 to current year. DISSOLVED OXYGEN: October 1971 to current year. TURBIDITY: October 2005 to current year.

COOPERATION - Water-quality samples were collected as part of the Pennsylvania Department of Environmental Protection Water-Quality Network (WQN) with cooperation from the Pennsylvania Department of Environmental Protection and Chester County Water Resources Authority.

INSTRUMENTATION - Water-quality monitor since August 1971.

REMARKS -

Since the 2000 water year, pH daily median values are computed instead of pH daily mean values.

The reporting precision of the turbidity probe in low turbidity water is +/-0.3 FNU. The lowest reportable value, 0 FNU, does not necessarily indicate a condition of zero turbidity.

Except for turbidity, data collection of specific conductance, water temperature, pH, and dissolved oxygen are suspended during winter months since 1981 water year. Other interruptions in the record were due to malfunctions of the equipment.

As of October 2013, results from discrete water quality samples collected at this site are available through the U.S. Geological Survey National Water Information System web interface on the "Water Quality for the Nation" webpage. Analyses for pH, water temperature, specific conductance, and dissolved oxygen were performed on site. All other sample analyses were performed at the Pennsylvania Department of Environmental Protection laboratory in Harrisburg, Pa. Occasionally, values for filtered parameters may exceed values for the corresponding unfiltered parameter. These results are within the limits of analytical precision and methods. Explanations of sample characteristics are available from the USGS NWISWeb Help System pages: http://waterdata.usgs.gov/nwis/help

Water year 2014 records Water temperature, pH, dissolved oxygen records; specific conductance are rated good, with exception of Feb28 - May27 which are fair; turbidity records are rated good. For water year 2015 Water temperature, specific conductance, pH, and dissolved oxygen records are rated good; turbidity records are rated fair with exception of Feb. 2-17 which are poor. For water year 2016 Water temperature, specific conductance, pH records are rated good, dissolved oxygen records are rated good with exception of Oct 1 - Nov. 2 which are poor; turbidity records are rated fair. For water year 2017 Water temperature, specific conductance, pH, and dissolved oxygen records are rated good, turbidity records are rated fair. For water year 2018 water temperature is rated good, specific conductance is rated good except May 18 - July 2, which are fair, pH, dissolved oxygen, and turbidity records are rated fair.

Beginning in water year 2019, water quality records are not rated as "excellent", "good", "fair", or "poor".

EXTREMES FOR PERIOD OF DAILY RECORD - SPECIFIC CONDUCTANCE: Maximum, 1030 microsiemens/cm (snowmelt), Mar 3, 2015; minimum, 42 microsiemens/cm, Nov 26, 1979. pH: Maximum, 9.8, Apr 9, 1975; minimum, 6.1, Feb 22, 1976. WATER TEMPERATURE: Maximum, 31.2°C, Jul 23, 2011; minimum, -0.1°C, many days during winter periods. DISSOLVED OXYGEN: Maximum, 17.1 mg/L, Dec 5, 1976; minimum, 3.0 mg/L, Jun 21, 1984. TURBIDITY: Maximum 1010 FNU, Aug 7, 2020; minimum, 0 FNU, many days.