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USGS Water-Year Summary 2024
01491000 CHOPTANK RIVER NEAR GREENSBORO, MD
LOCATION - Lat 38°59'49.9", long 75°47'08.9" referenced to North American Datum of 1983, Caroline County, MD, Hydrologic Unit 02060005, on right bank at highway bridge (removed), 0.1 mi upstream from Gravelly Branch, 2.0 mi northeast of Greensboro, and 60 mi upstream from mouth.
DRAINAGE AREA - 113 mi².
REVISIONS HISTORY - WSP 1622: 1948. WDR MD-DE-79-1: 1961(P).
SURFACE-WATER RECORDS
PERIOD OF RECORD - January 1948 to current year.
GAGE - Water-stage recorder, concrete control, and crest-stage gage. Datum of gage is 2.73 ft above North American Vertical Datum of 1988.
REMARKS - Water Years 2021-2024: Records good, except those above 1,000 ft³/s which are poor. No estimated discharges.
Water Year 2020: Records good, no estimated discharges.
Water Year 2019: Records good, except those for estimated discharges, which are poor.
Water Years 2017-2018: Records good, no estimated discharges.
Water Year 2016: Records good, no estimated daily discharges.
Water Years 2014-2015: Records good, except those for estimated daily discharges, which are poor.
Water Year 2013 and prior years' accuracy statements can be found in Annual Water Data Reports.
Diversions for irrigation of about 500 acres, upstream from station. U.S. Geological Survey satellite data-collection platform at station.
Diversions for irrigation of about 500 acres, upstream from station. U.S. Geological Survey satellite data-collection platform at station.
EXTREMES OUTSIDE PERIOD OF RECORD - Flood in 1935 is believed to have been higher than that of Aug. 4, 1967, from information by local residents.
WATER-QUALITY RECORDS
PERIOD OF DAILY RECORD - SPECIFIC CONDUCTANCE: April 2023 to current year. WATER TEMPERATURE: April 2023 to current year. pH: April 2023 to current year. TURBIDITY: April 2023 to current year. DISSOLVED OXYGEN: April 2023 to current year.
INSTRUMENTATION - Multi-parameter water quality sonde, April 2023 to current year.
REMARKS - Missing data due to equipment malfunction.
EXTREMES FOR PERIOD OF DAILY RECORD - WATER TEMPERATURE (April 2023 until present): Minimum: 0.4 degrees Celsius, first occurrence, January 22, 2024; Maximum: 29.2 degrees Celsius, July 28, 2023.
SPECIFIC CONDUCTANCE (April 2023 until present): Minimum: 51.0 microsiemens per centimeter, first occurrence, January 11, 2024; Maximum 178 microsiemens per centimeter, first occurrence, September 07, 2023.
pH (April 2023 until present): Minimum: 6.0 standard units, January 11, 2024; Maximum 7.8 standard units, September 09, 2023.
DISSOLVED OXYGEN (April 2023 until present): Minimum 4.9 milligrams per liter, September 08, 2023 ; Maximum 13.5 milligrams per liter, first occurrence on January 01, 2024.
TURBIDITY (April 2023 until present): Minimum 1.7 formazin nephelometric units, November 1, 2023; Maximum 64.6 formazin nephelometric units, December 20, 2023.
Previous Data Collection Efforts:
WATER TEMPERATURE (water years 1975-81, 1985, 1988-91, 2011, 2012): Maximum, 30.2°C, July 23, 2011; minimum, -0.5°C, December 16, 2010.
SPECIFIC CONDUCTANCE (water years 1975-81, 1988, 1990-91, 2011, 2012): Maximum, 433 microsiemens/cm, Mar. 2, 2011; minimum, 33 microsiemens/cm, Aug. 28, 2011.
SEDIMENT CONCENTRATION: Maximum daily mean, 107 mg/L, December 26, 1986; minimum daily mean, 1 mg/L, on many days during water years 1982-91.
SEDIMENT LOAD: Maximum daily, 448 tons, December 26, 1986; minimum daily, 0.02 tons, August 30, September 7, 1982, July 25, 1986, October 16, 23, 26, 27, 1987, September 23, 1988
SPECIFIC CONDUCTANCE (April 2023 until present): Minimum: 51.0 microsiemens per centimeter, first occurrence, January 11, 2024; Maximum 178 microsiemens per centimeter, first occurrence, September 07, 2023.
pH (April 2023 until present): Minimum: 6.0 standard units, January 11, 2024; Maximum 7.8 standard units, September 09, 2023.
DISSOLVED OXYGEN (April 2023 until present): Minimum 4.9 milligrams per liter, September 08, 2023 ; Maximum 13.5 milligrams per liter, first occurrence on January 01, 2024.
TURBIDITY (April 2023 until present): Minimum 1.7 formazin nephelometric units, November 1, 2023; Maximum 64.6 formazin nephelometric units, December 20, 2023.
Previous Data Collection Efforts:
WATER TEMPERATURE (water years 1975-81, 1985, 1988-91, 2011, 2012): Maximum, 30.2°C, July 23, 2011; minimum, -0.5°C, December 16, 2010.
SPECIFIC CONDUCTANCE (water years 1975-81, 1988, 1990-91, 2011, 2012): Maximum, 433 microsiemens/cm, Mar. 2, 2011; minimum, 33 microsiemens/cm, Aug. 28, 2011.
SEDIMENT CONCENTRATION: Maximum daily mean, 107 mg/L, December 26, 1986; minimum daily mean, 1 mg/L, on many days during water years 1982-91.
SEDIMENT LOAD: Maximum daily, 448 tons, December 26, 1986; minimum daily, 0.02 tons, August 30, September 7, 1982, July 25, 1986, October 16, 23, 26, 27, 1987, September 23, 1988
