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- Water-Year Summary reports summarize a year of hydrologic data in a printer-friendly format.
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USGS Water-Year Summary 2024
02203873 COBBS CREEK AT RAINBOW DR, NEAR DECATUR, GA
LOCATION - Lat 33°42'33.9", long 84°14'21.0" referenced to North American Datum of 1983, Dekalb County, GA, Hydrologic Unit 03070103,
DRAINAGE AREA - 7.97 mi².
REVISIONS HISTORY - Gage datum was revised on Dec. 3, 2020, based on an error in the determination of the gage datum.
SURFACE-WATER RECORDS
PERIOD OF RECORD -
GAGE-HEIGHT: January 2013 to current year. DISCHARGE: January 2013 to current year.
GAGE-HEIGHT: January 2013 to current year. DISCHARGE: January 2013 to current year.
GAGE - Satellite telemetry with a water-stage recorder and continuous water-quality monitor. Datum of gage is 779.22 feet above National American Vertical Datum (NAVD) of 1988.
COOPERATION - DeKalb County Department of Watershed Protection.
REMARKS - Gage-height records are generally good. Discharge records are generally fair except for estimated discharges, which are poor. Additional details on the accuracy of the records can be obtained by contacting the USGS South Atlantic Water Science Center at gs-w-ga_nwisweb_data_inquiries@usgs.gov.
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 3,040 cfs, October 10, 2020; maximum gage-height, 13.33 feet,>October 10, 2020; minimum daily discharge, 1.53 cfs, October 3, 2019.
CLIMATOLOGICAL RECORDS
PERIOD OF RECORD - December 2, 2012 to current year.
INSTRUMENTATION - Tipping-bucket raingage.
WATER-QUALITY RECORDS
PERIOD OF RECORD - November 2013 to current year.
PERIOD OF DAILY RECORD -
SPECIFIC CONDUCTANCE: November 2013 to current year.
pH: November 2013 to current year.
WATER TEMPERATURE: November 2013 to current year.
DISSOLVED OXYGEN: November 2013 to current year.
TURBIDITY: November 2013 to current year.
SPECIFIC CONDUCTANCE: November 2013 to current year.
pH: November 2013 to current year.
WATER TEMPERATURE: November 2013 to current year.
DISSOLVED OXYGEN: November 2013 to current year.
TURBIDITY: November 2013 to current year.
INSTRUMENTATION - Satellite telemetry with a continuous water-quality monitor.
REMARKS -
For period 11/15/2013-09/30/2014: Specific conductance record good. pH record good. Water temperature record good. Dissolved oxygen record fair. Turbidity record poor.
For period 10/01/2014-09/30/2015: Specific conductance record good. pH record fair. Water temperature record good. Dissolved oxygen record fair. Turbidity record poor.
For period 10/01/2015-09/30/2016: Specific conductance record good. pH record fair. Water temperature record good. Dissolved oxygen record fair. Turbidity record poor.
For period 10/01/2016-09/30/2017: Specific conductance record good. pH record fair. Water temperature record good. Dissolved oxygen record fair. Turbidity record poor.
For period 10/01/2017-09/30/2018: Specific conductance record good. pH record fair. Water temperature record good. Dissolved oxygen record fair. Turbidity record poor.
Data for parameter code 63680 (turbidity) were collected using a probe with the following specifications: turbidity, water, monochrome near infra-red LED light, 780-900 nm, detection angle 90 +/-2.5 degrees, FNU (Formazin Nephelometric Units). Hydrologic event 9 indicates a routine sample, while J designates a storm event sample. Laboratory chemical analyses are by RTI Laboratory, Livonia, MI. Laboratory sediment analyses are by the U.S. Geological Survey, Kentucky Sediment Laboratory. Field determinations of discharge, microbiology, specific conductance, pH, water temperature, turbidity, barometric pressure, air temperature, and dissolved oxygen are by the U.S. Geological Survey.
For period 11/15/2013-09/30/2014: Specific conductance record good. pH record good. Water temperature record good. Dissolved oxygen record fair. Turbidity record poor.
For period 10/01/2014-09/30/2015: Specific conductance record good. pH record fair. Water temperature record good. Dissolved oxygen record fair. Turbidity record poor.
For period 10/01/2015-09/30/2016: Specific conductance record good. pH record fair. Water temperature record good. Dissolved oxygen record fair. Turbidity record poor.
For period 10/01/2016-09/30/2017: Specific conductance record good. pH record fair. Water temperature record good. Dissolved oxygen record fair. Turbidity record poor.
For period 10/01/2017-09/30/2018: Specific conductance record good. pH record fair. Water temperature record good. Dissolved oxygen record fair. Turbidity record poor.
Data for parameter code 63680 (turbidity) were collected using a probe with the following specifications: turbidity, water, monochrome near infra-red LED light, 780-900 nm, detection angle 90 +/-2.5 degrees, FNU (Formazin Nephelometric Units). Hydrologic event 9 indicates a routine sample, while J designates a storm event sample. Laboratory chemical analyses are by RTI Laboratory, Livonia, MI. Laboratory sediment analyses are by the U.S. Geological Survey, Kentucky Sediment Laboratory. Field determinations of discharge, microbiology, specific conductance, pH, water temperature, turbidity, barometric pressure, air temperature, and dissolved oxygen are by the U.S. Geological Survey.
EXTREMES FOR PERIOD OF RECORD -
SPECIFIC CONDUCTANCE: Maximum recorded, 1860 microsiemens, January 22, 2018; minimum recorded,18 microsiemens, September 2, 2016.
pH: Maximum recorded, 7.4 units, October 24, 2020, January 28, 2023, and September 20, 2023; minimum recorded, 5.6 units, October 10, 2020.
WATER TEMPERATURE: Maximum recorded, 27.6°C, August 11, 2014; minimum recorded, 0.2°C, January 18, 2018.
DISSOLVED OXYGEN: Maximum recorded, 13.1mg/L, January 18, 2018; minimum recorded, 3.3 mg/L, November 2, 2015.
TURBIDITY: Maximum recorded, >1100 FNU, on several days; minimum recorded, <0.5 FNU many days.
