USGS Water-Year Summary for Site 08181800

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	Available Parameters
	00010 Temperature, water(Max.,Min.,Mean)
	00045 Precipitation(Sum)
	00060 Discharge(Mean,Max.,Min.)
	00065 Gage height(Max.,Min.,Mean)
	00095 Specific cond at 25C(Max.,Min.,Mean)
	00300 Dissolved oxygen(Max.,Min.,Mean)
	00400 pH(Max.,Min.)

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

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USGS Water-Year Summary 2024

08181800 San Antonio River near Elmendorf, TX

LOCATION - Lat 29°13'19", long 98°21'20" referenced to North American Datum of 1927, Bexar County, TX, Hydrologic Unit 12100301, at downstream side of bridge on Farm Road 1604, 2.7 mi southwest of Elmendorf, 3.3 mi downstream from Braunig Plant Lake, and 203.0 mi upstream from mouth.

DRAINAGE AREA - 1,743 mi².

SURFACE-WATER RECORDS

PERIOD OF RECORD - Sept. 1962 to current year.

GAGE - Water-stage recorder. Datum of gage is 380.00 ft above NGVD of 1929. Sept. 12, 1962 to Dec. 19, 1980, at site 2.5 mi upstream at different datum. Dec. 19, 1980 to Dec. 23, 1986, water-stage recorder at current site and datum. Dec. 24, 1986 to June 15, 1993, water-stage recorder at site 2.8 mi upstream at different datum. Satellite telemeter at station.

REMARKS - Since installation of gage in water year 1962, at least 10% of contributing drainage area has been regulated. Water is diverted above station from Medina River for irrigation in the vicinity of Devine and Lytle, with some water diverted for irrigation near San Antonio. The city of San Antonio discharges wastewater effluent into the San Antonio River above the station from their Leon Creek, Medio Creek, Salado Creek, Dos Rios, and Mitchell plants. The San Antonio City Public Service Board diverts water into and returns water from Braunig Lake and Calaveras Lake upstream from this station. Some records listed in the "Period of Record" for surface water and water quality may not be available electronically.

EXTREMES OUTSIDE PERIOD OF RECORD - Maximum stage since at least 1900, 61 ft in 1946. Second highest stage was 53 ft in 1913, from information by local residents at site and datum in use prior to Dec. 19, 1980.

WATER-QUALITY RECORDS

PERIOD OF RECORD - CHEMICAL DATA: Sept. 1964 to Sept. 2004. Dec. 2006 to Oct. 2007. BIOCHEMICAL DATA: Jan. 1968 to Sept. 2004. PESTICIDE DATA: Jan. 1968 to Sept. 1981, Dec. 1992 to Sept. 2004. RADIOCHEMICAL DATA: Dec. 2006 to Oct. 2007.

PERIOD OF DAILY RECORD - SPECIFIC CONDUCTANCE: Oct. 1966 to current year. pH: June 1984 to current year. WATER TEMPERATURE: Oct. 1966 to current year. DISSOLVED OXYGEN: June 1984 to current year. TURBIDITY: Jan 2011 to current year. Data from Oct 11, 2011 to Nov 10, 2011 required a multiplier of 10 to adjust for transmission errors. The corrected data is available through NWISWeb.

INSTRUMENTATION - A 4-parameter continuous water-quality monitor since June 1984. Turbidity was added Jan 2011. Nitrate sensor added Apr. 2018

REMARKS - Interruptions in the record may be due to malfunctions of the instrument, no flow conditions, or data corrections exceeding allowable criteria, which were deleted. Other than no flow conditions, minimum and maximum extremes may have occurred during period of missing record.

EXTREMES FOR PERIOD OF DAILY RECORD - SPECIFIC CONDUCTANCE: Maximum, 1,610 micro siemens/cm, Aug. 09, 2023; minimum, 102 micro siemens/cm, Oct. 17, 1999. pH: Maximum, 9.0 standard units, June 16, 17 1993; minimum, 7.0 standard units, Jan. 11, 1989, Oct. 25,28, 1998, Aug. 29, 2002, Aug 8,9,10, 2014, Sept. 16, 2015. WATER TEMPERATURE: Maximum, 34.1°C, June 28, 2009; minimum, 5.5°C, Jan. 10, 1973. DISSOLVED OXYGEN: Maximum, 16.5 mg/L, Mar. 4, 2002; minimum, 0.5 mg/L, Oct 28, 2011. TURBIDITY: Maximum, 2380 FNU May 5, 2016; minimum, .4 FNU, Nov 6, 9, 2011. NO3+NO2,water, Maximum, 24.3 mg/L, Sept 29, 2021; minimum 0.1 mg/L., Sept 10, 2020.