USGS Water-Year Summary for Site 08181500

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	Available Parameters
	00010 Temperature, water(Max.,Min.,Mean)
	00045 Precipitation(Sum)
	00060 Discharge(Max.,Min.,Mean)
	00065 Gage height(Max.,Min.,Mean)
	00095 Specific cond at 25C(Max.,Min.,Mean)
	00300 Dissolved oxygen(Max.,Min.,Mean)
	00400 pH(Max.,Min.)
	63680 Turbidity, Form Neph(Max.,Min.,Mean)

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

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USGS Water-Year Summary 2024

08181500 Medina River at San Antonio, TX

LOCATION - Lat 29°15'50", long 98°29'26" referenced to North American Datum of 1927, Bexar County, TX, Hydrologic Unit 12100302, on right bank at downstream side of bridge on Old Pleasanton Rd. in San Antonio, and 8.0 mi upstream from mouth.

DRAINAGE AREA - 1,317 mi².

REVISIONS HISTORY - WSP 1562: 1957. WSP 1923: Drainage area.

SURFACE-WATER RECORDS

PERIOD OF RECORD - Oct. 1929 to Dec. 1930, July 1939 to current year. Oct. 1929 to Dec. 1930, records below about 50 ft³/s in connection with seepage investigation, published as "at Losoya". Published as "near San Antonio" July 1939 to Sept. 1970.

GAGE - Water-stage recorder. Datum of gage is 451.156 ft. above NADV88. Datum of gage is 439.03 ft above NGVD of 1929 (levels by U.S. Army Corps of Engineers). Oct. 1929 to Dec. 1930, nonrecording gage at Losoya 1.5 mi downstream at different datum. July 27, 1939 to Sept. 30, 1987, at site near left bank at downstream side of pier of upstream Hwy 281 bridge at same datum. Oct. 1, 1987 to Apr. 1, 2003, near right bank at upstream side of pier of upstream Hwy 281 bridge at same datum. Apr. 2, 2003 to Mar. 9, 2005, at right end of downstream side of downstream Hwy 281 bridge at same datum. Satellite telemeter at station.

REMARKS - Since installation of gage in water year 1939, at least 10% of contributing drainage area has been regulated. Streamflow is lost into the Edwards and associated limestones in the Balcones Fault Zone that cross the basin between the upstream end of Medina Lake and about 5 mi downstream from Medina Dam, or 0.9 mi downstream from the Medina Diversion Dam. Several small diversions below Medina Diversion Lake. Wastewater effluent from the Mitchell Lake, Leon Creek, and Medio Creek wastewater treatment plants was discharged into the Medina River above 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, 55 ft, prior to construction of Medina Dam in 1913, from information by Texas Department of Transportation.

CLIMATOLOGICAL RECORDS

PERIOD OF RECORD - Nov. 2009 to current year.

INSTRUMENTATION - Unshielded, standard 8-in. diameter, tipping bucket raingage,mounted 3.0 ft. above gage shelter, with satellite telemetry. Datum of gage is 439.03 ft above NGVD 1929.

WATER-QUALITY RECORDS

PERIOD OF RECORD - CHEMICAL DATA: June 1965, Jan. 1968, Apr. 1971 to Aug. 1995, Feb. 1997 to Mar. 1998. BIOCHEMICAL DATA: June 1965, Jan. 1968, Apr. 1971 to Aug. 1995, Feb. 1997 to Mar. 1998. BIOLOGICAL DATA: June 1986, Dec. 1992 to Mar. 1998. PESTICIDE DATA: Apr. 1971 to May 1984, Dec. 1992 to Mar. 1998. RADIOCHEMICAL DATA: Dec. 1980 to June 1981.

PERIOD OF DAILY RECORD - SPECIFIC CONDUCTANCE: Jan. 1987 to Sept. 2000; Mar. 2005 to current year. pH: Jan. 1987 to Sept. 2000; Mar. 2005 to current year. WATER TEMPERATURE: Jan. 1987 to Sept. 2000; Mar. 2005 to current year. DISSOLVED OXYGEN: Jan. 1987 to Sept. 2000; Mar. 2005 to current year. TURBIDITY: Mar. 2005 to current year.

INSTRUMENTATION - A 4-parameter continuous water-quality monitor from Jan. 1987 to Sept. 2000; Mar. 2005 turbidity probe added to site. Mar. 2005 to current year.

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, 1410 microsiemens/cm, July 10, 2012, Mar. 7, 8, 2007; minimum, 30 microsiemens/cm, July 16, 1990. pH: Maximum, 9.1 standard units, Dec 12, 2013, May 13, 2014; minimum, 7.2 standard units, Jun 23, 24, 2014. WATER TEMPERATURE: Maximum, 33.4°C, Aug 11, 2014; minimum, 9.0°C, Jan. 11, 1988, Dec. 23, 1989. DISSOLVED OXYGEN: Maximum, 14.3 mg/L, Feb. 18, 1997; minimum, 1.4 mg/L, Sept. 25, 2000. TURBIDITY: Maximum, 1,530 FNU June 29, 2007; minimum, 1.0 FNU, Nov. 18, 2005, Jan. 25, 2014, Jan. 14-15, 2018.