USGS Water-Year Summary for Site 08178000

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	Available Parameters
	00045 Precipitation(Sum)
	00060 Discharge(Mean,Max.,Min.)
	00065 Gage height(Mean)

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

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USGS Water-Year Summary 2024

08178000 San Antonio River at San Antonio, TX

LOCATION - Lat 29°24'34", long 98°29'41" referenced to North American Datum of 1927, Bexar County, TX, Hydrologic Unit 12100301, on right bank, 5 ft downstream from South Alamo Street Bridge in San Antonio, 2.1 mi upstream from San Pedro Creek, and at mile 232.0.

DRAINAGE AREA - 41.8 mi². Flow of river comes from intermittent spring flow and from artesian wells.

SURFACE-WATER RECORDS

PERIOD OF RECORD - Dec. 1895 to June 1906 (periodic discharge measurements), Jan. 1915 to Nov. 1929, Feb. 1939 to Sept. 1997 (daily mean discharge), Oct. 1997 to Sept. 1999 (annual peak discharge), Oct. 1999 to Mar. 2011 (daily mean stage), Apr. 2010 to current (daily mean discharge). PERIOD OF RECORD, Water-Quality.-- CHEMICAL DATA: Dec. 1991 to Aug. 1992, Jan. 1996 to Aug. 1996. BIOCHEMICAL DATA: Dec. 1991 to Aug. 1992, Jan. 1996 to Aug. 1996. PESTICIDE DATA: Dec. 1991 to Aug. 1992, Jan. 1996 to Aug. 1996.

GAGE - Water-stage recorder and concrete control. Datum of gage is 603.080 above NADV88 done 5/1/24. Prior datum of gage was 605.26 ft above NGVD of 1929. Jan. 26, 1915, to Feb. 27, 1916, nonrecording gage at site 1.3 mi upstream at different datum. Feb. 28, 1916, to Apr. 7, 1920, nonrecording gage at site 1.1 mi upstream at different datum. Apr. 8, 1920, to Nov. 16, 1929, Feb. 15, 1939, to Apr. 25, 1967, water-stage recorder in vicinity of South Alamo Street Bridge at datum 7.00 ft higher. Apr. 25, 1967, to May 13, 1969, water-stage recorder at site 307 ft downstream at same datum. May 14, 1969, to Apr. 26, 2000, at site on left bank, 193 ft downstream from South Alamo Street bridge.

REMARKS - Gage moved downstream 1/4 mile below concrete wier. Records fair for Water Year. Since 1926, at least 10% of contributing drainage area has been regulated. Springs emerge intermittently from the Edwards and associated limestones along the Balcones Fault Zone upstream from station. Ground-water discharge into river is discussed by Petit and George, Texas Board of Water Engineers Bulletin 5608, vol. 1 (1956, p. 45). Some records listed in the "Period of Record" for surface water and water quality may not be available electronically. Gage was removed for channel rectification from Nov. 19, 2010 to Feb. 9, 2011.

EXTREMES OUTSIDE PERIOD OF RECORD - Flood of July 5, 1819, equaled or exceeded that of Sept. 10, 1921, from San Fernando Cathedral archives and old Spanish records.

EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 15300 ft³/s Sept. 10, 1921 (gage height 20.14 ft, from floodmark at former site and datum); no flow at times.

AVERAGE DISCHARGE FOR PERIOD OF RECORD - WATER YEARS 1927-1997: 50.8 ft³/s, (36,810 acre-ft/yr).

AVERAGE DISCHARGE FOR PERIOD PRIOR TO REGULATION - 12 years (water years 1915-1926) prior to regulation by Olmos Dam, 90.5 ft³/s (65,570 acre-ft/yr).

CLIMATOLOGICAL RECORDS

PERIOD OF RECORD - Oct. 2011 to current

INSTRUMENTATION - Unshielded, standard 8-in. diameter, tipping bucket raingage, 8 ft above land surface, with satellite telemetry.