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USGS Water-Year Summary 2024
08185000 Cibolo Creek at Selma, TX
LOCATION - Lat 29°35'38", long 98°18'39" referenced to North American Datum of 1927, Bexar County, TX, Hydrologic Unit 12100304, on right bank 0.6 mi downstream from Missouri-Kansas-Texas Railroad Co. bridge and 0.9 mi upstream from bridge on Interstate Highway 35 at Selma.
DRAINAGE AREA - 274 mi².
REVISIONS HISTORY - WSP 1923: Drainage area. WSP 1712: 1960 (M).
SURFACE-WATER RECORDS
PERIOD OF RECORD - Mar. 1946 to current year.
GAGE - Water-stage recorder. Datum of gage is 728.717 ft. above NADV88 on 09/10/2024. Prior datum of gage was 728.34 ft above NGVD of 1929. Satellite telemeter at station.
REMARKS - Records fair. Beginning in 1978, flow has been affected at times by discharge from the flood-detention pool of a Soil Conservation Service multiple-purpose floodwater-retarding structure with a detention-capacity of 4,693 acre-ft., this structure controls runoff from 19.8 mi². Considerable flow from Cibolo Creek enters the Edwards and associated limestones in the Balcones Fault Zone, which crosses the basin between this station and Cibolo Creek at Interstate Highway 10 above Boerne (station 08183850). One known diversion. No flow at times. Some records listed in the "Period of Record" for surface water and water quality may not be available electronically.
EXTREMES OUTSIDE PERIOD OF RECORD - A stage of 26 ft occurred in 1889, from information by local residents. Maximum stage since at least 1869, that of Oct. 17, 1998.
EXTREMES FOR PERIOD OF RECORD - For period of regulated streamflow, water years 1978 to present, maximum peak discharge; 98,100 cfs on Oct 17, 1998. Maximum peak stage from a floodmark; 35.37 ft on Oct 17, 1998.
EXTREMES FOR PERIOD PRIOR TO REGULATION - WATER YEARS, 1946-1977: Maximum discharge, 65,000 ft³/s July 16, 1973 (gage height, 26.20 ft, from floodmark),from rating curve extended above 16,000 ft³/s on basis of field estimate of 54,000 ft³/s and contracted-opening measurement of 65,000 ft³/s; no flow most of the time.
AVERAGE DISCHARGE FOR PERIOD PRIOR TO REGULATION - 31 years (water years 1946-1977), 15.6 ft³/s (11,300 acre-ft/yr).
