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USGS Water-Year Summary 2024
08078000 Chocolate Bayou near Alvin, TX
LOCATION - Lat 29°22'16.7", long 95°19'22.2" referenced to North American Datum of 1927, Brazoria County, TX, Hydrologic Unit 12040204, on left bank 13 ft downstream from bridge on Farm Road 1462, 5.9 mi southwest of Alvin, and 6.9 mi upstream from State Highway 35.
DRAINAGE AREA - 87.7 mi².
SURFACE-WATER RECORDS
PERIOD OF RECORD - Aug. to Oct. 1944 and Mar. to Dec. 1946 (low-water records during irrigation season), Jan. 1947 to Feb. 1958, and Mar. 1958 to Feb. 1959 (discharge measurements only), Mar. 1959 to current year.
PERIOD OF RECORD, Water-Quality.--
CHEMICAL DATA: Feb. 1968 to Aug. 1985.
BIOCHEMICAL DATA: Feb. 1968 to Aug. 1985.
BIOLOGICAL DATA: May 1971 to Aug. 1985.
PESTICIDE DATA: May 1971 to Feb. 1979.
SEDIMENT DATA: Feb. 1978 to Aug. 1985.
GAGE - Water-stage recorder. Datum of gage is 0.31 ft above NGVD of 1929. Prior to May 3, 1959, nonrecording gage or water-stage recorders located at various sites from 900 to 1,400 ft upstream and at datum 3.00 ft higher. May 3, 1959 to Sept. 30, 1987, present site, at datum 10.00 ft higher. Satellite telemeter at station.
REMARKS - No known regulation. Stage-discharge relation is affected by seasonal vegetation during most years. Large area of riceland above station is irrigated with water diverted from the Brazos River. Low flow from Apr. to Oct. is largely drainage from these irrigated lands. Diversions for irrigation occur above station. Gage height associated with historical peak discharge is referenced to current (2014) datum. Some records listed in the "Period of Record" for surface water and water quality may not be available electronically.
EXTREMES OUTSIDE PERIOD OF RECORD - Flood of July 14, 1939, reached a stage of 32.5 ft, present site and datum, adjusted from floodmark 1,700 ft to right and 550 ft upstream from present gage, on basis of slope of flood of Oct. 8, 1949, from information by local residents.
