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USGS Water-Year Summary 2024
08012150 Mermentau River at Mermentau, LA
LOCATION - Lat 30°11'24.0", long 92°35'26.0" referenced to North American Datum of 1983, in sec.14, T.10 S., R.2 W., Jefferson Davis Parish, LA, Hydrologic Unit 08080202, 2 miles south of junction of Bayou Nezpique, 300 feet north of Southern Pacific Transportation Company railroad bridge,at U. S. Highway 90 bridge between Silverwood and Mermentau.
DRAINAGE AREA - 1,381 mi².
SURFACE-WATER RECORDS
PERIOD OF RECORD - August 1941 to September 1984 (gage height only), in files of Corps of Engineers, New Orleans District. October 1984 to September 2015. October 2015 to current year. (unit values only)
GAGE - Water-stage recorder and acoustic velocity meter. Datum of gage is 1.29 ft below NAVD88 GEOID18 EPOCH2010.0000. Datum incorrectly published as below NGVD29 for water years 2003-2012). Prior to October 1984, datum of gage is Mean Low Gulf (MLG).
REMARKS - No estimated daily discharge.
Satellite telemetry at station.
Positive and negative flows at this site are defined by direction and are specified to be parallel to the channel at the gage location. The positive flow direction is south-southwest.
Streamflow at this site is affected significantly by astronomical tides.
Astronomical tides cause significant cycles of approximately 24.84 hours at this site. Because a different portion of the 24.84 hour tidal cycle is averaged in successive daily (24-hour) computations, a systematic secondary oscillation, unrelated to basin hydrology and having a period of about two weeks may be apparent in daily data published from October 1984 to September 2015.
Satellite telemetry at station.
Positive and negative flows at this site are defined by direction and are specified to be parallel to the channel at the gage location. The positive flow direction is south-southwest.
Streamflow at this site is affected significantly by astronomical tides.
Astronomical tides cause significant cycles of approximately 24.84 hours at this site. Because a different portion of the 24.84 hour tidal cycle is averaged in successive daily (24-hour) computations, a systematic secondary oscillation, unrelated to basin hydrology and having a period of about two weeks may be apparent in daily data published from October 1984 to September 2015.
EXTREMES OUTSIDE PERIOD OF RECORD - Maximum gage height, 14.5 ft, August 1940; minimum gage height, -0.94 ft, July 13, 1951.
EXTREMES FOR PERIOD OF RECORD - Maximum daily discharge, 58,000 ft³/s, Nov. 2, 1985. Maximum recorded positive discharge, 47,600 ft³/s, May 18, 2004; maximum gage height, 10.97 ft, Nov 2, 1985; maximum recorded negative discharge, -11,500 ft³/s, Dec. 31, 1984; minimum gage height, -0.77 ft, Sep 24, 2005.
WATER-QUALITY RECORDS
PERIOD OF RECORD - Water years 1953, 1979-1993, 1997 to current year.
PERIOD OF DAILY RECORD - SPECIFIC CONDUCTANCE: April 1980 to September 1982, June 2000 to September 2004.
WATER TEMPERATURE: April 1980 to September 1982, June 2000 to September 2004.
EXTREMES FOR PERIOD OF RECORD - SPECIFIC CONDUCTANCE: Maximum, 631 microsiemens/cm, June 8, 2003; minimum, 45 microsiemens/cm, Feb. 15, 2003.
WATER TEMPERATURE: Maximum, 32.9°C July 21; minimum, 6.0°C Jan. 17, 1982.
