USGS Water-Year Summary 2024

07072500 BLACK RIVER AT BLACK ROCK, AR

LOCATION - Lat 36°06'09", long 91°05'52" referenced to North American Datum of 1983, in NW 1/4 NW 1/4 sec.21, T.17 N., R.1 W., Lawrence County, AR, Hydrologic Unit 11010009, on right bank beneath U.S. HWY 63 bridge at Black Rock, 3.7 mi downstream from Spring River, and at river mile 69.3.

DRAINAGE AREA - 7,370 mi².

REVISIONS HISTORY - WSP 1211: 1930 to 1931. WDR Arkansas 1973: Drainage area.

SURFACE-WATER RECORDS

PERIOD OF RECORD - Oct 1929 to Sep 1931 and Oct 1939 to current year. Gage height records collected since 1904 in same vicinity are contained in reports of National Weather Service.

GAGE - Water-stage recorder.  Datum of gage is 229.48 ft above NAVD of 1988, (Reference Frame NAD_83 (2011) (EPOCH:2010.0000) GEOID18). 

Prior to August 06, 2024, the datum of gage was 229.56 ft NGVD of 1929 

Prior to Aug 1, 1946, nonrecording gage at site 900 ft upstream at same datum. Aug 1, 1946 to Aug 17, 1978, nonrecording gage at site 650 ft upstream at same datum.

EXTREMES OUTSIDE PERIOD OF RECORD - Flood of Aug 1915 reached a stage of 31.9 ft, from records of National Weather Service, discharge 160,000 ft³/s.

EXTREMES FOR PERIOD OF RECORD - Maximum discharge 190,000 ft³/s Dec 4, 1982 from rating curve extended above 105,000 ft³/s. Maximum peak stage 31.51 ft Dec 4, 1982 from floodmarks

EXTREMES FOR PERIOD PRIOR TO REGULATION - Annual mean 8,827 ft³/s prior to regulation, water years 1930 to 1931 and 1940 to 1947, 7,854 ft³/s