USGS Water-Year Summary 2021
07196500 ILLINOIS RIVER NEAR TAHLEQUAH, OK
LOCATION - Lat 35°55'31.97", long 94°55'18.13" referenced to North American Datum of 1983, in SW 1/4 NW 1/4 sec.25, T.17 N., R.22 E., Cherokee County, OK, Hydrologic Unit 11110103, near left downstream abutment of U.S. Highway 62 bridge, 2.2 mi northeast of Tahlequah, 6.7 mi upstream from Baron Fork, and at mile 55.6.
DRAINAGE AREA - 950 mi². From automated delineation using 10-meter National Elevation Dataset digital elevation model data dated 10/01/2006 and Watershed Boundary Dataset dated 10/01/2006, using Albers Equal-Area Projection, North American Datum 1983.
- WDR 2012: Drainage area.
PERIOD OF RECORD - October 1935 to current year. Monthly discharge only for some periods, published in WSP 1311.
GAGE - Water-stage recorder. U.S. Army Corps of Engineers' satellite telemeter at station. Datum of gage is 665.08 feet above NAVD 88. Current datum determined by a GNSS Level II survey REF FRAME: NAD_83(2011)(EPOCH:2010.0000) ITRF2014 (EPOCH:2021.5499)[NAVD88 (Computed using GEOID18)] and tied to RM-19. Prior to 10/01/2021 the datum in use was 664.14 above NGVD 1929, U.S. Army Corps of Engineers datum. Prior to Feb. 23, 1939, nonrecording gage. Prior to Sep. 8, 2011 at site 0.2 mile downstream at same datum
EXTREMES OUTSIDE PERIOD OF RECORD - Flood of January 1916 reached a stage of about 26 ft.
EXTREMES FOR PERIOD OF RECORD - Maximum peak flow is from rating curve extended above 77,000 ft³/s on basis of slope-area measurement of peak flow.
PERIOD OF RECORD - Water years 1960-61, 1975-79, October 1989 to August 1995, July 1996 to current year.