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USGS Water-Year Summary 2024
08150000 Llano River near Junction, TX
LOCATION - Lat 30°30'15", long 99°44'03" referenced to North American Datum of 1927, Kimble County, TX, Hydrologic Unit 12090204, on right bank 960 ft upstream from abandoned low-water crossing, 1.0 mi east of Junction, 2.6 mi downstream from bridge on Interstate Highway 10, 2.8 mi downstream from confluence of North and South Llano Rivers, 5.3 mi upstream from Johnson Fork, and 114.8 mi upstream from mouth.
DRAINAGE AREA - 1,854 mi² of which 5 mi² probably is noncontributing.
REVISIONS HISTORY - WSP 568: 1915-16, 1918-20, 1922. WSP 1922: 1920, 1923. WDR TX-81-3: Drainage area.
SURFACE-WATER RECORDS
PERIOD OF RECORD - Sept. 1915 to May 1993, Oct. 1997 to current year.
GAGE - Water-stage recorder. Datum of gage is 1,634.40ft above NAVD88 as determined by GNSS survey. Prior to Jan. 19, 2023, the datum of gage was 1,634.32ft above NGVD of 1929. Prior to Aug. 14, 1925, nonrecording gage, and Aug. 14, 1925, to May 17, 1940, and Aug. 18, 1944, to Oct. 12, 1981, water-stage recorder at site 5,330 ft downstream at datum 6.0 ft lower, designated as regular gage (destroyed by flood of Oct. 13, 1981). Prior to June 13, 1990, at datum 2.0 ft higher. Radio telemeter at station. Satellite telemeter at station.
COOPERATION - Lower Colorado River Authority provides operation and maintenance of the gage and verification of stage-discharge relation at low stages. U.S. Geological Survey maintains stage-discharge relation at medium to high stages, computes and publishes streamflow record.
REMARKS - This station is regulated by the Lake Junction dam approximately 3.31mi. upstream on the South Llano River. This dam is located 0.18mi. upstream of the confluence of the N. Llano River and the S. Llano River which forms the Llano River. This dam was built in January of 1964. There are diversions above station for irrigation. Some records listed in the period of record may not be available electronically.
EXTREMES OUTSIDE PERIOD OF RECORD - Maximum stage since at least 1875, that of June 14, 1935. A major flood in 1889 was the highest known prior to June 14, 1935.
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 319,000 ft³/s Jun 14, 1935 (gage-height, 43.30 ft, from floodmark).
