USGS Water-Year Summary for Site 08160400

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	Available Parameters
	00060 Discharge(Max.,Min.,Mean)
	00065 Gage height(Max.,Min.,Mean)
	00065 Gage height(Mean) [(2)]

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Water year 2023: 2022-10-01 to 2023-09-30

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USGS Water-Year Summary 2023

08160400 Colorado River above La Grange, TX

LOCATION - Lat 29°54'44", long 96°54'13" referenced to North American Datum of 1927, Fayette County, TX, Hydrologic Unit 12090301, at right downstream end of bridge on new State Highway 71, 1.4 mi upstream from Buckners Creek, and at mile 177.

DRAINAGE AREA - 40,874 mi² of which 11,403 mi² probably is noncontributing.

REVISIONS HISTORY -

August 08, 2017 thru May 19, 2020, were revised; daily value discharges.

SURFACE-WATER RECORDS

PERIOD OF RECORD - Dec. 1979 to Sept. 1982 (discharge measurements only), Apr. 1988 to current year.

GAGE -

Water-stage recorder. Satellite telemetry at station.

Datum of gage: 209.972 ft NAVD88 based on a Level 2 Static GNSS survey processed through OPUS, Ref Frame: NAD83 (2011)(EPOCH:2010.0000) ITRF2014 (EPOCH:2022.8185) and Geoid 18. The survey was completed October 26, 2022 while occupying a TRM that was referenced to local datum via differential levels.

Prior to October 26th, 2022, the datum of gage was 210.04 ft NGVD29 determined by levels from USC&CS benchmark Y765 1943. Dec. 12, 1979, to Sept. 30, 1982, discharge measurements only were made at old State Highway 71 bridge, 1.0 mi downstream and at different datum. Radio 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 - Since installation of gage in 1988, at least 10% of contributing drainage area has been regulated. At times, low-flow releases from Lake Travis are made for generation of electric power and to fulfill downstream water contracts. There are many diversions above station for irrigation and municipal supply. Some records listed in the "Period of Record" for surface water and water quality may not be available electronically.

EXTREMES OUTSIDE PERIOD OF RECORD - Maximum stage since at least 1869, about 56.7 ft on July 9, 1869 (from marble high-water marker in LaGrange). Stages of other floods are as follows: Dec. 5, 1913, 56.4 ft, from floodmark; June 17, 1935, 50.84 ft, from floodmarks (discharge 255,000 ft³/s from rating curve extended above 200,000 ft³/s); July 27, 1938, 42.95 ft (discharge, 200,000 ft³/s). These data were collected and published at streamflow station Colorado River at La Grange (08160500) at a site 2.6 mi downstream and at a datum different than at present site.