USGS Water-Year Summary 2024

08143000 Lake Brownwood near Brownwood, TX

LOCATION - Lat 31°50'13", long 99°00'13" referenced to North American Datum of 1927, Brown County, TX, Hydrologic Unit 12090107, on abandoned service outlet structure near center of dam on Pecan Bayou, 0.2 mi downstream from Jim Ned Creek, 8.0 mi north of Brownwood, and 57.1 mi upstream from mouth.

DRAINAGE AREA - 1,565 mi².

REVISIONS HISTORY -

WSP 1212: 1948-50. WDR TX-81-3: Drainage area.

Revisions: Elevation for the period Oct. 20, 2018 to Nov. 29, 2018, were revised on May 07, 2020 based on deletions of dubious data in the elevation record.

SURFACE-WATER RECORDS

PERIOD OF RECORD - July 1933 to May 1941, Nov. 1944 to Sept. 1986, and Feb. 1999 to Sept. 2002 (contents), Oct. 2002 to current year. Fragmentary records July 1934 to Apr. 1935 and Oct. 1940 to May 1941. Prior to Oct. 1970, published as "Brownwood Reservoir". PERIOD OF RECORD, Water-Quality.-- CHEMICAL DATA: Oct. 1970 to Apr. 1984. BIOCHEMICAL DATA: Oct. 1970 to Sept. 1973.

GAGE - Water-stage recorder. From July 1933 to May 1941, July 23, 1946 to May 12, 1948, non-recording gage at irrigation outlet structure near right end of dam, Nov. 21, 1944 to July 22, 1946, water-stage recorder on irrigation outlet structure near right end of dam, May 13, 1948 to June 30, 1949, water-stage recorder in right downstream corner of outlet control tower, July 1, 1949 to Sept. 30, 1986, nonrecording gage at irrigation outlet structure near right end of dam, all at datum 0.50 ft. higher. Prior to Feb. 1999, non-recording gages at the same site at datum 0.50 ft. higher. Feb. 1999 to May 20, 2022, datum of the gage set to 0.00 ft. above NGVD29. May 20, 2022 to present date, datum of the gage set to 0.00 ft. above NAVD88 . Satellite telemeter at station.

COOPERATION - Texas Water Development Board, TWDB, and the U.S. Geological Survey, USGS.

REMARKS - The lake is formed by a rolled earthfill dam, 1,580 ft. long. The dam was completed in 1933 and deliberate impoundment began in July 1933. In Aug. 1983, work was completed to reinforce backside of dam, which raised the top 20 ft. The uncontrolled emergency spillway is a broad-crested weir 479 ft. long located 800 ft. to left of dam. The controlled service spillway consists of two 48-inch horseshoe-shaped concrete conduits. Water is used for irrigation, municipal, and industrial supply. Flow is affected at times by discharge from the flood-detention pools of 59 floodwater-retarding structures with a combined capacity of 73,310 acre-ft. These structures control runoff from 353 mi² in the Jim Ned Creek and Pecan Bayou drainage basins. Records of diversions may be obtained from the Brown County Water Improvement District No.1. The dam is owned by Brown County WID No. 1. These provided data regarding the dam structures have not been validated by the USGS and are given in the following table. 

                                                                              Elevation (feet)
Top of dam............................................................         1,470.3
Crest of spillway.....................................................         1,424.9
Lowest gated outlet (invert)..........................................         1,329.8

EXTREMES FOR PERIOD OF RECORD - Maximum contents, 198,000 acre-ft, July 7, 2002, elevation, 1,432.12 ft; minimum contents observed, 11,900 acre-ft, July 15, 1934, elevation, 1,389.0 ft.