The objective was to characterize the composition of various sources of water in Oklahoma available for consumption by ruminant livestock. The composition of 34 water samples from 21 locations in 15 counties of the state of Oklahoma was determined. There were 10 samples with a total dissolved solids (TDS) concentration greater than 1,000 mg/kg and that were thus considered brackish. Brackish samples were categorized into US Geological Survey groups based on individual cation and anion levels as percentages of the totals (i.e., 1, Na-HCO 3 dominant: Na% ≥40, HCO 3 % ≥50, and SO 4 % ≤40; 2, Ca-SO 4 dominant: Ca% ≥50, SO 4 % ≥50, Na% ≤30, and Mg% ≤30; 3, Na-Cl dominant: Na% ≥50 and Cl% ≥50). One brackish water sample fit group-1 criteria, with 1,037 mg/kg TDS, 310 mg/kg Na, 361 mg/kg HCO 3 , and 297 mg/kg Cl. Four samples from one county were categorized as group 2, with 2,811 ± 115.5 mg/kg TDS, 526 ± 30.5 mg/kg Ca, 95 ± 26.5 mg/kg Na, 138 ± 18.4 mg/kg Mg, and 1,906 ± 96.6 mg/kg SO 4 . Two samples from different counties were in group 3, with 3,036 ± 1,629.5 mg/kg TDS, 647 ± 345.0 mg/kg Na, 248 ± 164.5 mg/kg Ca, 107 ± 67.9 mg/kg Mg, 1,098 ± 592.9 mg/kg Cl, 587 ± 553.0 mg/kg SO 4 , and 263 ± 21.0 HCO 3 . Three samples were unclassified and could be termed as Na-SO 4 dominant, with 3,067 ± 905.3 mg/kg TDS, 575 ± 263.3 mg/kg Na, 276 ± 34.1 mg/kg Ca, 96 ± 2.6 mg/kg Mg, 1,500 ± 619.5 mg/kg SO 4 , 319 ± 22.8 mg/kg Cl, and 290 ± 42.2 mg/kg HCO 3 . Brackish water characteristics can vary markedly even within a state, and mineral levels of some sources may not be closely aligned with common categorizations.