Physical and chemical characteristics of water in coal-mine ponds of eastern Oklahoma.

Coal-mine ponds cover 4000 acres and have a storage capacity of about 100 000 acre-feet. They are important wild-life habitats and contribute locally to agricultural and municipal water supply. The physical and chemical properties of the water are very variable. By and large, the pond waters showed a lack of mixing and thermal stratification with bottom to surface temperatures differing by up to 30oC over 20 ft depth in July. The medium pH was 7.7, except for ponds associated with the Secor coal bed (pH 3.3). Sulphate was the principal ion in the mine pond water. Other chemicals varied with the associated coal-bed. Chloride concentrations were 11 mg/L or less, except for ponds associated with the Dowson coal (140 mg/L). Dissolved concentration was low 40 mu g/L, except in ponds associated with the Secor (3000 mu g/L and Dowson (2100) coals. Dissolved manganese was less than 1500 micrograms/L except for Secor (35 000), Dowson (4300) and Weir-Pittsburg (3700 micrograms/L). -M.J.Haigh