The quality of water discharging from a strip-mined basin and a relatively unmined basin on the Cumberland Plateau in Tennessee are examined and compared. The chemical and aesthetic quality of these waters will directly affect the chemical and aesthetic quality of the water flowing through a proposed national river and recreation area.
Water from the heavily mined New River basin is characterized by neutral pH, low dissolved solids (less than 300 milligrams per liter), and high concentrations of suspended sediment. More than 90 percent of the suspended sediment is silt and clay. Suspended-sediment concentrations in the thousands of milligrams per liter are not uncommon for New River and often impart a highly turbid appearance to the water. Approximately 590,000 tons of suspended sediment were discharged from the New River basin in 1977, as compared to an estimated 20,000 tons from the relatively unmined Clear Fork basin.
In association with these fine-grain suspended sediments are sorbed trace metals. In 1977 the New River basin discharged an estimated 17,000 tons of suspended iron while Clear Fork discharged an estimated 600 tons. Suspended-sediment concentration was found to be highly correlated with both suspended and total trace-metal concentrations. This correlation coupled with the nearly neutral pH of the water indicates that trace metals are transported primarily in the suspended phase.
The most promising indicator of the presence of coal mining was found to be dissolved sulfate. All unmined basins sampled in this study showed dissolved sulfate concentrations less than 20 milligrams per liter, whereas all mined basins had dissolved-sulfate concentrations in excess of 20 milligrams per liter regardless of basin size or discharge.