Saline waters reach the surface in a large area of the southeast Copper River Lowland, Alaska, and are estimated to add more than 200 tons of chloride per day to the Copper River. Most saline springs in the area are similar in composition to connate waters of the Na-Ca-Cl type, and are accompanied by gases composed mainly of methane and nitrogen. In the east part of the saline area three springs discharge Na-Cl-HCO₃ type water that is thought to be basically water of the Na-Ca-Cl type admixed with water rich in HCO₃, B, and SO₄. These springs discharge CO₂ gas. It is postulated that the Na-Cl-HCO₃ waters are the result of mixing at depth of waters of the Na-Ca-Cl type with fluids of volcanic, metamorphic, or other ori in. Chemical data slightly favor a metamorphic origin for the admixing fluids.

The saline water is thought probably to originate in Upper Cretaceous or older marine sedimentary rocks which are inferred to underlie the southern part of the Copper River Lowland.