Carson Sink, swampy area, c.100 sq mi (260 sq km), W Nev.; a remnant of ancient Lake Lahontan. Fallon National Wildlife Refuge is located there. The Carson River (c.125 mi/200 km long), fed by melted snow, flows into the sink. The river's course was followed by California-bound travelers in the 1850s and 1860s. Mercury used in the mining of gold and silver in the latter half of the 19th cent. contributed to massive pollution of the river. Lahontan Dam, part of the Newlands project, impounds river water for irrigation and produces electricity.