Green Run is a tributary of Spring Brook in Lackawanna County, Pennsylvania, in the United States. It is approximately 4.7 miles (7.6 km) long and flows through Spring Brook Township, Roaring Brook Township, and Scranton. The watershed of the stream has an area of 4.32 square miles (11.2 km2). It is considered to be Class A Wild Trout Waters throughout its entire length. Numerous macroinvertebrate taxa also inhabit the stream. The surficial geology in the vicinity of the stream's lower reaches mainly consists of Wisconsinan Till, bedrock, and Boulder Colluvium.