Roaring Brook (also known as Roaring Branch Creek or Roaring Creek and historically known as Nay-aug) is a tributary of the Lackawanna River in Lackawanna County, Pennsylvania, in the United States. It is approximately long and flows through Covington Township, Madison Township, Moscow, Roaring Brook Township, Elmhurst Township, Dunmore, and Scranton. The watershed of the stream has an area of . Its named tributaries include Little Roaring Brook, Rock Bottom Creek, White Oak Run, Van Brunt Creek, Bear Brook, and East Branch Roaring Brook. It has a high level of water quality for much of its length. However, it is affected by abandoned mining land, stormwater, and other impacts in its lower reaches. Reservoirs in the watershed include the Hollister Reservoir, the Elmhurst Reservoir, and others. The stream also flows through the Nay Aug Gorge and passes over the Nay Aug Falls, which are on the National Register of Geologic Landmarks. It flows through a concrete channel in its lower reaches. The topography of the watershed contains rolling hills in its upper reaches and the mountainous land of the Moosic Mountains in its lower reaches.
Land uses in the watershed of Roaring Brook include forested land, agricultural land, and developed land such as high-density residential land and downtown commercial land. Abandoned mine land also occurs in the watershed and wetlands occur in some areas. Major roads in the stream's drainage basin include Interstate 380, Interstate 84, Pennsylvania Route 435, Pennsylvania Route 590, and Pennsylvania Route 690. Mills and forges were built along the stream in the late 1700s and early 1800s. During the 19th century, there was a substantial coal and iron industry in the watershed. Several railroads were also built in the stream's vicinity. Numerous bridges, including the Harrison Avenue Bridge (which is on the National Register of Historic Places) have been built across the stream as well. Additionally, sites such as the Scranton Iron Furnaces are in its watershed.
Roaring Brook is designated as a High-Quality Coldwater Fishery and a Migratory Fishery for part of its length and a Coldwater Fishery and a Migratory Fishery for the other part of its length. It is also Class A Wild Trout Waters from the Hollister Dam to the Elmhurst Reservoir. Numerous macroinvertebrate taxa have been observed in the stream and boreal forest trees inhabit wetlands in the watershed. A 12-mile (19-kilometer) rail trail connecting the Lackawanna River Heritage Trail to the Poconos via the Roaring Brook Corridor has been proposed.
Course
Roaring Brook begins in a small wetland in Covington Township, a few tenths of a mile from the border between Lackawanna County and Wayne County. It flows west for a few tenths of a mile before turning west-northwest for several tenths of a mile. The stream then turns northwest for several tenths of a mile before receiving Lake Run, its first named tributary, from the left. It then enters the Hollister Reservoir, where it receives the tributary East Branch Roaring Brook from the right. After passing through the reservoir, the stream turns north-northwest. It soon begins flowing along the border between Covington Township and Madison Township and begins to flow alongside Pennsylvania Route 435. The stream enters Moscow and receives the tributary Bear Brook from the right and the tributary Van Brunt Creek from the left. It continues flowing north-northwest and receives the tributary Kellum Creek after several tenths of a mile.