Numerous macroinvertebrate taxa have been observed in the stream and boreal forest trees inhabit wetlands in the watershed.

The stream then turns northwest for several tenths of a mile before receiving Lake Run, its first named tributary, from the left.

It continues flowing north-northwest and receives the tributary Kellum Creek after several tenths of a mile.

The stream continues flowing north-northwest, crossing Pennsylvania Route 435 and reentering Roaring Brook Township several tenths of a mile further downstream.

It then crosses Interstate 84 and receives the tributary Rock Bottom Creek from the right as its valley becomes much deeper and narrower.

It continues flowing north-northwest for more than a mile alongside Pennsylvania Route 435 before turning south-southwest and briefly entering Dunmore before reentering Roaring Brook Township.

It passes through the Scranton Water Company Reservoir and receives the tributary Little Roaring Brook from the right before turning south and then west.

[5] In the early 1900s, the stream was polluted by waste from coal mines 5 miles (8.0 km) upstream of its mouth.

[7] In the 1960s and 1970s, several measurements of the concentration of dissolved oxygen in Roaring Brook at Scranton ranged from 10.0 to 12.6 milligrams per liter.

[7] The concentration of fluoride in Roaring Brook at Scranton was once measured to be 0.2 milligrams per liter (in unfiltered water only).

[7] The peak annual discharge at the mouth of Roaring Brook has a 10 percent chance of reaching 5260 cubic feet per second.

[3][11] The waterfall is a cascade with a height of 22 feet (6.7 m) and cuts through a soft siltstone formation and flows over conglomerate.

However, the lower reaches are mountainous, with steep, high hills and a narrow valley from Elmhurst downstream to Dunmore.

[4] An abandoned water power dam known as Step Falls is located on the stream in the Nay Aug Gorge.

[13] Upstream of Nay Aug, the channel of Roaring Brook is mainly natural and ranges in width from 40 to 60 feet (12 to 18 m).

[4] The average annual rate of precipitation in the watershed of Roaring Brook ranges from 35 to 45 inches (89 to 114 cm).

[4] Wetlands in the watershed of Roaring Brook include the Freytown and Hollister swamps, which are located near the stream's headwaters.

[16][17] The stream was historically known as Nay-aug.[10] Nay-aug is a name derived from a Native American language meaning "roaring".

[19] An iron works industry known as the Slocum Brothers Mill was constructed on Roaring Brook 0.5 miles (0.80 km) upstream of its mouth in 1838.

It struggled at first, but by 1846 managed to get a contract to produce iron T rails for the New York and Lake Erie Railroad.

[21] In the early 1900s, the main industries in the watershed of Roaring Brook included agriculture, brick making, and coal mining.

A steel girder and floorbeam system bridge with a length of 76.1 feet (23.2 m) was also constructed over the stream in that year and was repaired in 2006.

In this flood, floodwaters from Roaring Brook and another nearby stream damaged large areas in the lower-lying parts of Dunmore.

[8] In 1960, the United States Army Corps of Engineers channelized 1 mile (1.6 km) of Roaring Brook.

[5] Upstream of the Hollister Reservoir, Roaring Brook meets the criteria for an Exceptional Value designation.

[15] Wolves, bears, wildcats, and panthers historically inhabited the area in the vicinity of Roaring Brook.

[10] Numerous macroinvertebrate taxa have been observed in Roaring Brook upstream of the Hollister Reservoir, including 16 genera from the orders Ephemeroptera, Plecoptera, and Trichoptera.

[15] Boreal forest trees such as black spruce, paper birch, and tamarack inhabit wetlands in the watershed of Roaring Brook.

Old-growth forests containing oak, pine, and hemlock trees are also present in the Nay Aug Gorge.

[15] In the early 2000s, the Lackawanna River Watershed Conservation Plan recommended constructing a greenway and connecting trail along Roaring Brook.