Scotch Run is one of the main tributaries of Catawissa Creek in Columbia County, Pennsylvania, in the United States.

Part of Pennsylvania State Game Lands Number 58 is in the watershed and ephemeral natural pool system is located near the stream.

In Main Township, it flows between Nescopeck Mountain and Full Mill Hill for slightly more than half a mile.

[1] Scotch Run joins Catawissa Creek 8.30 miles (13.36 km) upstream of its mouth.

[5] Scotch Run flows over rock of the Mauch Chunk Formation for its entire length.

However, the headwaters of its unnamed tributary, "Trib 27547 to Scotch Run" are on rock of the Pocono Formation.

Mining land in various stages of reclamation also occurs to the south of the stream, on McCauley Mountain.

For this reason, a 1997 report stated that this section of the stream offered poor recreational opportunities.

However, the report stated that the stream provided good recreational opportunities in its lower reaches.

[5] The upper reaches of the watershed of Scotch Run, upstream of Mifflin Cross Roads, are predominantly forested land.

[11] An ephemeral natural pool system is located in the vicinity of Scotch Run.

The forests and vernal pools on Scotch Run are fragmented by dirt roads.

[2] Scotch Run was entered into the Geographic Names Information System on August 2, 1979.

Some time before 1820, a carding mill was built by George Fleming on the stream southeast of Mainville.

[2] Scotch Run was surveyed by the Pennsylvania Fish and Boat Commission prior to the 1990s.

Two decades earlier, this part of the stream was also inhabited by pumpkinseeds and eastern blacknose dace, but not by brown trout.

[5] The lower reaches of Scotch Run were inhabited by eight species of fish in 1997: bluegills, brook trout, brown trout, blacknose dace, creek chubs, longnose dace, pumpkinseeds, white suckers.

The rainbow trout disappeared from the stream because the Pennsylvania Fish and Boat Commission stopped stocking them and the golden shiners were only present in the 1970s due to bait bucket introductions.

[5] The total biomass of wild trout in Scotch Run in its upper reaches is 2.98 kilograms per hectare.

[5] The total biomass of wild trout in Scotch Run in its lower reaches is 4.39 kilograms per hectare.

[5] Amphibians use the ephemeral natural pools on Scotch Run as a breeding ground.

Amphibians inhabiting the vernal pools on the stream include spring peepers, spotted salamanders, and wood frogs.

[9] A hemlock-mixed hardwood palustrine forest is present in the vicinity of Scotch Run east of the reservoir on the stream.

Other plants in the forest include teaberry, sphagnum moss, wood anemone, false hellebore, skunk cabbage, goldthread, and sensitive fern.

[9] The Columbia County Natural Areas Inventory recommends establishing a riparian buffer around Scotch Run and discouraging further development and all-terrain vehicle usage.