Deerlick Run starts in northern Mount Pleasant Township, near the community of Welliversville.

It flows southeast for a number of miles in a fairly shallow valley to the eastern part of Mount Pleasant Township.

[4] Deerlick Run experiences significant levels of siltation and stream bank erosion.

The erosion coefficient of Deerlick Run ranges from 0.12 between September and March to 0.3 during the rest of the year.

No part of the stream or any of its tributaries attains the water quality standards of the Pennsylvania Department of Environmental Protection.

20 percent of the surface rock is sandstone The dominant hydrologic soil groups in the Deerlick Run watershed are C (90%) and B (10%).

4.0 percent of the land is designated by the Pennsylvania Department of Environmental Protection as "low-intensity development".

9.9 acres of land in the watershed are classified as "transitional" by the Pennsylvania Department of Environmental Protection.

[1] Deerlick Run is designated as a coldwater fishery because it can support fish species of the family Salmonidae.