Simonson Brook starts at 40°24′58″N 74°35′29″W / 40.41611°N 74.59139°W / 40.41611; -74.59139,[1] in southwestern Franklin Park near Route 27.

It runs through two housing developments then runs into the woods and flows near Bunker Hill Road, passing through the Bunker Hill Environmental Center and the Griggstown Native Grassland Preserve.

Simonson Brook can be accessed by trails in the Griggstown Native Grassland Preserve, part of the Ten Mile Run Greenway.

This stream is very rocky near its mouth, with broken slate covering the streambed.

It is fed by periodic springs, making it dry up very easily when it is not raining.