Osmun Forest Natural Area
Knowlton Township, Warren County, NJ
Management Objective: preservation of a northeastern mixed hardwood forest
Interim Classification: ecological reserve
Administering Agency: Division of Parks and Forestry, through Jenny Jump State Forest
(Source: http://www.state.nj.us/dep/enforcement/relprev/dpcc/document/esaguide.htm)
There is an Osmun Road near the southern end of Honey Run Wildlife Management Area, which might be the location of the place. I will have to check it out.