I grew up in Cumberland. It's a mix of land owned by the Pawtucket water supply board (long story on that one, Cumberland sold off alot of it's reservoirs/streams to Pawtucket back in the day ), National Grid (or whatever group they are now), and private landowners.

It's a former railbed of the defunct New York and New Haven railroad that National Grid bought and used as an easement to run gas lines through.

Some people walk on it, but National Grid does have security planes do flyovers of the land, and the city of Pawtucket does have security trucks drive around the area.