I think any state forest lake, pond or stream.
I called the DCNR a few years ago about this and the answer I got was its considered just like primitive camping. If you want to camp in the same spot more than 1 night you need to get a permit.
Here is some info from the DCNR website.
"Primitive camping is available in all state forests except Cornplanter and Valley Forge. A permit from the district office is not required, but is strongly suggested for safety reasons. Some state forests have designated camping areas available for a fee. Call the district forest office for more information."
"Primitive Camping is defined as overnight camping where all equipment is transported in limited trips by non-motorized vehicle methods and where a motorized vehicle is not located near or part of the camping experience."
There is more info here..http://www.dcnr.state.pa.us/forestry/recreation/camping/index.htm
Google DCNR Primitive camping or backcountry camping and you'll find more info.