Here's my take on this, based on spending about 20 minutes in the Law/Regulation booklet.
1. It looks like no salmon over 25" may be taken in any brook, river, or stream.
2. Look up the name of any lake or pond you wish to fish. If it shows an S-33 regulation exists on that body of water, then you can't take a salmon over 25" there. All other lakes and ponds appear to allow you to take a salmon over 25". The type of lake where there may be an S-33 is a lake within an Atlantic salmon run of some magnitude. Examples in eastern Maine are Beddington Lake in the Narraguagus watershed, all of the Machias Lakes (1st through 5th), Old Stream Lakes, 1st - 3d Chain Lakes in the Machias watershed, Hadley Lake, Second Hadley Lake, Round Lake, Crawford Lake in the East Machias watershed.
This is not a complete and perfect list, but is intended to try to clarify the matters. Please remember I don't work for IFW any more -- retired 6 years ago, so was not involved in this lawbook.
Salty