Once, virtually the entire Commonwealth of Massachusetts was home to brook trout.  Today, they have been virtually extirpated from the greater Boston area.  Other habitat is degraded, though there are a fair number of good brook trout streams in the far west of the state, particularly in the Hudson, Westfield, and Deerfield drainages.

Source: Eastern Brook Trout Joint Venture, Google Earth

The photo above shows the brook trout habitat dataset published by the Eastern Brook Trout Joint Venture, displayed in Google Earth.  You can download the complete dataset in KMZ form, which can be used as part of your own Wild Trout workstation.  If you don't use Google Earth (a decision you may wish to reconsider), you can download a detailed map based on an earlier version of this dataset.  Both are available in the "MA Resources" menu in the sidebar.  The color coding in the photo is as follows (from best to worst)...

• Blue
  
• Green
  
• Yellow
  
• Orange
• Red
  

Keep in mind that brook trout can be diminished by other trout species, so some red areas may be excellent wild brown or rainbow water.  But it's almost certain that the yellow and better areas are great places to find wild trout.  Areas not surrounded by a colored line don't hold brook trout at all, though migh hold other species which are more tolerant of warmer water (see species distribution maps).