John J. Kilmartin was a member of the Friends of Belle Isle Marsh who visited the Winthrop section of Belle Isle frequently. He observed material from the former dump at Fort Banks leaching into the marsh. John convinced residents and town officials to stop the erosion and funds were approved at the final town meeting. Belle Isle Marsh is now cleaner and safer for recreation and fishing.

The John J. Kilmartin Pathway is part of a larger plan for a Winthrop Greenway which will connect a route along Morton and Banks streets, the Belle Isle Cemetery, the Bayou and Argyle Street Marsh, over the new pedestrian bridge, and onto Short Beach.

The AllTrails website has a description and map of a hike using the John J. Kilmartin Pathway.