Legal? Yes. There is public access through town owned land at the gas pipeline crossing at the intersection of Shangri La Boulevard and Blissful Lane. The access can be reached off Glen Charlie Road by taking Plymouth Avenue to Churbuck Street to Sunset Boulevard. Parking is limited and boat launching is limited to canoes and cartop boats. Other nearby ponds are Agawam Mill Pond, Halfway Pond, Spectacle Pond (Wareham) and White Island Pond. Info from mass.gov
There is also a small launch area on Agawam Road, by the creek channel that leads to that small reservoir.