Decided today to check out the Concord Unit of the Great Meadows National Wildlife Refuge. The refuge covers 3800 acres and stretches 12 miles along the Concord and Sudbury Rivers. About 85% of the refuge is covered in freshwater. The Concord Unit has about 3 miles of trails, but also connects to other trails if you want to extend your explorations. To get to the Concord Unit, drive to Monsen Road in Concord. At the end of the road you will see a sign for Great Meadows. You turn in at the sign and drive down a ways to the parking area. There are restrooms near the parking. The refuge is very popular for bird watching as well as walking. Currently, visiting the refuge is free, but they will be instituting a fee to help fund maintenance starting in the spring.
You can see lots of pictures on Flickr by clicking on the photo below: