The Billerica Trail is located in the Sudbury unit of the refuge. The trail is a walk around wetlands and through woodlands and features a non-motorized boat launch on the Sudbury River. 

The parking area for the Billerica Trail is on Nashua Road (MA-4) south of the Concord River bridge.

Just twenty miles west of Boston lies an oasis for wildlife, Great Meadows National Wildlife Refuge (NWR). Roughly 85 percent of the refuge’s more than 3,800 acres is comprised of valuable freshwater wetlands stretching along 12 miles of the Concord and Sudbury Rivers. The United States Fish and Wildlife Service protects and manages Great Meadows as nesting, resting, and feeding habitats for wildlife, with special emphasis on migratory birds. The diversity of plant and animal life visible from refuge trails provides visitors with excellent opportunities for wildlife viewing and nature study. A great diversity of birds has been recorded at Great Meadows NWR; an annotated list of over 220 species is available in a separate brochure.

In 1944, Samuel Hoar, a hunter, donated the first 250 acres of land that now makes up the refuge. The refuge now consists of two units of land in seven historically significant towns: Billerica, Bedford, Carlisle, Concord, Lincoln, Sudbury, and Wayland.

The refuge is open year-round from sunrise to sunset and has an entrance fee of $4 per vehicle or $2 per person. Pets and bicycles are not allowed on the trails, but restrooms are available at the parking lot.