The site is an exceptional freshwater marsh. It preserves habitat for two rare bird species that frequent the area. The marsh preserves the habitat requirements of numerous bird species, including waterfowl. The site is a 540-acre freshwater marsh dominated by cattails, with sedges, grasses, and rushes.
Higher ground has cottonwood, red maple, red oak, and alder.
The Saugus River flows through the site. Dredging and filling of the wetlands adjacent to the NNL boundary for construction has occurred. There are subsequent increases in anthropogenic inputs into the marsh from development such as toxic run-off from parking lots and golf courses, fecal bacteria, and nutrient inputs. The site is progressively becoming a habitat island in the midst of surrounding urban development. The marsh is bordered by much large-scale development such as an industrial park, hotel, and others.