This 4.2 acre stretch of marsh and upland along Atlantic Avenue across from Sandy Beach was donated to the Trust in December 2012 by Susan Williams Dickie. Of the 4.2 acres, 16,613 square feet (.38 acres) is upland and the remaining square footage is salt marsh.
To the west of the property is a parcel of marsh and upland owned by the Sandy Beach Association. Together, these properties create a protected mixed salt marsh/upland that stretches from just before Sandy Beach to Nichols Road along the shores of Little Harbor.
In 2016, members of the Wakeman family who own property across Atlantic Avenue from Williams Salt Marsh, donated a .29 acre triangular wedge of land that extends from Atlantic Avenue into the Williams property.