In 1860, the Hebron Marsh was farmland and pasture. The Ash Cottage was part of a large farm tract owned by the Crosby family. In 1935, this property was purchased by the Norton family. In 1979, Hope Norton Iaccaci donated the property in memory of her husband, Paul Thayer Iaccaci.

The Sanctuary includes 34 acres on both sides of North Shore Road and contains the only marsh on Newfound Lake. This wetland area was formed at the mouth of the Cockermouth River when the lake was dammed.