Westhaven is the first estuary in New Zealand to be protected by a combination of marine and wildlife reserve, with the creation of the Westhaven-Te Tai Tapu Marine Reserve and Westhaven (Whanganui Inlet) Wildlife Management Reserve. The reserves were established in 1994.
The marine reserve covers 536 hectares and includes all the tidal sandflats and channels south of a straight line between Melbourne Point (Pah Point) and the closest headland of Westhaven Scenic Reserve. It also includes all the tidal areas upstream of causeways along Dry Road, southwest of and including the Wairoa River. An area around the Mangarakau wharf is not included in either reserve.
The reserve totally protects all plant and animal life within its boundaries, benefiting not only fish and shellfish, but birdlife as well.