Greymouth Preston Rd and Johnson St Wastewater Treatment Plant, Grey District, New Zealand

Greymouth Preston Rd and Johnson St is an advanced wastewater treatment plant located in the Grey District on the West Coast of New Zealand's South Island. The facility serves a population of 4,071 and discharges approximately 953.64 megaliters of treated wastewater annually. The plant employs advanced treatment processes, which go beyond secondary treatment to remove nutrients and other contaminants. Under New Zealand's Resource Management Act, such facilities must meet strict discharge standards to protect receiving environments. The plant's coastal location places it under additional scrutiny to minimize marine impacts. The treated effluent is discharged into the Tasman Sea via the Grey River or nearby coastal waters. The West Coast region is known for its rugged natural environment, and the plant plays a key role in protecting downstream ecosystems, including estuarine habitats and marine life.

The plant discharges into the Grey River, which flows into the Tasman Sea near Greymouth. The coastal environment supports diverse marine species and is an important area for local fisheries. The advanced treatment helps reduce nutrient loading and protects the sensitive estuarine and nearshore ecosystems from eutrophication and contamination.