A new sewage outfall in Dunedin is now in use.
The water at Tomahawk Beach has been off limits for 100 years because of contamination from the old coastal outfall at Lawyer's Head.
The main swimming beaches, St Clair and St Kilda, have been closed for 12 and 15 days respectively this month alone.
Dunedin City Council says the new Tahuna outfall pumps sewage more than 1km out to sea. It has cost $37 million.
The council says the effluent will also be chlorinated in three months, which should eliminate any public health risk. It has undergone primary treatment.