Persistent rain overnight and into this morning has seen Avon River levels rise in the city centre, breaching its banks in some places.
The Whale Watch operation was temporarily forced out of business after the 7.8 earthquake, but is now back in operation.
Scientists will begin testing wastewater from communities across New Zealand to find hotbeds of P, heroin, cocaine, ecstacy and bath salts.
Up to 900 former and current construction and manufacturing workers die from breathing in airborne contaminants each year.
Healthy adults in the Southern DHB and Counties-Manukau DHB regions will be the next to benefit from the nationwide screening programme.