Regional and district councils in New Zealand monitor water quality at hundreds of coastal and freshwater river and lake sites every summer.
If you are planning a holiday in one of New Zealand's other regions, check out the swimming water quality there on the following website:
http://www.mfe.govt.nz/state/reporting/recreational-water/local.html
The Ministry for the Environment has produced a national snap-shot report on the quality of recreational waters over recent summers in New Zealand.
http://www.mfe.govt.nz/state/reporting/recreational-water/snapshot.html