Water quality tests at popular recreation spots in rivers and lakes around New Zealand show that many of them are unsafe for swimming.
The Ministry for the Environment has issued the results of testing by regional councils for e-Coli contamination.
Only 57% of the 206 freshwater swimming and recreation sites tested last summer were found to be safe for swimming most of the time. One in nine were often unsafe, due to high levels of faecal contamination.
A quarter of the hundreds of coastal sites also tested proved unsuitable for swimming.
The ministry says water quality at the monitored sites has changed little over seven years.
Monitored sites not typical - minister
Green Party co-leader Russel Norman says that industrial-scale dairy farming is responsible for much of the pollution and that the Government must take the lead and enforce water quality standards.
Environment Minister Nick Smith says however that the report exaggerates the situation, because the monitored sites are not typical.
Dr Smith says the Land and Water Forum set up last year is due to report next month on ways of dealing with water quality issues.