guideline water quality values for the protection of New Zealand river ecosystems and human health are recommended in the Australian and New Zealand Guidelines for Fresh and Marine Water Quality (Australian New Zealand ECC), and jointly by the Ministry for the Environment, and the Department of Health.
The median dissolved reactive phosphorus, oxidised nitrogen, ammonium, and E. coli concentrations in streams in pastoral and urban classifications of the study exceeded guidelines, and clarity did not meet the guideline.
The median E. coli concentration in native forest streams, and conductivity in plantaton forest streams exceeded guidelines.
The E. coli guideline was exceeded at every urban location, and dissolved reactive phosphorus, oxidised nitrogen, and ammonium guidelines were exceeded at 92, 86 and 83 percent of the sites respectively.
E. coli, dissolved reactive phosphorus, oxidised nitrogen, and ammonium guidelines were exceeded at 96, 88, 64 and 78 percent of the pastoral locations respectively.
The national median concentrations of phosphorus, oxidised nitrogen, ammonium, and E. coli of low-elevation streams in all land cover classes (urban, pastoral, native forest, plantation forest) combined, exceeded guidelines.
Dr Dell Hood, Waikato Medical Officer of Health, said the study shows that children should not swim in most of the country's lowland rivers.
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