The water quality of the Waikato River is currently much better than it was in the 1950s. Major improvements in the treatment of the sewage and industrial wastewaters which are discharged to the river mean that levels of indicator bacteria in the lower reaches of the river are now many times lower than in the past. Eve so, conditions are still not suitable for swimming, and blue-green algal blooms occur at times. Non-point or diffuse sources of contaminants now dominate the nutrient and pathogens budgets. Progressively-intensifying farming, particularly in lowland areas, is thought to contribute the majority of the contaminants found in the river. Future improvements in water quality will therefore depend more on activities like changes to farming practice – such as retiring the riparian margins of lowland tributaries of the river – than on further advances in wastewater treatment.

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