Water pollution in New Zealand

[2] Fresh water quality is under pressure from agriculture, hydropower, urban development, pest invasions and climate change.

[5] In 2018, waterways across New Zealand have been showing improvements across a number of water quality measures, as monitored by LAWA data.

Since 2005 increased dairy farming rates of grazing animals have outstripped riparian planting and the ability of some Regional Councils to manage and mitigate impacts on the quality of water, and there is some evidence of urea use leading to nitrogen levels in waterways.

[4] In 2001 Fish and Game New Zealand started the high-profile dirty dairying campaign to highlight the effect of pollution from farming intensification on the ecological health of freshwater environments.

Fencing off streams and riparian planting has been shown to improve water quality, though this is more effective at reducing pollution from surface runoff (such as from phosphorus) rather than contaminants such as nitrogen which reach the waterway by seeping through the soil.

[11][12] Fencing prevent stock from depositing feces directly into waterways and trampling the banks; planting reduces surface runoff.

[13] Over the past decade, regional councils have increasing imposed more regulatory requirements on farmers to reduce their environmental impacts.

The plans require farmers to manage environmental risks around activities such as farm dairy effluent, erosion, discharges into waterways (through planting and fencing intensively stocked areas), irrigation and the application of nutrients.

[15] The changes to introduce stricter environmental controls on farmers have been cited as contributing to recent trends showing waterway improvements by Horizons Regional Council and Environment Canterbury.

In alpine areas, where anaerobic digestion of fecal matter is slow, the Department of Conservation have sewerage holding tanks on the toilets at backcountry huts.

Freedom camping, a popular activity in some areas, is suspected of causing water pollution due to the incorrect disposal of human waste.

[4] Urban areas have large amounts of paved surface therefore there is a higher likelihood that water contaminated with organic matter will not be filtered through soils.

These are completely inadequate in high rainfall events where the interceptors are overwhelmed and silt laden waters flow into streams and rivers.

In 2020, the National Policy Statement for Freshwater Management set safe "bottom line" levels for nitrogen, phosphorus, sediment and E. coli in New Zealand's rivers, lakes, and estuaries.

The Tarawera River, nicknamed "the black drain", has had a history of water pollution, predominantly due to industrial activity.

Remediation efforts on the canal (sparked initially by Ngāti Awa campaigner Joe Harawira) received international recognition in 2019.

[31] In 2019, Taranaki Regional Council reported that freshwater quality had deteriorated, with only two of the fifteen sites tested meeting the standards for swimmability.