Research report

Technical report

New Zealand’s fresh waters: values, state, trends and human impacts

12 Apr 2017
CREATORS

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Description

The report is in two sections. The first is a summary report written from my Office with the assistance of the Departmental Science Advisors from the Department of Conservation and the Ministry for the Environment. This overview avoids technical detail but tries to explain the core issues of public concern that have implications for policy development. The main body of the report is a more technical and scientifically referenced document that reviews the state of fresh water in New Zealand and issues related to restoration.

There are many measures of water quality – reflecting its physical, chemical and biological characteristics. However, no single measure is sufficient to understand the state of fresh water and the analysis is further complicated by gaps and inconsistency in the monitoring regimes. This is reflected in the current confusion over the proposed new water standards, which this paper seeks to explain. There is an inherent and pragmatic logic in having nuanced definitions that take into account what is an acceptable risk, consideration of the seasonal changes, the relationship to extreme weather events etc., but the impacts of such complexity must be interpreted and communicated clearly.

Water monitoring in New Zealand is imperfect, with sampling site distribution not fully representative of the environmental variation that occurs, sub-optimal site density in places, and variable quality of sampling and analysis protocols. Despite these challenges, the data very clearly shows that water quality and quantity is being adversely affected primarily by changes in land use and the diffuse contamination arising from pastoral farming and urbanisation. 

The report is intended primarily to inform the public and policy makers regarding the associated science rather than to point to specific policyinitiatives. There are clearly very complicated trade-offs between public expectations, economic drivers and recreational considerations in protecting our fresh water. This will require sustained commitment by governments, industry, local authorities and community groups, and an ongoing commitment to monitoring and research across multiple modalities. 

Key messages

Solutions to freshwater issues created by stressors are often complex but typically require three components – the availability of appropriate technologies and procedures (e.g., upgraded wastewater treatment, changes to urban or farm management, and mitigation systems); some form of policy intervention (e.g., rules and incentives); and societal pressure and commitment for change.

There are proven methods and technologies for minimising or reducing stresses imposed on fresh waters, including:

  • Protecting and restoring riparian zones and wetlands, and prioritising their protection in regional planning rules. This includes riparian planting and fencing to keep livestock out of waterways.
  • Ensuring water allocation does not exceed requirements for sustainable flow regimes in rivers. • Longitudinal monitoring regimes with the monitoring sites appropriate to the nature of the catchment and its likely issues.
  • Improving treatment of point source and diffuse source discharges and applying on-site and off-site mitigation tools to ensure that contaminant inputs do not exceed critical thresholds.
  • Using pest control technologies to reduce the abundance and spread of pest populations.
  • Retrofitting migration barriers to allow fish passage and developing alternative transfer methods.
  • Developing and expanding fisheries management for both native and exotic species.
  • Ensuring management and restoration efforts consider all stressors so that bottlenecks to improved ecosystem health are removed.
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PUBLICATION DETAILS

Peer Reviewed: 
No