River and stream health

Overall the 2015 annual water quality class for each site has reflected the long term trend. 73% of monitoring sites were classified at grade C or above, a slight improvement compared to their classifications reported in the Nelson Plan (2007). Nelson waterways were significantly impacted by the 2011 flood and are now recovering from subsequent instream flood maintenance works. Stoke also experienced a flood event in 2013, resulting in further erosion and surface run off and disturbance to stream beds and their aquatic communities. 

Why we monitor water quality and ecosystem health

Rivers and streams have important natural and cultural values. They are also important resources for drinking water, farming, recreational activities, managing storm water and industrial use. Human activities and discharges to rivers from various sources affect the quality of water and its suitability for human use and biodiversity.

Toxic Algae Cyanobacteria

Toxic algae (also known as Cyanobacteria) is naturally present in many New Zealand waterways. It's found in ‘clean’ rivers but can grow when river flows are low and stable, and temperatures are consistently warm. Council routinely monitors its level and informs the community when action needs to be taken. Learn more in the Toxic Algae section.

How we classify Nelson’s water quality

Nelson’s streams and rivers are classified from grades A to E (Excellent to Very Degraded) based on regular water quality and stream sediment monitoring across 28 sites. A long term water classification has been derived from monitoring data collected from 2000 to 2012. The long term classification provides a ‘bench mark’ and better indicator of the health of our rivers and streams than annual results as it reduces the influences of short term events, such as floods.

Trends in water quality

Biodiversity fish surveys

Wade-able fish surveys were undertaken on the Brook Stream and lower Maitai at river ecology sites. Koaro were abundant at the Waimarama Sanctuary, indicating fish passage work on the Manuka Street weir and culvert in 2006, and ongoing maintenance have been successful.

Smelt and brown trout were also recorded upstream of the concrete box culvert, indicating some fish passage. A high diversity of 14 fish species were present in the lower Maitai at Riverside, reflecting the good connectivity to the Haven estuary and Tasman Bay.

Annual monitoring summary

The annual monitoring summary reports on the health of Nelson's rivers and streams, tracking whether the health of these waterways is getting better or worse. It also identifies particular issues and what might be causing the degrading of our rivers or streams.

Annual Monitoring Summaries

What are we doing about it - Initiatives to improve water quality

Working with land owners

Nelson City Council provides free advice for land owners and financial assistance toward fencing livestock out from waterways and native plants for riparian planting and biodiversity enhancement. Several residents have taken up the offer of Council assistance to fence and plant along the Lud, Wakapuaka River and Stoke streams.

Initiatives to improve water quality

The Friends of the Maitai community group was established in 2013. The group promotes a collaborative responsibility for the health of our waterways and gives community members a gathering place to learn about the issues that face our river and work together to take positive action. For more information about Friends of the Maitai contact friendsofmaitai@gmail.com.

The Waimaori Streamcare Programme works with schools and local people to actively monitor the health of streams through practical hands-on-workshops at the riverside. This raises community awareness about water quality and also brings a cultural perspective as to why clean water matters. For more information about Waimaori contact waimaori@ncc.govt.nz.

Council is collaborating with NIWA, the Friends of the Maitai and the Wakapuaka River Care Group to trial a new community stream monitoring programme. The NIWA led citizen science project will assess whether community monitoring data can be used alongside regional council water quality monitoring and add value to the national environmental picture. For more information about NIWA’s community monitoring projects, visit www.niwa.co.nz.

Project Maitai/Mahitahi has an overarching goal to create a river that is safe to swim in and take kai from. The integrated projects are addressing a range of issues affecting water quality. For more information email Jo.Martin@ncc.govt.nz or visit the Project Maitai web page

Council will be working with community groups to discuss values and water uses as part of the process to establish Fresh Water Management Units and monitoring requirements under the National Policy Statement for Freshwater Management.

NCC work in progress

  • Enhancement of riparian margins and instream habitat for wildlife in urban streams, as part of the flood recovery remediation work.
  • Working with local Iwi to improve the well being of the Nelson environment through site assessments using Iwi Cultural Health Indicators, building stronger relationships and targeting actions.
  • Working with Tasman District Council to identify and improve whitebait spawning habitat and establish a network of native fish monitoring sites across the region.
  • Working with Landcare Research to characterise river behaviour to achieve better gravel management and erosion control in North Nelson.
  • Working with NIWA to evaluate the most appropriate technical solutions to improve existing storm water systems and minimise contaminants from roads and adjoining land reaching rivers and streams.
  • Working with Cawthron to study the water quality from the bottom of the Maitai Dam and how its discharge to the Maitai impacts on the aquatic animal and plant communities and how this can be reduced.
  • Working with other regional councils and local government to share national water quality trends on the Land and Water web portal. For more information see http://www.landandwater.co.nz/
  • Review of the long term water quality classification for each monitoring site, incorporating data from 2000 to 2012.
  • Facilitating and supporting environmental education through primary school to college utilising Nelson City Council monitoring results.
  • Investigating bacteria contamination in lower Maitai from the storm water system, and potential cross-connections in other Nelson urban areas.
  • Working closely with the District Health Board Health Protection Officers and Cawthron to find more effective ways to reduce the potential public risk of toxic blue green algae in our waterways.

Wakapuaka River Temperature Survey

The Nelson City Council environmental monitoring has shown a decline in the overall water quality grades of the mid Wakapuaka and Lud River since 2007. This is summarised in the River and Stream Health Annual Monitoring Summary 2011.

Below is a summary of a survey of the latest summer water temperatures. The warmer temperatures are harmful to our waterways, their resident fish and invertebrate habitat, as well as affecting initiatives to improve water quality.

Download the Wakapuaka River Water Temperature Survey 2009 / 11 (264KB PDF)

Wakapuaka and Whangamoa Rivers Gravel Management

Landcare Research was commissioned by Council to provide advice on managing gravel resources for the Wakapuaka and Whangamoa rivers. The project was funded by a government Envirolink grant, resulting in river cross-section surveys being undertaken each year. The monitoring programme has been reviewed including an assessment of changes over a ten year period, using aerial photography. Whilst gravel extraction volumes appear to have been relatively low for both rivers, the report highlights the need to improve the process for managing resource consent information and highlights areas of gravel aggradation and erosion important for assessing future consents and river protection works.

Download the Wakapuaka and Whangamoa Rivers Gravel Management Report (1.1MB PDF)

Nelson Freshwater Quality Classification

Nelson’s freshwater quality classification and river health monitoring information has been independently reviewed, providing a stock take of Nelson freshwater quality and the significant freshwater trends from 10 years of monitoring. The report also incorporates trend analysis for the first time, assessing the affects of season and river flow on measured nutrient loads. The report is timely, given the information requests and proposed national reforms to land and water management. Overall, there has been a slight improvement in water quality at monitoring sites. The recommendations in the report include investigations to identify pollution sources in the York and Poorman Valley streams and Maitai catchment, which will be part of the environmental monitoring work programme over the next year. 

Download the Updated Freshwater Classification for Nelson, 2013 Report (2.4MB PDF)

Maitai Catchment reporting and status

Nelson City Council has commissioned the Cawthron Institute to undertake a series of studies to assess the status of the Maitai Reservoir in terms of providing for the functioning and ecological health of the Maitai Catchment. Information from these reports will contribute toward the re-consenting process of the Maitai Reservoir and South Branch water takes, due in 2017.

Download the Maitai Reservoir and North Branch Habitat Survey (1.3MB PDF)
Download the Impact of the Maitai Dam on the River Health Relative to Other Catchment Pressures (573KB PDF)

Freshwater monitoring website

The LAWA website has water quality data from New Zealand’s freshwater monitoring sites is now available. The Land, Air, Water Aotearoa (LAWA) website is a collaboration between New Zealand’s 16 regional and unitary councils, the Ministry for the Environment (MFE), Cawthron Institute and Massey University. 

Fish review and distribution maps 

This report provides a summary of the freshwater fish species and their known distributions within the jurisdiction of the Nelson City Council (NCC). Records of fish species (including freshwater crayfish) have been taken predominantly from The National Institute of Water and Atmospheric Research (NIWA) freshwater fish database (FFDB) and are current to December 2014.

Please contact the NCC Environmental Programmes team at paul.fisher@ncc.govt.nz or 03 546 0200 for further information about freshwater fish species and opportunities to participate with fish surveys and stream restoration projects.


Distribution and spawning of freshwater fish within the waterways administered by the NCC (555KB PDF)

Freshwater fish sightings webmap

The web map shows the distribution of native fish for Nelson region. It will be updated every year. Freshwater Fish Sightings WebMap.