Project Maitai / Mahitahi Newsletter Jan-Mar 2016
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Maitai Restoration Project

Tēnā koe

Community involvement in restoring urban waterways is both vital and difficult, as expressed so well by Ami Kennedy of the Friends of the Maitai below:

Everyone who lives here is responsible – we are all participating in creating the problem but there are not good mechanisms for getting involved in the solutions.” Ami Kennedy, March 2016

The Project Maitai/Mahitahi team and Friends of the Maitai have written a paper for the Stormwater Conference being held in Nelson in May about the project generally and the importance of community participation in urban waterway projects. The programme for the conference is here. It’s exciting to see the range of issues and solutions being discussed and addressed in this field.

Other key achievements for the Project Maitai/Mahitahi team in the January - March quarter have been the development of a board game based around the Maitai River, improvements to fish passage in the Brook and York Streams, completion of the toxic algae research projects for this year, and kicking off the design process for the proposed Groom Creek wetland.

We’re looking forward to planning the projects for next financial year, participating in Environment Week at the Elma Turner Library (28 May – 5 June 2016) and getting the riparian planting programme underway again for the winter, so please keep please your eyes open for updates on these topics over the next couple of months.

Read on for more detailed information about what’s been happening:

Project Updates

Almond Tree Flat ford

Fish Barriers Removed

Maitai/Mahitahi Ford Improvements

Almond Tree Flat ford is now the last remaining fish barrier on the Maitai River, so we have investigated a range of options to modify the ford to allow fish passage. None of the options were robust enough to withstand flood flows, and some of them could have an unexpected effect on downstream river behaviour. Therefore the recommended option for ensuring robust year round fish passage is to remove the ford. This option would not be expected to have an impact on the swimming holes downstream. We are currently surveying ford users for feedback on alternative options for access and we will run an online survey for the general public next month.
In the meantime, we are upgrading a portion of the Maitai track just below the golf course so that stock can use the bridge near the Maitai Camp and don’t need to cross the river at the ford.

Dogs Breakfast event

Less Toxic Algae Risk

Cyanobacteria Action Plan

A series of ‘dogs breakfast’ events were held next to the Maitai River to pass on information about toxic algae to dog owners. About 60 dogs and their owners were there and people even travelled in from Tasman to attend, so hopefully the word is getting out about the risks and what to look for. Remember the Maitai is generally safe to swim in (except after heavy rain), but dog owners and swimmers should know how to recognise toxic algae so they can keep away from it.

We’ve posted this video by Cawthron to our website to further educate people on what to look out for.

Cawthron research students in the Maitai River

Toxic algae experimental set up

The Cawthron research projects on toxic algae have been completed with some interesting results. Previous research has shown that slightly raised nitrogen, low phosphorus and stable periods of low flow provide good conditions for toxic algae blooms. Toxic algae has an advantage in low phosphorous conditions because it can extract phosphorous from sediment trapped in its mats.

This summer, toxic algae blooms (over 20% cover) were only recorded in the lower and mid reaches at Avon Terrace, Dennes Hole and the Maitai Camp, and only in November and December. The new research has noted that toxic algae blooms in the river could be affected by the blooms of other algae, in particular the green filamentous algae that bloomed strongly last year in spring. In low nitrate conditions it is likely they compete with each other for nutrients. In higher nitrate conditions it seems that the toxic algae is outcompeted by the green, so toxic algae blooms may be a result of biological activity as well as chemical and physical conditions.

The results also indicated that toxic algae blooms may be affected by unstable or variable river flows which though not strong enough to wash it all away, may disrupt the algal colonies.

Thanks to the Cawthron Institute, Dr Susie Wood and summer research students Alice Kilner and Dom Eardly from University of Birmingham in the UK for all their great work.

Paint at Collingwood St stormwater outfall

Clean Swimming Holes

Maitai/Mahitahi E. coli Source Identification

The image above is paint entering the Maitai River through the Collingwood St stormwater outfall. A painter working at a property near the Bridge St and Collingwood St intersection had washed his brushes over the stormwater sump in the carpark. If you see anything like this happening please let the Council know by phoning 546 0200 as soon as possible.

Monitoring for E. coli levels has continued at Collingwood St swimming hole with generally good results over the summer. Dye testing was carried out to look for any wastewater leaks in the area between Halifax, Bridge, Trafalgar and Collingwood Streets and no problems were found. We’ve completed one round of looking for E.coli in the Collingwood St stormwater system, and a second round is happening this week. The results will be used to look for cross connections between stormwater and wastewater systems to try and prevent E. coli from getting into the river in this way.

More Riverside Planting

Riparian Planting Project

The Friends of the Maitai have been doing wonderful things with their planting at Groom Creek and are intending to adopt the true left bank of the Maitai between Nile St bridge and Cloustons bridge. If you’d like to help, please contact them at, or go along to a plant care session at Groom Creek  every second Friday 4.30 – 6pm. Next one is April 29, then May 6 and May 20. Many thanks to the Friends of the Maitai for the sustained effort going into this planting which will be a piece of paradise in years to come.

Planning and ground preparation is underway for a big public planting at Little Brook Stream in the Brook Valley in August/September this year, in collaboration with the Nelson Nature programme. The stream is currently full of weeds and also suffers from sediment runoff from the cleared slopes above.

The planting plan developed in year one is being implemented, and contracts have been let for three riparian plantings around the golf course and Maitai camp section of the Maitai this winter.

Maitai Reservoir Spillway, credit: Anne Devlin

A Healthy and Natural River

Maitai Reservoir Operations

Last year we installed a 150m long spat rope and small pump at the Maitai Dam spillway – possibly the longest spat rope fish ladder in the country. The project team was unsure if it would prove too long, however spotlight surveys in February detected elvers using the spat rope to both aid climbing and as cover for resting. Although it was a long and arduous journey taking up to 5 days, some elvers successfully made it over the spillway crest and into the dam. Prior to this there was no fish passage over the spillway when it was dry.

A trial to change the way the Maitai Dam is operated is also underway, which means the dam won’t influence the Maitai South Branch at all for a 2-3 month period. We are monitoring it closely and looking for any changes in the health of the river.

Clearer Water

Groom Creek Wetland

The design process for the Groom Creek wetland is now underway with concept designs due in mid June. A number of outcomes are being sought from the wetland and associated amenity area including:

  1. A 20% reduction in annual load of sediment and nitrates entering the Maitai River via Groom Creek;
  2. Developing a model of good practice for others to follow in reducing the impacts of land development on freshwater ways;
  3. Establishing a model of collaboration between Council, community and commercial interests;
  4. Supporting an increase in biodiversity and habitat for native fish, birds, and other wildlife;
  5. Providing a site for environmental education via a boardwalk (or similar) with information and experiential learning;
  6. Further enhancing the general recreational values of the Maitai River.

Also on the subject of sediment reduction, a NIWA scientist who specialises in sediment source tracking was brought to Nelson as a collaborative effort with Tasman District Council through an Envirolink grant. The purpose was to present a new technique to staff and the public which allows identification of the source of fine sediment in rivers and estuaries. Thanks to Envirolink, Max Gibbs from NIWA, and the Nelson Science Society for hosting Max’s public presentation on the CSSI sediment source tracking technique.

Spat rope and baffles provide a fish ladder at the Brook historic dam

More Fish and Stream Critters

Aquatic Biodiversity Project

The image above shows a baffle and spat rope installed at the historic Brook Dam to provide a fish ladder. The baffle directs the water so the spat rope stays wet, and so long as the rope remains wet, climbing native fish species such as eels and koaro can climb up it. Non climbing species have to be transferred by hand with a trap and transfer system. These kinds of fish ladders have been installed in York Stream and at the Maitai Reservoir spillway, and planning is underway to install them throughout the Brook Stream too.

Members of Whakatu Rotary Club cleaning up Saltwater Creek

Litter Free Creek

Saltwater Creek Litter Management

The Whakatu Rotary group have done another clean up of Saltwater Creek and were delighted to spot both eels and inanga (whitebait) in the creek this time. Finding these species helps to reinforce that this is a creek rather than a drain, and once upon a time it would have been full of whitebait. The group was also pleased to report that there was less litter in the creek and no shopping trolleys! Thanks to the Whakatu Rotary Group and Nelmac for their on-going commitment to this project.

York Stream culvert at Victory Primary School

Fish-friendly York Stream

York Stream Fish Habitat

This photo was taken by students at Victory Primary School who are monitoring the state of the York Stream culvert and letting us know when the fish passage is blocked or the culvert needs to be cleaned.

Changes have also been made to improve the look and feel of the York Stream at Victory Primary School, including the removal of barbed wire from the stream fence, more frequent cleaning of the trash rack, installation of a fish ladder and planning for safe access to the stream so that students can do stream monitoring, riparian planting and litter clean ups. Students are also working on a project to help get the message out to the Victory community about caring for York Stream. Thanks to the staff and students at Victory Primary School for all their work on this project.

Fixing Saltwater Creek Pollution Sources

Saltwater Creek Water Quality

Visits have been made to all the industrial businesses in the Saltwater Creek catchment to discuss stormwater management practices, and the results have been very encouraging with an overall high level of awareness and good practice.

Saltwater Creek is buried under the footpath along Vanguard St and visits have also been made to residents in the catchment to find out what people know and remember about Saltwater Creek, and whether they are aware the stream is there. Some interesting stories are coming out, and one man even went swimming in the creek at high tide a couple of weeks ago near Vertical Limits!

Some sampling is planned in the next couple of weeks to check out the water and sediment quality, and we’ll also be doing a biological survey to see just what is living in the stream.

Enviroschools students playing Against the Flow at the Moturoa Mission event

Getting involved

The Maitai River now has its own board game! Against the Flow: the Maitai River Game is a bit like snakes and ladders except that you are a native fish trying to swim up the Maitai River and encountering good and bad experiences on the way. The game was made by the Friends of the Maitai, and then developed into event size and table size versions by a Project Maitai/Mahitahi working group. The huge floor version has been used at two events already, and the tabletop size plus a teacher resource will be distributed to Nelson schools to support freshwater education and celebrate World Environment Day on 5 June. There will also be a pull out version for everyone to play in the 15 June issue of Live Nelson, so keep an eye open for your copy. Thanks especially to Ali Kennedy, Jane Martin and Alison Horn from Friends of the Maitai, Mel McColgan (Waimaori Streamcare), Sterling Cathman (Mr Science), Lindsey Fish (Enviroschools), Glen Irain (Speedy Signs) and Megan Hodgson (Hothouse) for a real team effort.

If you’d like more information about something we’re doing or you have some feedback please check our website at or contact Jo Martin (Project Maitai/Mahitahi Programme Manager) on 545 8728 or

Copyright © 2016 Nelson City Council, All rights reserved.

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