Project Maitai / Mahitahi Newsletter July-Dec 2015
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Maitai Restoration Project

Tēnā koe

The start of a new year seems like a great time to update you about progress on Project Maitai/Mahitahi for the last six months, as well as touch on what’s coming up.

Project Maitai/Mahitahi’s goal is ‘to work together to improve the health of the Maitai/Mahitahi river and its tributaries - so we can swim safely, collect kai, and value this taonga (treasure) as an integral part of Nelson’s physical and cultural landscape’.

There’s been lots happening at Nelson City Council to help meet this goal, and the Friends of the Maitai and our other partners have been busy too. See what’s been going on below.

The next 6 months is going to be busy too, with plans for: new riparian plantings in the lower and mid reaches of the Maitai; a big community planting in July; a request for feedback on options for the Almond Tree Flats ford; improvements to the York Stream area at Victory Primary School; visits to industrial businesses to look for ways to improve storm water management; improvements to fish passage barriers in the Brook and York Streams; and a great new board game called Against the Flow: the Maitai/Mahitahi River game. There’ll also be some results from the Cawthron cyanobacteria research and the reservoir operations project, and a draft plan for the Groom Creek wetland will be developed. If you have a special interest in any of these areas please let us know and we’ll make sure to keep you in the loop.

Project Updates

Recent fish passage improvements at the Waahi Taakaro ford

Fish Barriers Removed

Maitai/Mahitahi Ford Improvements

Our native fish need to be able migrate up and down our rivers to complete their life cycle, so obstructions like fords and culverts can really get in their way! The ford at the Waahi Taakaro golf course had a big drop on the downstream side of it which was difficult for fish to go past (see inset photo above). There were culverts underneath it but they blocked regularly and no fish could get past until they were cleared. So in early December we built up the level of the river downstream of the ford to remove the drop and hopefully our fish can now happily continue on their way. We’re currently working on the ford upstream of Sunday Hole, and also fish barriers in the Brook and York Streams.

Toxic algae on rocks appears black and oily

Less Toxic Algae Risk

Cyanobacteria Action Plan

This is the time of year when we get toxic algae (Phormidium) in the Maitai River and Brook Stream, and levels of many different kinds of algae have been high this summer. There are green filamentous and brown slippery types too, and these can be annoying but not poisonous. The toxic algae appears black and oily in colour – see the photo above. It’s still fine to swim in the river – but if you see toxic algae it’s best to keep dogs out of the water. Nelson City Council puts an alert on our website when levels of toxic algae are high – click on latest alerts at

This year Cawthron Institute scientists and summer students are running four research projects to help us understand what factors influence the toxic algae levels in the river. With more information we can plan to make conditions less favourable for the toxic algae!

Cawthron Institute also hosted a workshop for members of the Friends of the Maitai and local teachers to update everyone on toxic algae and other kinds of algae in the river.

Algae workshop at Cawthron Institute

Pollution entering the Maitai River from the Trafalgar Bridge stormwater outlet

Clean Swimming Holes

Maitai/Mahitahi E. coli Source Identification

We've been monitoring E.coli levels weekly in dry weather at low tide at four locations around the Collingwood St Bridge swimming hole since May 2015. We know there are often elevated E.coli levels in rivers and the sea after rain because of surface water run-off and leakage between the stormwater and wastewater systems. So we wanted to see if there is elevated E.coli in the river during dry weather and when there is no tidal influence. The results show generally low levels at the swimming hole which is great news. We also sampled the same locations at mid-tide for 6 weeks and found there were no tide-related increases in E.coli.

It's too soon to say it's consistently safe to swim in the Collingwood St swimming hole in dry weather because we still get some high readings, and we're trying to get the bottom of why this happens, but it's looking hopeful for the future!

In December we dye tested the wastewater systems throughout the area bordered by Collingwood, Trafalgar, Bridge and Halifax Streets and found no leakage into the river which is also great news.

The most important thing we can all do to keep the river swimmable is to make sure that only rain goes down the drains. The image above was taken in October by a member of the public who also reported it. It shows the effect of someone washing something out into a stormwater drain somewhere in the CBD. If you see anything you wouldn't want to swim in going down a stormwater drain please phone 546 0200 to report it.

Kiwi Conservation Club planting Ti Kouka (Cabbage Trees) at Sunday Hole.

More Riverside Planting

Riparian Planting Project

The Maitai planting project is full steam ahead and in the last 6 months there were plantings done at Maitai Camp, Groom Creek, Cloustons Bridge, York Stream at Victory School, Emano Reserve and Sunday Hole. There’s more planting planned for June and July, and priority areas have already been identified for the next two years. A huge thank you to all the individuals and groups who have donated time and energy to this project to date. Remember if your property backs onto the Maitai, Brook or York Streams or any of their tributaries, and you’d like to help shade the streams, please let us know! In most cases we can help with providing plants to be planted on the stream bank.

Nelson City Council and Tasman District Council scientists gauging the flow at the Maitai North Branch

A Healthy and Natural River

Maitai Reservoir Operations

We've been looking at ways to minimise the impact of the Maitai Dam on the Maitai River. In the last 6 months a flow meter has been installed in the Maitai North Branch to give us more accurate flow data for the river system, and we've been monitoring the fish passages put in place last year at the spillway and intake weir. Cawthron Institute has also provided us with a report about ways to improve the health of the reservoir itself through possible aeration. Most importantly officers and contractors have been planning a short trial to change the way the Maitai Dam is operated, which will mean the Dam doesn't influence the Maitai South Branch at all for a 3 month period. We'll be monitoring it closely and looking for any changes in the health of the river.

Proposed Groom Creek wetland area, on the true left of the Maitai River downstream of the Maitai Camp and the bridge.

Clearer Water

Groom Creek Wetland

In the past Groom Creek flowed into the Maitai River through a wetland before its path was diverted, and you can still see the residual wetland outlined in red on the image above. Monitoring at Groom Creek shows elevated nitrate levels and it contributes sediment to the main river after rainfall. Meetings have been held on site with consultants, Friends of the Maitai and Fish & Game to discuss the idea of restoring Groom Creek to its original path. The next stage is to put together a design brief, and, if all goes well, the diversion could happen in the next financial year.

The temporary sign installed at Pipers Reserve

More Fish and Stream Critters

Aquatic Biodiversity Project

Last year we were surprised and delighted to find a large population of Banded Kokopu (a type of native fish) in the small stream that starts in Pipers Reserve and runs down Emano Street. They probably swam up 3kms of pipe from Saltwater Creek to get there! We are working to improve the habitat there for them, and have installed temporary signs at the top and bottom of the track from Princes Drive to let people know about the work planned for Pipers Reserve.

Information brochure to help manage industrial stormwater

Fixing Saltwater Creek Pollution Sources

Saltwater Creek Water Quality

The Nelson Nature team have been working on all the Nelson urban streams not covered by Project Maitai/Mahitahi and have put together an informative brochure for industry to help manage stormwater and minimise impact on urban streams. If you know anyone who'd like a copy please let us know. We'll be visiting businesses in the Central City near Saltwater Creek and Tahunanui industrial areas over the coming few months to hand them out.

Members of Whakatu Rotary Club cleaning up Saltwater Creek

Litter Free Creek

Saltwater Creek Litter Management

Members of the Whakatu Rotary Club again donned their gumboots and gloves to clean up Saltwater Creek in November. During the clean-up we saw an eel and heard a story from a member of the public about the large number of fish that used to be in the stream. Many thanks to all who helped on the day!

Victory Primary School’s ‘Huriawa’ fence panel

Fish-friendly York Stream

York Stream Fish Habitat

Teachers and students at Victory Primary School have been busy learning about freshwater and the York Stream that flows through their school. They have created two beautiful freshwater inspired art panels to hang on the fence beside the stream, and have been talking to Nelson City Council about how to improve both the look and the health of the stream.

Students painting tuna (eels)

Friends of the Maitai education display at Cawthron Celebrate Science Fun Day at Victory Community Centre in November

Getting Involved

The Friends of the Maitai have active planting, monitoring, advocacy and education groups and there's always something going on – so if you'd like to get involved check out their webpage at

Here's a list of small actions everyone can take that will make a big difference:

  • wash your car at a commercial carwash or on a lawn
  • collect rainwater and conserve water over summer
  • pick up all pet waste so it doesn't get washed into the streams
  • adopt a drain and check that only rain goes into it
  • take part in a riparian planting project or plant your stream bank with eco-sourced natives
  • pick up litter to stop it being washed into streams.

It's amazing what can be achieved if everyone does their bit. Thank you to all the dedicated volunteers, scientists, teachers, and everyone who does what they can for our rivers and streams. We're looking forward to what can be achieved over the next 6 months.

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

Ngā mihi nui

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