Healing the Catchment
Words by Heather Johnson-Lee.
Photos by Benthics
Te Kohuroa awa (river) where the freshwater catchment meets the ocean.
Te Kohuroa Rewilding and the Mountains to Sea Conservation Trust shared a joint goal to improve the wellbeing of Matheson Bay’s freshwater catchment.
The ocean does not exist in isolation. What happens from the hills and down through the freshwater catchment has huge impacts on the marine environment. Pollutants that enter the ocean from land runoff, such as heavy metals and bacteria, can affect the wellbeing of the fish and other kai moana (sea food). Mud and sediment can also travel down stream and into the sea, clouding the water and reducing kelp photosynthesis by blocking light, and often deposits on the reef impacting invertebrate life.
Having multiple problems to solve that come from both the ocean and the land can make restoration processes more complex, so it's important to consider how they work together to impact the environment. This interconnected approach to ecosystem conservation is often referred to as a 'ki uta ki tai' – a mountains to sea process. So looking at freshwater conservation principles has become a key part of Te Kohuroa Rewilding’s project marine restoration goals.
“Mud and sediment can travel down stream and into the sea, clouding the water and reducing kelp photosynthesis by blocking light.”
Kelp fronds covered in sediment at Matheson Bay.
The Wai Connection.
After Te Kohuroa Rewilding was formed in 2024, the project team was introduced to Briar Broad, a freshwater ecologist and regional manager of the Wai Connection Programme through the Mountains to Sea Conservation Trust (MTSCT).
Through their Wai Connection programme, MTSCT engages with conservation organisations, farmers, landowners, and catchment groups all over New Zealand to empower communities by providing knowledge, tools and expert support to help solve issues in their local catchment. This seemed like an incredible opportunity for Te Kohuroa Rewilding to be a part of, so the team worked with Briar to find out if the project was be eligible.
After going through an initial evaluation process, Te Kohuroa Rewilding was selected for the Wai Connection programme and was matched with our very own MTSCT Catchment Coordinator. Hana Aickin (who holds a BSc in Ecology & Biodiversity) has worked in the ecological restoration and community engagement space for the past ten years so she was a perfect fit for the project’s goals. Hana began working with us to share ideas about what was possible for our catchment process, and how we could begin to engage and educate our community about its needs and wellbeing.
Through monthly planning meetings with Hana, our team started to create a roadmap to help our community understand what was living in our stream and the pressures around it. To fulfil our pilot project goal of learning more about the health of the awa (stream), we were also interested to learn about the water quality, the stressors that might be impacting the environment and also the freshwater life that was there. So we decided to take a more scientific approach to solving these problems by learning how to carry out regular freshwater monitoring.
Freshwater Coordinator Heather Johnson-Lee (left) and Andrew David (right) measuring water clarity at Kohuroa awa (river).
SHMAK Testing.
Over two days of workshops, a group of local volunteers worked through the SHMAK training process which stands for Stream Health and Monitoring Assessment Kit with the Wai Connection team, who also funded our testing kit. Over 20 years ago, this stream monitoring method was developed as a joint project between Federated Farmers and NIWA to provide land owners, iwi, schools and community groups with a simple scientifically-sound resource to monitor the ecological health of New Zealand’s streams. It was the perfect way for us to start to engage with the awa (stream) and learn about the state of its wellbeing.
The SHMAK testing process allows us to look at a number of indicators of the health of the Kohuroa awa (stream). These include:
Water Temperature and Conductivity
Water Clarity (measured using a 1 metre long clarity tube)
Nitrate and phosphate levels
E-Coli levels
Macro invertebrates (collecting and identifying stream bugs using a net)
An overall assessment of the habitat of the stream (stream bottom, bank stability, water flow, nearby vegetation)
Any impacts from upstream and surrounding land use.
What we’ve learned so far.
A beautiful short-fin tuna (eel) checking out the camera!
Since completing the training, we have completed testing in February, March and April at two different sites along the Kohuroa stream. Some of the interesting discoveries we have made are that our stream is home to a number of freshwater fish and eels (with some that have managed to climb up the main waterfall!) as well as different fly larvae, freshwater crayfish (kōura) and snails.
The macro invertebrates are very interesting because different bugs are more or less tolerant of environmental impacts so they are great indicators as to the health of our awa (stream). The fly larvae come in different shapes and sizes including stick-cased caddisflies that make their home in a bit of stick. You do not realise they are there until the stick starts moving! We have also discovered that the e-Coli (a bacteria linked to pollution) levels in the stream skyrocket after a period of rain.
Now that our community has a skilled group of volunteers who can monitor the wellbeing of the awa (stream), we plan to continue our monthly testing to understand the changes in our freshwater catchment over the seasons, and then move to quarterly monitoring in the long term. This will add valuable information to our catchment monitoring plan and help our wider community build knowledge that will guide our project objectives in the future.
“A stream is so much more than a place that moves water from the hills to the ocean, it is a whole world of living creatures that need our support to ensure they thrive and contribute to our natural environment that we live in and share.”
I have been surprised by the diversity of life in our stream and the habitats that exist there. Some of them have amazing stories to tell of international travel and waterfalls scaled - our plan is to support their extraordinary lives as best we can.
The SHMAK volunteers at the training session run by Mountains to Sea Conservation Trust at Kohuroa awa (stream).
About the Author
Heather Johnson-Lee is a Leigh resident and ocean swimmer. She became interested in Te Kohuroa Rewilding after learning about the project’s goals through the community. As well as volunteering in other parts of the project, Heather has undertaken TKRI’s Freshwater Coordinator role (funded by the Hauraki Gulf Conservation Trust) and is responsible for facilitating the freshwater work.