Kaiwharawhara Catchment - Why you should give a Dam

In Wellington City, the Kaiwharawhara catchment is special – it's the biggest stream system, and it's the only one with an open estuary into  Wellington harbour. Nate Rigler, leading our Kia Mouriora te Kaiwharawhara Sanctuary to Sea project, reflects on the rich history of the Kaiwharawhara, shares the challenges it's facing, and reveals a powerful truth.  

Since beginning this role in August of last year, I’ve mastered pacing out the perfect 30-minute lunch time walk into the sanctuary from my desk. I like to take the route that hugs Roto Kawau and Te Māhanga Stream. I appreciate knowing that Roto Kawau, along with Roto Māhanga further into the valley, are headwaters of the Kaiwharawhara catchment—the largest subcatchment in Wellington and the only in our capital city with an open estuary connected to the harbour. As the new Project Lead for the Kia Mouriora te Kaiwharawhara Sanctuary to Sea initiative, this is something I think about quite a lot.  

I especially think about how the whaitua or catchment was once an abundant mahinga kai or resource gathering place. It was named by mana whenua, Taranaki Whānui te Upoko o te Ika, for the edible wharawhara plant (Astelia banksii) which would have towered above head in ancient podocarp forests. I imagine the shelter of these old growth forests during my exposed lunch walk through the valley. I take note of the species variation in the regenerative bush beside the track: mātai, kahikatea, rātā, rimu; none much taller than myself now but all with great ambition to grasp the sky. I spend a lot of time wondering what this landscape will look like in 500 years. 

While I’m aware that Zealandia is most popular for birds, I have come on this walk for fish. Since the removal of introduced Eurasion perch in 2021 there’s been an explosion of life here. Last year there were innumerable dragonflies. This year there are hundreds, if not thousands, of banded kōkopu. I make sure to allocate enough time on my walk to take a few minutes on the small boardwalk above Te Māhanga Stream. Here, I have learned, is the best location to observe young kōkopu fry swimming against the soft current. Of all the places I could go in the whaitua, this is the spot that I find most powerful. It’s here that I’m reminded that nature nurtures and enhances itself when given the opportunity. But that’s the key learning—it must be given the opportunity.   

Like so many other densely populated whaitua, the Kaiwharawhara is maimed by historic degradation and disrespect. Contaminated stormwater runoff, sewage leaks, invasive species, and piped stream through sealed landfill zones all tax the whaitua’s mouri or lifeforce. To be clear though, this isn’t to say that the problem is the presence of people in the whaitua. People are never innately the problem. This sort of thinking sabotages an optimistic approach necessary to instil positive environmental change. People have always had a place in their environment, and everyone has a part to play to ensure the health of the Kaiwharawahra. This is why Kia Mouriora te Kaiwharawhara Sanctuary to Sea was created—to heal the mouri of the Kaiwharawhara whaitua.  

This initiative was founded in 2017 in partnership with Taranaki Whānui te Upoko o te Ika, Department of Conservation, Wellington City Council, Greater Wellington Regional Council, CentrePort, Morphum Environmental Ltd, and GHD. Our vision for the catchment is clear: in 100 years, the whaitua will be a healthy freshwater and forested ecosystem in an urban setting, which sustains an abundant native biodiversity and enhances opportunities for Wellingtonians to have a nature-rich future. To be successful, we know that we need this work to be inherently collaborative. 

That’s why we work closely with local environmental groups and support their ongoing restoration projects. This is also why we have developed a network for businesses operating in the whaitua who are keen on taking nature positive steps in their workplaces. Every approach, big and small, is beneficial. Every action, gradually and collectively, enhances the mouri of the Kaiwharawhara.  

We know that long-term success of this initiative depends on the guidance of mana whenua, the support of national and local government, and the collective efforts of community groups and businesses. We are under no illusion that the work needed to restore the whaitua will be easy. But we have a powerful truth on our side—give people and nature the opportunity, and we will thrive.   

Photo: Project Lead of Kia Mouriora te Kaiwharawhara Sanctuary to Sea, Nate Rigler.