Date: Wed, 3 Mar 2021
Waitarakao / Washdyke Lagoon is a coastal lake separated from the sea by a long stretch of mixed sand and gravel sediment, surrounded by State Highway 1, the meat works and the Washdyke industrial area.
Its importance stems from native ecological habitats, biodiversity, cultural and historical values.
For the longest time it had the perfect mix of saltwater and freshwater, allowing a diverse range of native species to thrive there.
On this page:
- A history lesson
- Grant's first memories of the lagoon
- A home for precious native species
- The lagoon then and now
- A solution?
- Future steps
First, a history lesson
However, over a period of more than 100 years the lagoon has deteriorated. European settlers hugely influenced its fate when they chose to build a breakwater, port, and industrial area right on its doorstep. The presence of SH1 and the main railway line restrict the lagoon’s ability to migrate landward. Those barriers prevent the lagoon from expanding, while the sea pushes the gravel barrier ever inland.
These influences, among others, have resulted in the lagoon shrinking from about 250 hectares in 1881 to less than 10 per cent of that today. Preserving the balance between fresh and salt water is important as, without it, some species do not have the right conditions to live there.
The gravel barrier beach between tide and lagoon is believed to have retreated about 400m between 1865 and 1987 and is continuing to retreat today. This is due to the breakwater – built to service the Port of Timaru – halting the natural movement of shingle and coarse sediment from rivers to the south, moved north by swift currents off the Canterbury Bight.
The coarse sediments that would be dumped onto Washdyke Barrier, protecting the lagoon from erosion, can no longer reach the barrier. It now hits the breakwater and builds up on South Beach at Timaru, while the finer sands wash ashore into Caroline Bay, causing both areas to grow seaward. Further north, the interruption in sediment movement has starved the coast and rapidly diminished the size of the lagoon.
A similar case was seen to the north of the lagoon in Waimataitai Bay, which has disappeared entirely since the breakwater and port were built. The barrier enclosing the lagoon rapidly eroded after construction, destroying the lagoon and leaving an open bay in its place.
Grant's first memories of the lagoon
George ‘Grant’ Ward grew up in Timaru and has been involved with Waitarakao on and off for more than 70 years. The octogenarian invited Environment Canterbury out to the lagoon recently to recount his story and discuss how the community can help protect and enhance Waitarakao into the future.
“I began whitebaiting at the mouth of the lagoon in 1948 when I would’ve been nine or 10 years-old. We whitebaited there for a long time quite happily as kids and when I came back to the lagoon later in life, the flow of the lagoon had completely changed.
“The beach 70 years ago was three, if not four, times smaller than it is today – it was just a tiny strip separating the lagoon from the sea. It started off a really pristine waterbody and I remember the water being quite clear and transparent as a kid. Now it’s a horrid green colour.
“I picnicked with Mum and my brother between the months of September and January. We’d get off the bus and head down to the lagoon. In September there was a small whitebaiting fraternity, maybe a dozen or so of us, but we’d end up catching a half dozen whitebait for a patty and head home.
“The water always seemed to be clear, there was always shrimp and whitebait in it. We’d catch a handful or so and Mum would spread it out between a large patty and divide it up amongst us,” Grant said.
A home for precious native species
“Mum was an active member of Forest and Bird and we travelled to the lagoon regularly to spot dotterels, oyster catchers. There was a Caspian tern colony and black swans too. I remember the pied stilts would have their nests right near the lagoon mouth and they’d be quite happy for you to sit and whitebait just a few metres away.
“I remember mum, my brother and I bird watching, checking out the bird nests. My brother and his friend used to catch eels in the creek too – they’d just put their hand in the water and grab them out – you couldn’t do that nowadays.
“My main memories, standing here now, are walking down the beach with black swans nesting in the marram grass there; somewhere in the vicinity was a Caspian tern colony, and right at the mouth of the lagoon was a colony of pied stilts.
“They were there for two or three years, quite happy, and nesting only two or three metres from where we were whitebaiting. There were banded dotterels and perhaps wrybills, but as a child I doubt I would’ve been able to pick out a dotterel like I can now,” Grant said.
The lagoon then and now
“Now, nature has increased the size of the beach – sure. But now the lagoon also has to compete with the huge needs of the Washdyke industrial area, which has delivered untreated stormwater to the area.
“We are now looking at a lagoon which is about 20 hectares in size. It was at one point 250 ha. Today, I walked down and I couldn’t get over the increase in the size of the beach. The beach to the lagoon now is four times the width it was when I was a child.
“The beach now seems to have much more growth on it – much more marram grass. As I’ve grown up I’ve seen huge changes in the environment and the commercialisation of our natural species.
“When I think of that I think of the tremendous effect we’ve had on the eel population. The eel population was absolutely abundant as a child. Now, you get into the water and it is difficult to find an eel. The same thing applies to water. We are over-utilising our water resource,” he said.
A solution?
“The simple solution, in my eyes, is to increase the surface area of the water back to how it was – to at least give the lagoon a chance to flush out some of the toxins, the waste and the run-off that are being pumped into it.
“Nature has done something to increase the beach because of our Timaru harbour and that has diminished the lagoon. But on the other hand, when I was a kid there was just three buildings in the Washdyke industrial area – the Doncaster Hotel, a garage, and a little shop. Look at it now. And we expect the environment here to deal with that?
“And even though we do the best we can with things like the sewerage quality improving, when you take water away, nature can’t deal with it. What we’ve done here is decrease the water area.
There was 250 ha of water here – now there’s 20 and Environment Canterbury is asking ‘what can we do about it?’ Well, I’ll tell you the first thing they need to do is they need to increase the amount of water getting into the lagoon.
“Somewhere along the line, according to me, you’ve got to give back to the lagoon. And it’s got to be the people who are responsible for all this – the industrial area. Hopefully if you do that, you will attract the species I saw as a child come back to this lagoon. To see them back here with the water quality back to how it was, would be an absolutely marvellous thing – and I think it can be achieved relatively easily.
“In summary, the lagoon in 1950 was clean, the water was clear. The build-up of the shingle beach had not affected the out and in flow of water to the sea. Looking back, a healthy water level and volume was maintained. Since then, the industrial area has sprung up, a sewage pipeline has been installed, a channel and drainage system has been installed – removing surface water area and volume – and input from elsewhere is minimal,” he said.
Future steps
Environment Canterbury is one of several organisations involved in planning for the future of Washdyke Waitarakao Lagoon. We are working with others to understand, research and plan what improvements are needed to support Washdyke Waitarakao Lagoon environment for the betterment of the community.