My Account
Our streams get a hard time. A Council officer told me that somewhere between 100 and 200 kilometres of waterways lose their natural state each year across the Auckland region. They are replaced by pipes, turned into culverts or the earth is so moved about that there is no trace of them left. Streams are vital in managing stormwater run-off, maintaining water quality and sustaining biodiversity. I’ve seen a few eels in my time, but it was still a thrill to see a 600mm granddaddy lazing about in a pool of the Nukumea Stream. Our predominantly clay soils quickly colour up waterways in rain. The results are soon visible as they drain into the sea along with their sediment load.
The Okura marine reserve was seriously polluted during our wet winter from this cause. A half-moon of discoloured water stretches from Orewa beach to Red Beach after heavy rain as the tide empties the estuary. I swam in Sydney Harbour earlier this year, at Manly, and was amazed at the clarity of the water. I could see the rubbish lying on the bottom clearly! We don’t have the luxury of their rocky landscapes resisting erosion and so must rely on our waterways to filter out the dirt. This has long been recognised, but too often a mechanised solution is used rather than a natural one. Siltation ponds are appearing wherever new development takes place. Plantings on the edges are nice, but eventually the silt in them has to be dug out, exposing their artificiality.
Reserve contributions often go towards sports facilities, but a fresh approach to using this cash is being tried at D’Oyly reserve in Stanmore Bay. As reported in Hibiscus Matters earlier this year, a green sward atop a stormwater pipe is to be revived as a stream and wetland. It would be great if the culverted Red Beach stream could have the same treatment. What about a forgotten stream near you? Stanmore Bay stream, at the bottom of Arklow Lane, clings to life. Apart from a flow of water, nothing remains of it to suggest it is a natural place, unless you count the weeds. Bulldozed building platforms loom over it. Riparian margins around it and other streams need to be protected or re-established as development encroaches.
Rainwater quickly cascades into torrents that are hard to manage if it falls on impervious surfaces. But it seems footpaths are becoming wider and wider. At one time, 1.5m used to do; now they reach to three metres across, whether shared with bicycles or not. Concrete is still the favourite building material and the acreage of it ever rises.
Drainage infrastructure costs rise to match and landowners bear the cost.
Council monitoring optimistically labelled water quality on the Hibiscus Coast as ‘excellent’ overall, mainly it seems compared to chronically bad areas. The report noted that water quality declined to ‘moderate’ or ‘poor’ at sites in the upper reaches of the estuaries (Hibiscus Matters, November 16).
Given the pace of development we see every day, there is a challenge ahead to prevent a deterioration. But let’s make that a challenge for the ecologists to deliver us wetlands and streams we can be proud of rather than one for engineers to take up with concrete and plastic pipes.
