There’s a wealth in wetland diversity – don’t lose it, there’s both cultural and biological diversity in wetlands; and wetlands can work for you as well as be repaired.
The Waikato proved its environmental credentials on Sunday – World Wetland Day 2005 – when around 170 people turned up to celebrate the day and learn as much as they could about its themes this year.
As well as to celebrate the launch of Fish & Game NZ’s exclusive New Zealand Game Bird Habitat 2005 limited edition collectors’ stamp.
What was once an invisible event has grown enormously in popularity as worldwide the importance of fresh water – its increasing scarcity and conflict over use – has highlighted the role that wetlands play in sustaining water quality.
The event in the Waikato looked at the close links between people and wetlands, and how a good conservation wetland can also be an economic and recreational resource. It focused on restoration and rehabilitation – ways to do it and what a wetland can do for the landowner or industrial user.
Keith Thompson, wetland ecologist and the field trip’s leader, demonstrated that the most important factor in the success and sustainability of any wetland project is its hydrology. “If the hydrology isn’t right, the wetland won’t work. Moreover, you need to think long-term. Ecological changes are slow, so you have to know what you’re doing when you start your project,” said Thompson.
Andrew Hayes, a dairy farmer whose farm borders Lake Kaituna, demonstrated the success this approach can have.
By fencing off a one metre deep wetland, putting in silt traps and systematically removing pest species such as willow he had over several years transformed a weed-infested tangle into an attractive wetland with a maturing native vegetation, much enhanced bird numbers and increasing educational and tourism values.
“We used to have the cows in the wetland feeding off it and pooping in the water, and the Canada Geese and Mallards fouling our pasture,” said Hayes.
“Now we’ve got it the right way round, the cows are in the paddocks and the birds back in the wetland – there’s so much food for them they never cross the fence line.”
Hayes estimated it had been about 120 hours work a year for him to turn the wetland around, but the current result had only been achievable by working with DOC and Environment Waikato staff.
Kevin Hutchinson (Biodiversity Ranger, DOC) then showed how even such a shallow wetland could harbour a large range of pest fish species such as Koi Carp and Gambusia, as well as DOC’s solution to getting the balance of exotic and native fish species right – short and long-finned eels.
The other star turn of the field trip was Solid Energy whose two major Waikato environmental achievements - the Kimihia Wetland and Weavers Lake - demonstrated with could be achieved with wetland and water restoration on an industrial scale.
The Waikato is blessed with some of the ‘cleanest’ coals in the world (low concentrations of sulphur and heavy metals), but as Keith Thompson pointed out “coal mining is still a messy business, with two major environmental problems: disposal of contaminated water during mining operations, and rehabilitation of the land after the coal deposits have been mined out.”
Reuben Mills, Environmental Manager for Solid Energy at Huntly, discussed how Solid Energy had successfully addressed both of these problems by using wetlands to minimise water-borne contaminants, rehabilitate mine workings and reconstruct streams using sound ecological principles.
Huntly East Mine was established about 70 years ago. At first, it was of the open-cast type – just a hole in the ground – but it needed to dispose of the over-burden as the hole got deeper. To do this, the then State Coal Mines bunded off about one third of Lake Kimihia and the excavated over-burden was dumped onto what used to be the Kimihia lakebed.
Once the limits of excavation had been reached, coal mining operations went underground, where they are today. However, although there was no over-burden now, there was still a need to dispose of large quantities of water from the mine and from the coal washing operations.
The main contaminant is the very high load of suspended particles (very ‘dirty’ water). This is usually removed using an expensive chemical treatment to flocculate the particles, but at Kimihia it was decided to let natural processes remove the sediment. The old clay over-burden was levelled and coalmine waterwaters pumped out of the pit and discharged over it.
No planting was done, but over the years birds and the wind transported seeds into the disposal area and an 18ha wetland developed – each plant species establishing in the water depth to which is was best adapted. And as the plant communities established and became denser, the area became more and more effective in achieving its primary goal – removing sediment, lowering the pH and taking out some of the dissolved chemicals.
“If you compared the silt-laden water leaving the present Lake Kimihia (DOC), with it’s fringing pastures and lack of wetland protection, and the crystal-clear water joining from the Solid Energy Kimihia Wetland then you will see that water with 400 parts per million of sediment load could go in one end and when it came out five days later have less than four ppm of sediment,” said Mills.
Thompson reiterated this point: “Wetlands are extremely effective at removing silt and sediment, which is why the edges of streams and lakes should have wetland fringes to process agricultural runoff. “
Last stop was at Weavers Lake where, when the Weavers Mine ceased operation several years ago, there was simply a big hole with no purpose-built wetland to process the wastewaters. However, State Coal Mines eventually instituted extensive chemical processing of West Mine wastewaters and embarked upon a long-term programme of rehabilitating the nearby Lake Waahi where the wastewater was being disposed.
This project, linking the efforts of State Coal Mines/Solid Energy with local government agencies, iwi groups, the Department of Conservation, and local landowners, has involved techniques such as extensive riparian planting has created what is now an exciting recreational area.
“Eventually it will be a multi-use site, which is what the local community has continually told us it wants,” said Mills.
“We will have water skiing, yachting and aqua sports of all kinds happening here as well as a walking track around it.”
Already, thanks to a well-designed beach and water “bombing” area, it’s become an extremely popular swimming spot for local children.
The day’s festivities ended at the Rangiriri Garden Bar with a barbeque and the launch of Fish & Game NZ’s exclusive New Zealand Game Bird Habitat 2005 limited edition collectors’ stamp. Proceeds from the sale of this special stamp are used to fund the development and enhancement of New Zealand wetlands.
World Wetlands Day celebrates the signing of the International Convention on Wetlands in Ramsar, Iran in 1971. The Convention came into force in 1975 and New Zealand became a signatory in 1976. There are now 144 countries in the convention, this number increases as the realization of wetland importance grows.
Fish & Game NZ is the lead agency for the day’s events but it also provides an opportunity for a large number of agencies - DOC, Forest & Bird, the National Wetland Trust, Iwi, Regional Councils and corporate organizations such as Mighty River Power and Solid Energy – to come together and raise awareness about these often forgotten yet vital areas of water.
© Fish and Game New Zealand
"There's wealth in wetland diversity
- don't lose it!"