Ashburton Lakes

Forest and Bird, Issue 250, 1 November 1988, Page 25

Ashburton Lakes

by Dr

Ashburton branch councillor

Andy Bray,

he lakes and braided rivers of midCanterbury's high country are the home of an impressive number of birds belonging to twenty species of waterfowl, wetland and braided river specialists. In addition to the endangered southern crested grebe there are other notables such as the wrybill plover of which only about one thousand remain, and the self-introduced Australian coot. Probably the best known of the lakes is Lake Heron. Although the other lakes are familiar to few outsiders they are well used by anglers, yachties, power boaters and, to an increasing extent, by windsurfers. The lakes lie in a basin between the headwaters of the Rakaia and Rangitata rivers, two hours west of Christchurch by car. Since they lie in the bottom of a wide glaciated basin the lakes are shallow and have extensive wetlands on their margins. Distinctive Carex communities, bog rush and red tussock wetlands cover hundreds of hectares around the lake edges and along inlet and outlet streams. They are the home of marsh crake and bitterns and provide shelter from strong northwest winds for the waterfowl. One of the waterfowl that is not appreciated by farmers of the surrounding land is the Canada goose. These large game birds congregate in flocks of several hundred on the lakes and fly out to graze on pastures intended for sheep and cattle. Recreational hunters are unable to control their numbers so the local Acclimatisation Society undertakes culling operations to limit farm damage. Formal Protection Currently only Lake Heron and Maori Lakes have formal protection. Both are Nature Reserves and Wildlife Refuges. Ashburton people have been working for many years to get protection for the other lakes. Their efforts have been given impetus recently by the release of a Protected Natural Area survey of the region, and by inspections by the Nature Conservation Council and Aoraki National Parks and Reserves Board. Investigations by local Catchment Boards into the use of the lakes to store water for irrigation of the Canterbury plains has lent urgency to the matter. The Nature Conservation Council has long held an interest in the lakes and their wetlands, from the time of Sir Robert Falla who held their special values in high regard. The Parks and Reserve Board noted the "high wildlife, geological and scenic values and botanical associations that require protection." It has recommended to the Department of Conservation that most of the lakes and wetlands be designated Scenic Reserves, with provision for farming, access for recreationalists and management of fisheries, game birds and weeds. These recommendations are an important step forward. The ball is now clearly in the court of the Department of Conservation. Given the Department's public commitment that protection of the lakes will be

given high priority, the first concrete steps after nearly twenty years of discussions, meetings, inspections, submissions and recommendations can be expected soon. Increased Threats The need for speedy action arises from increased agricultural and recreational threats. Although the immediate threat of water storage for irrigation has receded, that posed by the development of the tussock grasslands and wetlands into pastures remains. Most of the lake’s catchments are at low altitudes so they have been cultivated or oversown with pasture grasses and clovers. Fertiliser application and increased numbers of sheep and cattle mean that more nutrients are now flowing into the

Jim Ackerley, Lynn Adams and Neville Adams were awarded Conservation Citations by the Nature Conservation Council for their outstanding work in protecting Ashburton’s high country lakes Hiss harmful development. Jim Ackerley has long been involved in bird conservation work, while Lynn Adams has got off to a flying start in conservation with her efforts on the lakes. A 7th former at Ashburton College, Lynn has been a guardian of the scaup and crested grebe on Lake Clearwater, ensuring that predators do not take eggs or chicks.

lakes. The loss of tussock cover and destruction of wetlands by cultivation, drainage and heavy grazing will result in more rapid run off of surface water and fewer nutrients will be trapped before reaching the lakes. Eutrophication will be favoured by the shallow nature of the lakes. Large scale pastoral development has taken place on Barossa station but the Grigg family have taken steps that will limit the impact on the lakes on their property. They have developed pastures all round the Maori Lakes but have fenced livestock out. Previously sheep and particularly cattle had grazed through the wetlands, right to the lake edge but now vegetation is regenerating in a substantial buffer zone. Mrs Phillipa Grigg expresses concern at the vigour with which introduced grasses and weeds are invading it and believes that light grazing might be better than none. Lake Emily is on the same property. Pastures around it have not been improved, nor have they been subjected to heavy grazing. In consequence the vegetation has been less modified than around other Ashburton lakes. Again the Griggs consider that continued light grazing may be the best way to maintain the site in its present condition. The condition of the lakes on Barossa and their wetlands can be contrasted with that of some others. In some instances land has been cultivated to the lake edge leaving no buffer strip, cattle have destroyed wetland margins and broken down stream and lake edges, and wetlands have been drained. It is hoped that not only will the Department of Conservation act to stop future actions of this type but they will also act on the recommendations of the Aoraki National Parks and Reserve Board for formal protection of the lakes.

Recreational uses also pose a threat to the natural values of the area. There is a shortage of water for power boating and windsurfing. Currently power boating is restricted to Lake Camp but it is overcrowded at peak times. Windsurfing has a rapidly growing following and windsurfers are looking beyond Lake Clearwater that they share with yachts. It has had a marked effect on bird numbers on Lake Clearwater. One of the reasons why Lynn and Neville

Adams and Jim Ackerley were awarded Conservation Citations was for their efforts to politely educate windsurfers and yachties as to the needs of the lake birds and the special charms of the crested grebe. They have found a ready acceptance of their views but their effectiveness depends on them being present and continued goodwill. They look forward to the formal protection of the lakes — their water, their wetlands and their wildlife.