Mackenzie Basin - Environmental Issues

Environmental Issues

The original vegetation cover prior to human settlement has been completely transformed in the basin and indeed most of the surrounding Canterbury-Otago tussock grasslands ecoregion, initially due fires lit by Maori and European settlers, and in more recent times by farming activity and by pests. A relatively weakly settled area, in recent times (late 2000s), numerous proposals for new farming operations have locals fearing that the agriculture will be transformed from often family-held farms to large agribusiness operations causing increased local ecologic damage and siphoning off capital overseas. The effluent from proposed factory farming schemes, one proposed set of which would release sewage the equivalent of the city of Christchurch, is also feared to put further pressure on the ecosystems of local lakes and rivers. Over 5,000 submissions have been received in opposition to the dairy farming proposals, including from tourism associations, which fear that the industrial agriculture will damage the reputation of the area as well as its ecosystems.

The extensive network of canals for hydroelectric schemes posed a threat to the Black Stilt (or kaki), an endangered river wading bird. A captive breeding programme was set up and it is administered by the Department of Conservation.

The MacKenzie Basin is one of the areas where wilding conifers proliferate. These weed trees cover large areas sometimes to a very high density and therefore excluding native vegetation and reducing the amount of available pasture. Some areas have control measures in place to prevent the trees from spreading.

Rabbits are a common invasive species in the area affect both agricultural production and biodiversity. Rabbit numbers dropped after the introduction of rabbit haemorrhagic disease virus (RCD) but are now increasing. The Department of Conservation has plans to drop sodium fluoroacetate (1080) laced poison bait to control the rabbit numbers. This is seen as necessary due to the disproportionally high number of threatened plant species in the Mackenzie Basin. The plan attracted opposition at submission hearings.

There is currently a high demand for water to irrigate the MacKenzie Basin, with 126 resource consents from 36 applicants before Environment Canterbury as of mid 2009. The water would be used to irrigate an area of 27,125 hectares (67,030 acres), but the schemes are opposed by many locals and the Department of Conservation for the potential ecological effects, and since it may clash with a proposed MacKenzie Basin Drylands Park. Forest and Bird are also opposed to the irrigation for a variety of conservation reasons.