Water pollution in Canterbury in New Zealand has become a notable environmental issue due in a large part to the burgeoning dairy industry.
Water resources are under the jurisdiction of the Canterbury Regional Council (Ecan) under the Resource Management Act (RMA), and water abstraction and use for irrigation requires a resource consent. There is opposition to new irrigation schemes since they are seen to exacerbate water pollution.
The municipal water supply for Christchurch, sourced from the aquifers beneath the city, is untreated. This is unusual for a city of its size.
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Due to the rain shadow effect of the Southern Alps the rainfall in Canterbury is lower than many other parts of the country at 500–700 mm per year.[1] Water from melting snow and ice and from rainfall drain into the predominantly braided rivers on the Canterbury Plains. The rivers recharge the aquifers beneath the plains.
The Canterbury Region was traditionally arable and livestock farming but there have been a large number of dairy conversions in the region. In recent years there has been a huge expansion in dairy farming throughout the South Island.[2] Dairy farming requires the intensive use of water and it is placing a high demand on water resources in the Canterbury Region.
The rivers and groundwater are being polluted with nitrates and E. coli and proposed irrigation schemes can increase the pollution levels. Nitrate concentrations in the groundwater are above the drinking water standards in some areas and elevated levels are widespread. Indications are showing that the concentrations are rising. Inorganic nutrients, an indication of water quality, are considered to be low but increase closer to the coast. For 2000-2001 28% of tested sites were classed as "alert" due to the presence of organic pollutants.[3]
Water pollution of the two rivers flowing through the city of Christchurch, the Avon and the Heathcote, is of concern. Untreated sewerage can flow into the rivers during times of high rainfall. The estuary where the two rivers discharge had received treated water from the sewerage treatment plant that processed the city's sewerage. However, a pipeline was constructed to discharge the water into Pegasus Bay. It became operational in 2010.[4]
The Central Plains Water scheme is a large-scale proposal for water diversion, damming, reticulation and irrigation over an area of 60,000 ha. Other proposed schemes will irrigate an addition 90,000 ha.[3] A scheme to dam the Hurunui River to create water storage for irrigation attracted large scale opposition due in part to the possibility of increased water pollution. The resource consent application for the dams were put on hold.
A large number of resource consent applications for intensive dairy farming in the Mackenzie Basin attracted opposition due in part to the potential effects on water quality.[5] The resource consents were called in under the RMA by the Minister for the Environment Nick Smith.[6]
Cheviot has been on a boil water notice since October 2004.[7]
Dunsandel had an untreated water supply but in 2009 E. coli was found in the 70 metre deep well that supplies the town. Effluent from dairy cows is suspected to be the cause of the pollution.[8]
The Dairying and Clean Streams Accord was set up by Fonterra and a number of government agencies as a means of reducing nonpoint source pollution. The Accord is criticised for not achieving its goals.[9]
In recent years prosecutions have been made for causing water pollution: