21 October 2011

Christchurch waterway ecology and health update following earthquakes

The character of many of Christchurch’s waterways has changed following the February 22 earthquake and aftershocks.

Immediately following February’s earthquake large volumes of untreated wastewater were discharged into the lower Avon River / Ōtākaro, the Heathcote River / Ōpāwaho, the Avon-Heathcote Estuary / Ihutai, and the sea.

The continued strain on the city’s infrastructure has meant untreated human sewage continues to be discharged into the lower Avon River / Ōtākaro, as well as Scarborough Beach.

Environment Canterbury and Christchurch City Council have been working closely with scientific and health organisations to monitor the public health status of the city’s rivers and estuary.

An up-to-date map of earthquake affected waterways is available online at: www.ecan.govt.nz/eq-effects-water.

The PDF map outlines the areas where contact with water should be avoided as well as summarising information on the scientific investigations and remediation work being carried out by Environment Canterbury and Christchurch City Council.

Research is ongoing to understand the state of city waterways as well as the ecological effects of wastewater discharges. This research includes: water quality testing; surveys of river fish, invertebrate and fish spawning; and testing of estuary shellfish. The research will allow informed decisions on a number of important issues including recreational water use and on-going wastewater discharges.

The advice from the Canterbury District Health Board (CDHB) is that contact with the two rivers, the Estuary/Ihutai and Scarborough Beach should be avoided. Bacteria and viruses in the water can cause serious illness (such as liver or kidney failure). Discharges are reducing in quantity but may continue for some months while the damaged infrastructure is being repaired.

The Christchurch City Council is sampling beaches adjacent to Christchurch from Waimairi Beach to Scarborough on a weekly basis. Environment Canterbury and Christchurch City Council are now also sampling sites within the Avon / Ōtākaro and Heathcote / Ōpāwaho rivers and in the Avon-Heathcote Estuary / Ihutai on a weekly basis.

Regular sampling has shown Waimairi, New Brighton, South Brighton, Sumner, and North Beaches are now safe for recreation. However, heavy rain can wash faecal matter into the sea, so people should avoid the beaches for two days after heavy rainfall. Contact with Scarborough Beach should be avoided as there is a discharge of raw sewage into the storm-water drain that empties into the sea.

Whitebaiters are advised that the Avon / Ōtākaro and Heathcote / Ōpāwaho rivers are closed for whitebaiting for the current season.

Environment Canterbury, Christchurch City Council and CDHB will continue to meet regularly to review urban water issues and provide information to the community.

ENDS

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