Scientific work investigates Christchurch waterway ecology and health following earthquake

Environment Canterbury and the Christchurch City Council (CCC) are working closely with scientific and health organisations to assess the earthquake’s effects on the ecology and public health status of the city’s rivers and the estuary.

Ken Taylor, Environment Canterbury’s Director of Investigations and Monitoring, said the earthquake had both direct and indirect impacts on Christchurch’s waterways.

“The physical characteristics of some of our waterways have been altered following February’s earthquake. Riverbed levels have changed and banks have collapsed, altering the alignment of channels. There have also been significant changes to the bed of the Avon-Heathcote Estuary/Ihutai.

“The discharge of sewage, trade waste and silt-laden stormwater into waterways has also resulted in physical changes to water and altered the water chemistry. This has impacted on the local ecology including vegetation, fish, invertebrates and micro-organisms,” he said.

Ken Taylor said the Council and Environment Canterbury have launched a joint significant study in conjunction with Ngai Tahu and Community & Public Health (CPH) which will help guide decisions on urban water issues.

“The ecological and microbiological studies of our waterways following February’s earthquake will enable informed decisions to be made on a number of important issues. These issues include recreational water use, and on-going wastewater and industrial wastewater discharges.”

Various types of research are being undertaken to help determine the current state of the waterways and the ecological effects of wastewater discharges and physical changes to waterways. This includes river water quality modelling, surveys of river fish, invertebrate and fish spawning, testing of estuary shellfish, water quality testing, an assessment of the height of the estuary seabed as well as surveys of the estuary habitat and ecosystem.

Environment Canterbury, CCC and CPH employees are meeting regularly to review urban water issues.

Up-to-date information on public waterways affected by sewage discharges can be found at www.ecan.govt.nz/services/online-services/monitoring.