Estuary health check

Estuary health check

Scientists from NIWA and Canterbury University are developing a diagnostic toolkit to assess the health of the Avon-Heathcote Estuary before and after a new wastewater outfall is installed.

Treated wastewater has been discharged into the estuary for about 40 years. The high levels of nutrients it contains may be responsible for problem blooms of sea lettuce in summer. Local authorities have commissioned an outfall to take the wastewater out into Pegasus Bay, due for completion in late 2008.

‘With the outfall reducing nitrogen inputs by about 90%, we can expect to see a fairly dramatic change in the condition of the estuary’, says NIWA ecologist Dr John Zeldis. John and colleagues are developing a toolkit of biogeochemical and ecological indicators to determine how effective the new outfall will be and estimate how long it will take to remediate the effects of heavy nutrient loads.

The toolkit will be applicable to estuaries around the country.