Other discharges affect area's water quality

The quality of wastewater discharge into the bay may have significantly improved but many other factors are degrading the water quality of Turanganui a Kiwa’s rivers and sea.

Dr Amber Dunn yesterday (Feb 17) outlined to Gisborne District Council’s Wastewater Management Committee the main aspects of a scoping report for the Turanganui a Kiwa Water Quality Enhancement Project (TAKWQE). The final draft of the report was prepared in conjunction with Ian Ruru and Murray Palmer.

The TAKWQE project, a condition of the wastewater treatment and discharge consent clause 19, aims to improve the water quality and mauri (life force) throughout the region.

Dr Dunn, a coastal science specialist, said wastewater discharge, rivers flowing into the bay and port activities – such as anti-fouling agents, oil and grease – all played a part in degrading the marine environment. River quality was affected by sewer overflows, high sediment loads containing contaminants, land uses and practices and urban stormwater flows.

“Sewer overflows into the rivers are still one of the biggest problems we face, which Council is addressing. The system is old and there is major infiltration into sewer pipes. We are not sure of the impact of industrial stormwater on the Waikanae Stream, for instance.”

The scoping report looked at the four main rivers and smaller streams within the area including feeder streams such as the Te Arai.

She said the scope of issues affecting water quality stretched as far inland as the headwater region of the Waipaoa River. Each river system was hampered by specific localised problems. Waipaoa River’s water quality, for instance, was mostly affected by high sediment loads linked to high erosion rates in the headwater regions.

She recommended an integrated catchment management-type plan taking into account existing conservation projects as the way towards improving water quality and mauri. This would be the vehicle for research, monitoring, planning and specific projects. Community and tangata whenua participation would be vital, she said.

Priorities would be to assess practices along river margins, reduce the use of chemicals on the flats, and revegetate 20 percent of riparian margins.

Committee member Stan Pardoe highlighted the importance of ensuring port activities did not adversely affect the settlement of crayfish puerulus, the largest between the Gisborne district and Castlepoint and a nursery for rock lobster between the Bay of Plenty and Wellington.

“No one can give quantifiable evidence how what happens at the port might affect puerulus. What impact is that having? From an export perspective, this industry is of huge economic benefit to the region.”

Engineering and works manager Peter Higgs assured committee members that the project was not about doing more research that had already been done. It would feed into other ongoing projects, be consistent with other regional planning documents and gather all information happening within and outside of Council.