Article courtesy of Jim Chipp | November 6, 2014 | The Dominion Post | Shared as educational material
Although dirty dairying is largely blamed for the poor state of rural rivers, Wellington’s urban waters are far from pristine.
Results of a harbour sediment survey this year found copper, lead, zinc and mercury at some sites around Wellington’s waterfront, as well as oil products above acceptable levels and the banned insecticide DDT throughout the harbour.
A breakdown of Wellington Regional Council enforcement action in the past year reveals that rural and urban areas each contributed to contaminating waterways.
Council environmental enforcement officers issued 18 infringement notices in that period, though three were withdrawn. All but one were urban pollution offences. Almost all were fined $750.
Twenty-three abatement notices were issued, most for discharges to urban streams, and the rest to developers filling in streams without consent. The regional council prosecuted eight for fouling waterways.
The more intensively land is used, the more complex the resulting contaminants are and the greater impact they are likely to have on the environment.
Modern urban living is by its nature an intensive land use.
Wellington Regional Council aquatic ecosystem and quality team leader Juliet Milne said city- dwellers were often unaware of natural waterways because many were underground out of sight and mind.
Consequently, the few remaining, such as Kaiwharawhara Stream, became very popular recreational destinations.
The harbour’s loads of heavy metals, zinc and copper came from a mixture of motor vehicle waste and building materials.
Metals from car tyres and brake linings are deposited as dust on the road. If a street-sweeper does not pick it up before the next rainfall, it washes down the drains into the sea.
Council environmental policy manager Jonathan Streat said that led to residents using stormwater drains to dispose of their waste liquids, unaware they were polluting hidden streams and the harbour.
“The thing that most people do is wash the car right over the stormwater sump,” he said.
It is said commercial cleaners can be seen in the early hours of the morning, pouring their dirty water into gutters or directly into sumps.
What was needed in urban areas was slower flows and areas for soakage.
Council staff have begun addressing stream contamination, engaging with industries where spills can originate to review their practices and distribute educational material.
Although companies were not obliged to co-operate, council environmental protection team leader Susan Smith said all the local businesses participated.
“We do two things,” she said.
“[We provide] a list of requirements of all the permitted activities and rules, and best practice – not part of the rules.”
The council had no powers to enforce that part, but Smith said if businesses implemented best practices and something still went wrong, it would be taken into account when enforcement was considered.
In the next few weeks the day- to-day management of wastewater will move to Wellington Water, formerly known as Capacity, where the man responsible will be recreational water quality manager, Iqbal Idris.
He said the local council’s maintenance routines were reviewed around the harbour areas, where higher concentrations of heavy metals had been found.
Sumps are cleaned at different frequencies throughout Wellington, but more studies were under way since the harbour report.