UPDATED: Diesel has stopped discharging from a stormwater pipe into the Whitianga marina but Waikato Regional Council says the risk has not yet passed.

A clean-up operation began at the marina at about 12pm on Thursday after a quantity of hydrocarbon, believed to be diesel, was seen entering the sea from a stormwater pipe.

Waikato Regional and Thames-Coromandel District council staff are working to clean-up what is believed to be a diesel spill in the Whitianga Marina. Photo: WRC

Regional on-scene commander Dave Lovatt says the council is continuing to closely monitor the situation as it is possible further rain may flush more diesel into the sea.

'Our council's harbourmaster returned to the marina this morning and has removed the sorbent booms, and we believe at this stage the spill has had minimal impact on the environment.

'But while the weather is forecast to improve, there is a possibility of further rain later today and that means any diesel still in the stormwater system could be flushed out.”

Dave says it's still important council identifies the source of the diesel so they can minimise the risk of it flowing into the stormwater system and into the sea.

'So we're renewing our call for Whitianga residents and businesses with diesel storage tanks on their properties to check for possible leaks and to alert us to any issue they might identify.”

Intentionally dumping hydrocarbons like diesel or oil into stormwater systems is an offence under the Resource Management Act, with the cost of the clean-up to be paid by the offender, as well as the risk of a prosecution.

If you have any information on the possible source of the diesel contact the Waikato Regional Council on 0800 800 401.

EARLIER:

Whitianga locals with diesel storage tanks on their properties are being urged to check for possible leaks as The Waikato Regional Council works to contain a spill.

A clean-up operation is underway after a quantity of hydrocarbon, believed to be diesel, was seen entering the sea from a stormwater pipe at the Whitianga marina on Thursday.

The harbourmaster responded by setting up sorbent booms to contain the spill which have remained in place overnight, while additional equipment is being sent to the Coromandel Peninsula to help with the response.

Regional on-scene commander Dave Lovatt says Thursday's wet weather had made the response difficult.

'Heavy rain pushed the diesel through the stormwater system and into the sea, which is making our response more difficult. However, the rain may end up helping to minimise the impact of the diesel on the environment,” Dave says.

'It's unknown at this stage how much diesel has spilled from the stormwater system, but if the discharge continues it could have an impact on the environment.

'Thames-Coromandel District Council staff have been working to trace the source of the spill through the stormwater system, but it's a challenging task.”

Dave is urging people to be diligent about what goes into the stormwater system and, if they have any information on the possible source of the diesel, to contact the regional council.

'It's also really important home and business owners immediately west of the marina check diesel storage tanks they have on their properties for signs of a leak and to let us know straight away if there is an issue.”

Dave warns that intentionally dumping hydrocarbons like diesel or oil into stormwater systems is an offence under the Resource Management Act, with the cost of the clean-up to be paid by the offender, as well as the risk of a prosecution.

People heading to Whitianga for the long weekend should still be able to access their vessels at the marina.

For more information or to report a diesel leak call the Waikato Regional Council on 0800 800 401