Bay of Plenty Regional Council staff are currently responding to a hydraulic oil spill in the Sulphur Point area of Tauranga Harbour.
The spill occurred last night and was caused by a failed hydraulic hose.
Oily water entered the stormwater network, and eventually the harbour, via a stormwater drain, says a council spokesperson.
"Oily water is still being discharged into the harbour but booms have been deployed around the drain to contain the spill.
"Port of Tauranga staff are also responding to the spill and are working to recover oil from the contaminated stormwater in the retention pond via a sucker truck."
AIMS Games Coordinators have been notified.
"An investigation into the cause of the spill is underway but at this stage we are unsure of the size of the spill."