Hydraulic oil has spilled into the Sulphur Point area of Tauranga Harbour.
Bay of Plenty Regional Council regulatory compliance manager Stephen Mellor said the spill was bought to council's attention at 10.15am today.
"We understand the spill was the result of a failed hydraulic hose for a straddle lift operating at the container terminal," Mellor said.
Six regional council staff are currently responding to the spill.
Oily water entered the stormwater network and eventually the harbour via a stormwater drain.