Drilling for the new Southern Pipeline has been halted after mud used for drilling seeped into the Tauranga Harbour.
Tauranga City Council said in a statement that work on the pipeline harbour crossing was halted about 9am this morning.
Drilling mud has seeped through loose ground and "reached the low tide harbour surface on the Memorial Park side."
The council said a cleanup was underway, with mud being suctioned into a vacuum tanker and taken off site.
They expected to resume work later today but this afternoon project manager Steve Wiggill said drilling was on hold pending assessment by experts.