The Waikato Regional Council is working to contain a diesel sheen that surfaced at Shortland Wharf in Thames after a 12-metre steel boat sank at the location on Sunday.
A council staff member raised the alarm the following afternoon. Regional On Scene Commander Celeste Davies-Calway described what crews found: "A smell was detected and a light sheen was seen on the water." Oil spill booms have since been laid to soak up the fuel, and council staff are working to determine how far the contamination has spread.

Davies-Calway confirmed that MV Gleaner had shown no sign of leaking since it went down. The vessel submerges completely at high tide and breaks the surface at low tide, and the council is pursuing salvors to raise and remove it from the site.
Shortland Wharf sits among wetlands and coastal habitat. "This is an area of significant conservation value," Davies-Calway said. "We are keen to get out there and identify and protect any areas at risk."
The council had not yet responded to requests for further information at the time of publication.