A structual engineer is due to visit the scene of a collapsed wall beside a Royal Marines base.
Liquid, which some locals fear could have been oil, was seen leaking into the water at Turnchapel, next to the base of 539 Assault Squadron Royal Marines.
The spillage appeared to be coming from underneath a stretch of wall which had collapsed. The MoD said it had been made aware earlier yesterday and contractors had been alerted.
A spokesperson said: “The contractors are awaiting a structural engineer to attend and prepare a report before the way forward can be determined and remedial work.’’
The Environment Agency was unavailable for comment.