A special rescue mission on the New South Wales Central Coast has saved hundreds of turtles stranded in two muddy dams.

The alarm was raised on Monday afternoon when the large ponds were drained at a former factory site at Lisarow near Gosford, leaving hundreds of turtles stuck in the mud.

Wildlife A.R.C volunteers have been wading through the mud, up to chest height, to collect the animals.

Spokeswoman, Jessie Grace says about 700 turtles have so far been rescued and will now have to be re-located.

"We've found two species of turtles and they've ranged from little baby ones - 50 cent piece size right up to bread and butter plate size turtles," she said.

"And long neck turtles which we can release locally, and there's long neck turtles in all the creeks around here.

"The Macquarie turtles are a little bit more delicate."

Ms Grace says the Macquarie turtle is a rare species and has indicated the site could be home to a large proportion of the region's population.

Gosford City Council says it is working with the company involved to ensure all processes are followed.

Council's Environmental Officer Shannon McKiernan says it appears the company overseeing the industrial site did not realise the turtles were there when it drained the ponds.

"We've given them a direction not to do any work until such time as we make sure...they can do all the right measures," he said.

Mr McKiernan says the Environmental Protection Agency has also been notified.