Among the rubbish were old lounge suites, chunks of concrete, broken glass, plastic and more.
Newman said he suspected it was dumped in the early hours of Thursday as the tyre tracks looked fresh.
"Who are these people who do this kind of thing? Drive down the beach to dump off their rubbish. Why would you do it?"
The Whanganui District Council's waste adviser, Stuart Hylton, was pleased with the number of people who notified the council about the dumping at South Beach.
He was waiting for statistics for the last two months regarding illegal dumping, but a council report showed an increased number of infringements issued along with customer notifications following its 2020-21 campaign Report Illegal Dumping (RID).
Warning signs, CCTV cameras and fines being pushed to a maximum of $400 were some of the measures put in place.
The campaign is also backed by the Snap Send Solve app that can be downloaded to iPhone and Android phones. It allows people to photograph dumped rubbish and send the picture to the council, with GPS marking its location.
"One of the unintended consequences, if you like, from a concerted illegal dumping campaign is that recidivist dumpers go to greater lengths to dump in out-of-the-way locations," Hylton said.
"Unfortunately illegal dumping is endemic in New Zealand with a percentage of society going to great lengths to avoid disposing of waste at legitimate locations. This is a cost to the ratepayer and our environment."
He said Whanganui had its fair share of illegal dumping, but it was no worse than any other region or district.
"We continue to discourage the practice through the measures contained in our illegal dumping strategy."