After months of finding the yellow bikes abandoned around the city, in the Yarra River and up trees, a string of complaints about dumpings around the Shrine of Remembrance caused the EPA to contact oBike and demand some action.

EPA chief executive Nial Finegan told radio station 3AW that the Singaporean company still had many questions to answer about its management system.

"How are they dealing with complaints? How are they dealing with the abandoned bikes?" he said.

"We've had a response and I'd like to think it's an initial response because it in no way addresses our concerns."

Mr Finegan said the EPA's next step would be to issue the company with a litter abatement notice.

Non-compliance with such notices can result in fines of up to $3171.40.

"If you think oBike are making a dollar or so a trip that could become a very expensive exercise for them," Mr Finegan said.

Mr Finegan also urged the individuals dumping the bikes to stop.

"People who might be frustrated or larking around or might be just idiots - do the right thing," he said.

The bike sharing service has had a bumpy landing in Melbourne since launching in June.

The dockless bikes have been labelled visual pollution and clutter by residents and are considered actual rubbish by the City of Melbourne which has been removing bikes it considers illegally dumped.

In August Lord Mayor Robert Doyle expressed his displeasure with the way the service was operating and said a ban was being considered.

"We are working with oBike but if an agreed solution is not found, this is the track we will have to take," he said.

oBike has been contacted for comment.