Western Victoria MLC Peter Kavanagh said promises the earthmoving machinery would be cleaned before it was moved between properties were being broken.

"Farms can be contaminated with weeds and other contaminants if machinery is not thoroughly washed down between properties. It is extremely important to farmers that soil and weeds on machinery is not taken from one

farm to another," Mr Kavanagh said.

But Central Highlands Water acting chief executive Tony Wright said efforts were being made to reduce the risks of spreading weeds.

"The contractors that are currently constructing the Ballarat Link are required to wash down all machinery when moving between properties," Mr Wright said.

"A wash down bay is set up inside each property and prior to moving on to the next property a disinfectant wash using bore water is carried out for all machinery," he said.

However, the Democratic Labor Party member said machinery used at the White Swan Reservoir project launch in July this year was taken to the actual project start site at Newlyn without being cleaned.

"The potential contamination risks of this failure to clean the machinery was immediately brought to the attention of the pipelaying authority but the seriousness of it all still doesn't seem to be appreciated," Mr Kavanagh said.

"Machinery smothered in mud and caked in soil from distant areas was last week brought onto farming property in Clarke's Hill," Mr Kavanagh said.

"Because there is no independent overseer of the project, farmers have to spend much of their own valuable time watching the pipelayers. This emphasises the need for an independent clerk of works to oversee the project ...something

the farmers have been calling for all year," he said.

But Mr Kavanagh said he wasn't totally opposed to the Goldfields Superpipe.

"Neither I nor the DLP have attempted to stop the pipeline. I have tried however to assist farmers in seeing that the pipe is properly laid," he said.