PROTESTERS have launched legal action against workers involved in the construction of Victoria's controversial north-south pipeline.

About 50 activists gathered on a farm at Glenburn, north-east of Melbourne, to issue Melbourne Water workers with summonses for allegedly trespassing on private property.

The protesters, Plug the Pipe, say workers are not legally allowed on private property to build the pipeline from the Goulburn River to Melbourne and will fight the project in court.

They have employed a barrister who will carry out a citizens' prosecution against six Melbourne Water workers, three of whom were issued with summonses on Tuesday.

They face three charges each, including wilfully entering as a trespasser, neglect or refuse to leave as a trespasser and trespassing likely to cause breach of the peace.

The three are expected to contest the charges in Seymour Magistrates' Court on January 29.

Protesters say this is a landmark development in their fight against the $750 million project, which will pump 75 gigalitres of water each year to Melbourne.

Cattle farmer Don Lawson issued the summonses to workers at the entrance of his property in what will be a test case for the project.

"The Water Act was designed to allow people onto your property if you've got a water meter, if you've got a viaduct, an irrigation licence or whatever - they have every right," Mr Lawson said.

"We believe it has been abused.

"Melbourne Water need to obey the Water Act and treat people with respect and dignity."

Protesters will ask a magistrate to immediately stop the project and throw the pipeline workers off private land while the case is heard.

Barrister Serge Petrovich, who is representing the protesters pro bono, is confident they will win and said more summonses would be issued against water authority workers.

"They're on notice, if we know who they are they will be receiving summonses and we'll be prosecuting them seriously, this is not a joke, we're fair dinkum about this, they're trespassers. We want them off," he said.

"If the government wants to acquire this land it can use the proper legislative processes to do it and stop twisting the Water Act into an intention it was never designed for.

"I don't expect us to be unsuccessful, I think we've got a very reasonable prospect of winning this or we wouldn't have brought it. This is not a stunt - we're fair dinkum about this."

Mr Petrovich said it was not unusual to launch a citizens' prosecution, adding it was much like a citizens' arrest.

Plug the Pipe spokeswoman Jan Beer said the move was not a media stunt.

"We feel they are not allowed on the land and that will be prove in court," Ms Beer said.