AN ENVIRONMENT group is to hire people to gather numbers for a petition supporting government water buy-backs.

Farm groups have attacked it as a "rent-a-crowd" move.

Environment Victoria is looking for people to run community stalls offering information on the Murray-Darling Basin plan.

Applicants need to be "comfortable approaching people on busy shopping strips and will preferably have experience in running stalls or customer service", the ad said.

"You don't need to have a prior knowledge of river issues, although this would be an advantage."

Successful applicants would be required to "proactively" approach people in inner Melbourne "to encourage them to sign a petition". They will be paid $25 an hour.

Victorian Farmers Federation president Andrew Broad accused Environment Victoria of renting a crowd.

"I don't like rent-a-crowds and I don't think it works either," Mr Broad said.

"It's not right. If they've got to pay people, it weakens their cause."

Mr Broad said the people who would fill such positions would probably be well-intentioned but naive.

National Irrigators Council chief executive Tom Chesson said he would volunteer "for free, on the proviso that I can tell the truth".

"It's extraordinary they'll be out there telling people how bad it is when they don't even know much themselves," he said.

"Why don't they go to the communities directly affected and run stalls there - why not go to Deniliquin?"

Mr Chesson said residents in basin communities did not need to be briefed on the Murray-Darling plan.

But Environment Victoria chief executive Kelly O'Shanassy said hiring staff to run stalls was not unusual.

Stalls were often run by EV staff or by unpaid volunteers. But if the organisation had been pushing volunteers too hard, it sometimes had to hire staff.

"It's mainly about information provision - people can sign (a petition) if they want to support more water going back into the Murray River," Ms O'Shanassy said.

"We're looking at places in Melbourne where they're not particularly involved in the Murray-Darling.

"We want them to be more engaged," she said.