THE Coalition has promised a further $20 million to a voluntary program seeking to fence public waterways in Victoria.

The program now has $45 million in the bank, supporting farmers to fence nearby waterways, on a voluntary basis.

Up to 4500 tonnes of cow bi-product enters Victorian rivers and creeks per day, including the Campaspe, Coliban and Loddon rivers.

Minister for Water Peter Walsh made the announcement of extra funding to the program on Monday.

He said the program also supported revegetation of riverbeds.

"A re-elected Liberal-Nationals Coalition Government will make $45 million available to continue work with Crown frontage licence holders on fencing projects that protect the Crown Land riparian areas beside our waterways and rivers," Mr Walsh said.

"This additional $20 million commitment... will ensure important activities that help care for our waterways and natural environment can continue."

Environment Victoria held staged protests in Bendigo, Ballarat and Geelong in recent weeks, calling for $30 million to fence waterways in Victoria.

Ten protesters dressed as cows and stood alongside a giant inflatable cow at Rosalind Park on Wednesday last week.

During the protest, Environment Victoria healthy rivers campaign manager Juliet Le Feuvre said fencing rivers should be a "straight forward" solution.

"We're not asking farmers to pay. A lot of the land on river banks is public land. There's about 17,000 kilometres of river banks on public land," she said.

The Victorian Farmers Federation had previously voiced concerns over proposals for the mandatory fencing of waterways.

VFF president Peter Tuohey said it was "crucial" that fencing remained voluntary.

"We’re relieved to see the Coalition has not given in to environment groups’ demands to make waterway fencing mandatory," he said.

"Fencing must be a voluntary partnership with catchment management authorities."