ORBOST dairy farmers have had to dump milk as the flooding Snowy River cut roads and inundated farms.

Murray Goulburn suppliers Joe and Pauline Connelly and their son, Michael, had to dump about 4400 litres of milk valued at about $1760.

Joe said the co-operative would compensate them for the dumped milk, but about 80 per cent of his farm has been flooded for the past two weeks and they had silage reserves for only about four more weeks.

The Connellys dumped 3200 litres of milk on March 4 and another 1200 litres the following weekend as floodwaters blocked access by milk tankers.

The Connellys milk 220 cows on 72ha and with most of the farm under water they had to double the silage ration to 76 round bales a week, increasing grain in the bail from four to 6.5kg per cow per day.

"We don't finish till June, so we can't afford to dry them off now," Joe said.

"Luckily for us a lot of silage has been cut in the area and we might be able to get some at a good price."

Fellow Marlo Rd dairy farmers Vince and Trish Light had up to 80 per cent of their 240ha sharefarm under water.

Their cows dropped production but they didn't have to dump milk.