The Irish Farmers Association claims homes could be flooded over the coming days unless immediate action is taken.
Acres of land along the River Shannon is saturated after two storms in ten days.
More than 100 millimetres of rain has fallen in several locations in Ireland so far this month.
More heavy rainfall is predicted later this week.
IFA president Tim Cullinan says state agencies have failed to take action on the Shannon, after bad flooding in recent years.