Farmers have held a protest in Banagher, Co Offaly, over what they claim is the refusal of the National Parks and Wildlife Service (NPWS) to allowing dredging of the River Shannon to go ahead.
Farmers partially blocked the main Shannon navigation route from north to south under the bridge in Banagher.
They said NPWS actions have already led to severe flooding in the area.
The NPWS has denied this.
Tom Turley of the Irish Farmers' Association said farmers would escalate their actions unless a deal drawn up to provide compensation for farmers in special areas of conservation was honoured.
The IFA said it will continue to advise NWPS rangers to stay off famers' lands.